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AAA


AAA is a classification of computer security protocols encompassing Authentication, Authorization and Accounting. Authentication is the process of confirming that a user requesting services is valid through the use of a password, one-time token or digital certificate. Authorization is allowing a user to access specific types of services including blocking the person from using the service. This also determines the services which the user is granted, and it could be restricted to time, location or multiple logins. Accounting means making a record of the network resources used by those who receive the services for the purposes of planning or billing, for example. Various RFCs define aspects of AAA; RFC 2903 defines generic architecture for use in AAA.

AAA Testing
To test AAA, it is important to consider a wide range of measurements including the maximum number of simultaneous accounting records; maximum session setup rate (Access Requests); maximum accounting rates (Accounting Request - Start and Interim Updates); maximum session termination rate (Accounting Request - Stop); maximum Processing Rates (session processing of multiple activities; e.g., session setup, accounting start, interim updates, and accounting stop). Testing these aspects of AAA will help ensure an overall successful deployment.

More Information on AAA
In the case of equipment vendors, these types of companies must accurately specify the performance characteristics of their equipment under real-world conditions experienced in their customers' networks. Service providers can measure the performance of their AAA services and validate the servers' ability to handle the traffic generated within the network. This allows providers to better comprehend how millions of transactions will affect their servers, and whether their servers will become a bottleneck as next-generation GGSN and PDSNs are deployed to support 3G networks.

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Access Devices


Access devices in the network must be tested thoroughly for bandwidth intensive applications such as IPTV and VoIP. Testing the access devices ensures scalability, reliability and performance. The weakest link in service delivery is between the Digital Subscriber Line Access Multiplexer (DSLAM) and equipment categorized as Customer Premises Equipment (CPE) that entail key systems, PBXs, answering machines and telephone equipment in general.

Access Device Testing
Service providers should simulate large-scale DSL networks to fully stress next-generation access concentrators, servers, DSLAMs and ISAMs. A thorough broadband solution should provide the highest simulated subscriber and node capacity for control and data plane testing of access devices to validate scalability, reliability and performance.

Validation testing should utilize copper-access simulation and impairment generation. Simulators for xDSL and noise generators should allow service providers to verify claims of performance, conformance and interoperability.

Among tests for service providers are IP multicast channel zapping (for video control), local loop emulation integrated with infrastructure and application testing, and emulation of CPE modems to stress test DSLAMs and ESLAMs.

For access device manufacturers, testing information is similar to service providers but should include emulation of CPE modems to stress test DSLAMs, B-RAS, EARS and ESLAMs.

More Information on Access Devices
Services providers and network equipment manufacturers must understand the impact of new access devices on network operations. Various validation tests should be performed, depending on whether the equipment will be used for the purposes of a service provider or equipment manufacturer.

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Analog


In the telecommunications industry, analog means telephone transmission and/or switching that is not digital. The term "analog" comes from Greek which means "similar to." In transmitting telephone signals, the voice, video or image is similar to its original signal on an oscilloscope. For analog transmissions, the two types of signals would look essentially the same except for the frequency level. In the case of analog switches, these switches operate without altering the analog form of the telephone call. Since television signals are analog and computers are digital, any analog signals to be viewed on a computer monitor must be converted into digital form.

Analog Testing Solutions
Service providers and network equipment manufacturers should test by simulating high-density analog subscriber functionality for large-scale PSTN Telephony on a single, integrated platform. The one-box testing procedure means multiple testing devices are eliminated and test costs are reduced.

Testing must occur for the convergence of high-density analog telephony devices to IP telephony according to ITU standards, rather than proprietary technologies that vary from company to company. Users should be able to test on an integrated platform that complies with industry standards.

Testing flexibility should involve the simulation of a wide range of applications associated with switch and network testing. Examples include validating system scalability, identifying capacity limits, measuring call performance, enabling accurate capacity planning and providing end-to-end service assurance.

More Information on Analog
The need for analog testing is still high despite the surge in digital equipment. With the introduction of new technologies such as Voice over IP, Passive Optical Networking, and Terabit to the cabinet and Gigabit to the home, the need for analog testing to ensure convergence and the need to conduct testing at a reasonable price will continue to be prevalent. It is vital to be able to test mature technologies against today's standard set of measurements in a cost-effective manner.

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BGP


The Border Gateway Protocol (BGP) is the core routing protocol of the Internet. The protocol maintains a table of IP networks or "prefixes" that designate which networks are reachable. BGP does not use traditional Interior Gateway Protocol (IGP) metrics, but makes routing decisions based on path, network policies and/or rule sets. BGP supports Classless Inter-Domain Routing (CIDR) and uses route aggregation to decrease the size of the routing tables. All other versions of BGP are considered obsolete. As of January 2006, the current version of BGP, version 4, is codified in RFC 4271.

BGP-4 Testing Solutions
As BGP-4 is the core routing protocol of the Internet, it is extremely important to test different aspects of the protocol. The first test is the basic functionality of BGP. This ensures BGP-4 is able to establish a neighbor relationship, process route updates and forward traffic based upon those advertised routes. This initial test will also be a baseline for each additional test.

Additional tests must follow:
  • Route Table Capacity for determining the capacity for storing and processing BGP routes.
  • Peer Router Capacity to establish the capacity of establishing and maintaining BGP peer sessions.
  • Route Selection with Modified Attributes to validate the BGP router's ability to correctly process BGP attributes.
  • Route Summarization to ensure the BGP router correctly summarizes the BGP routes it obtains.
  • Convergence Times is the final test to determine convergence latency.
Testing these aspects of BGP-4 will help ensure an overall successful deployment.

More Information on BGP-4
BGP-4 facilitates connectivity throughout the labyrinth of the Internet. The protocol provides optimized communications and selects the best path to a destination. BGP-4 is highly responsive to frequent network changes, and its extensions accommodate unconventional routing requirements. Many operational challenges result from the relentless growth of the Internet; the huge number of circuits regularly added and deleted, and the importance of directing traffic in the fastest and most economical route.

That is why companies must test their networks and devices for BGP-4 route convergence - to ensure the continued optimal performance of their portion of the Internet.

Successful testing in advance of any deployment will allow end-users to remain unaware of the quiet but vital role of BGP-4.

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Broadband


Broadband is a medium for transmission that supports a wide range of frequencies. These frequencies range usually from audio on up to video. Broadband carries multiple signals by dividing the total capacity into multiple, independent bandwidth channels. Each channel will then operate only at a specific range of frequencies.

The wider the bandwidth, the more information it is able to carry. In radio, a very narrowband signal is able to carry Morse code; a broader band is needed to carry speech. An even broader band is required to carry music so that none of the high audio frequencies for realistic sound reproduction are lost.

Another example involves data communications and a modem. A modem is able to transmit at 64 kbps over a telephone line, but in using Asymmetric Digital Subscriber Line (ADSL) several megabits can be obtained.

Broadband has several terms related to it. Wideband is a synonym for broadband. Baseband is a single, one-channel band and narrowband is just wide enough to carry a voice. Also, narrowband is sometimes referred to as "not broadband" and could specifically mean rates between 50 cps and 64 Kbps.

Broadband Testing
As broadband is the medium used to transmit data, it falls into the Layer 1 category of the OSI protocol stack. Broadband testing would involve determining if the transmission medium is able to handle the required load.

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Cable Service


Cable offers a system for transmitting television, FM radio programs and broadband services customers. For television, channels are collected at a central site and sent to subscribers in an area by means of a network of optical fiber and/or coaxial cables and broadband amplifiers. For nearly two decades, the most common architecture has been the Hybrid fiber coaxial network.

Traditional cable TV systems worked strictly by way of analog signals (i.e. using standard radio waves) but many modern cable TV systems also employ the use of digital cable technology, which uses compressed digital signals, allowing them to provide many more channels than they could with analog alone. Modern cable TV systems also offer other services such as video on demand, telephony, and high-speed data.

Cable Service Testing Solutions
In general, testing falls into the following categories:
  • Conformance tests ensure that a particular implementation conforms to a certain set of specifications. For example, if a cable modem was designed based on the DOCSIS 1.1 standard, then the object of conformance testing is to verify that it complies with the specification.
  • Interoperability testing ensures that implementations from different vendors will work together. Tests should be designed to verify initialization, negotiation, communications and error recovery.
  • Performance testing measures the performance of an implementation under a variety of operating conditions, including normal, overload and degraded conditions.
  • Direction of Transmission tests are for asymmetrical bandwidth. Performance depends on the direction of transmission. Tests typically have to be run twice - once to determine the downstream performance and a second time to determine the upstream performance.
  • Impaired vs. Unimpaired tests check line attenuation, signal-to-noise or carrier-to-noise ratio as well as crosstalk from adjacent transmitters.
More Information on Cable Service Testing
Cable television was switched on in the late 1940s, and subscription service began about a year later. Nearly 84 percent of American homes have access to cable services, which is also common throughout North America, Europe, Australia and East Asia.

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Carrier Ethernet


Carrier Ethernet is a high speed Ethernet used in Metropolitan Area Networks (MAN). Carrier Ethernet defines native Ethernet access to the Internet and an increasing penetration of wireless networks. Carrier Ethernet is a packet-based alternative to circuit-switched networks that provides standards allowing packet-based traffic to meet all the needs of current users who utilize circuit-switched networks.

Carrier Ethernet Testing
Many types of tests should be run to show conformance. The following is only a sample of all the tests that should be run. A frame delay performance test should be carried out, as the MEF standard states that it should have a 25 msec delay. A frame delay variation performance tests should also be run as required by MEF to have a 10 msec delay. A Quality of Service (QoS) test should be performed as carrier Ethernet has the ability to carry Voice over IP (VoIP) traffic and users are accustomed to a certain standard of call quality.

More Information on Carrier Ethernet
Wireless networks are presenting a challenge to the traditional SONET telephony infrastructure and promise wide area networking scalable beyond 10 Gbps using the ubiquitous Ethernet technology. Metro Ethernet Forum (MEF), a standards organization, has made a commitment to the new standard with the launch of a Carrier Ethernet Certification Program to accelerate the delivery of industry standard products and services.

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CDMA Testing


CDMA
Code Division Multiple Access (CDMA) is a category of protocols for 2G and 3G wireless communications. As a form of multiplexing, which combines multiple signals to create a complex signal, CDMA can optimize use of bandwidth in cellular telephones that operate in the 800 MHz and 1.9 GHz ranges. The original protocol, cdmaOne, was based on ITU IS-95 in the early 1990s and has since evolved.

CDMA uses ADC, or analog-to-digital conversion, that changes signals from analog to digital without changing its basic content. CDMA has increased capacity compared with analog by about 20 times the analog cell service.

ADC is used with spreadCD spectrum cellular service that assigns a code to bits, sends the encoded transmission and reassembles the message to its original content. The spread spectrum service has several advantages. Among them, it limits the effect of interference; transmits the signal only at the rate necessary, thus conserving battery power; and benefits confidentiality or privacy between the transmit source and receipt point.

CDMA Testing Solutions
Testing CDMA should involve the physical layer, protocol layer, deployment and position location as well as core network testing. The tests should be able to be conducted consistently and for reliable and repeatable results. With proper testing, benchmarks can be accurately made and network capacity can be planned. Costly field trials can also be reduced.

CDMA Protocols
While the original protocol, cdmaOne, was first standardized in 1993 and is considered a 2G technology, there are other protocol versions, IS-95A and IS-95B. The IS-95A uses a 1.25-MHz carrier, supports 14.4 Kbps and operates at 800 MHz or 1.9 GHz. The IS-95B supports 115 Kbps and bundles up to eight channels. CDMA2000 was developed as a third-generation version that can support communications ranging in speed from 144 Kbps to 2 Mbps.

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Converged Networks


Converged Networks is the integration of the telephone system with IP-based networks. At one time, it was thought, the deployment, operation and maintenance of a single converged network would be less expensive compared with multiple networks with each offering specific applications. But networks have increased in cost as have devices, even though bandwidth and cabling expenses may have decreased.

While the initial driving force behind the development of the converged network was cost savings, the most current reason is the ability to deploy new applications. This advantage is fundamental to the network in that its devices can access voice and traditional data services at the same time. The same devices can be used to offer multiple services.

The demands are unique and significant for converged networks that must support data and low latency, and packet traffic. Voice and video services can be affected by Quality of Service (QoS) issues such as delay, jitter and dropped packets, making it essential to ensure the network is capable of supplying the needed capacity and performance thresholds. Four main issues are essential to a converged network infrastructure: network planning, network validation, voice quality and VoIP Quality of Service (QoS) security.

Converged Networks Testing
As a converged network will contain both Voice over IP (VoIP) and data networks, testing will require multiple parts. The first step will be to test the data network. The tests that should be run are standard throughput, loss and latency. More advanced tests should also be run, depending on the configuration of your network, such as routing tests, multicast tests and QoS tests. Once the data network has been thoroughly tested, the VoIP part of the network should then be tested. After a complete and thorough testing, a simultaneous test should be run.

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Core


The core or Internet "cloud" comprises various types of networks from numerous service providers and carriers. It contains high-capacity switches and transmission facilities and is sometimes referred to as the center-middle portion of the Internet.

While many kinds of internetwork architectures exist, the generally accepted hierarchy comes in three components: Access, Edge and Core. Access usually connects the customer or customer premise to Edge routers. In the Edge, the carrier may combine a variety of protocols into Core protocols such as IP or ATM.

Core Testing Solutions
Testing should involve real-time traffic generation for creating a wide variety of traffic and packet length distributions. Billions of IP flows should be grouped into user-defined traffic classes for testing Class of Service (CoS) technologies such as DiffServ and Multi-Protocol Label Switching (MPLS).

Test equipment should be available for filtering an auto-identification of incoming packets used for detailed performance and traffic analysis. Quality of Service (QoS) statistics should be made available for throughput, loss, latency and sequence. Data should be provided for packet latency, interarrival time and length distributions.

Functional, conformance and performance testing should be done for a variety of protocols used by the Core.

More Information on Core
Internet Protocol is the most vital protocol for the overall operation of the Internet. IP is a type of delivery system for TCP and UDP, which are transport protocols and responsible for making sure data arrives at its destination host and network.

IP is defined by RFC 791 that was republished as STD 5. RFC 1122 later provided clarification. IP implementations must incorporate both RFC 791 and RFC 1122 for consistency and reliability.

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Cybersecurity


Cybersecurity involves protecting the network or the end systems. Network security involves trying to protect the network from unauthorized access and/or from any malicious traffic. There are different pieces of networking equipment that help to maintain a secure network. A firewall permits or denies a connection to the network. An Intrusion-Protection System (IPS) is another form of access control to protect computer systems from being exploited. An Intrusion-Detection System (IDS) has the ability to detect unwanted traffic and other computer usage that is not viewed by a normal firewall.

Cybersecurity Testing
Depending on the security features implemented in the network, testing the overall Cybersecurity will vary. Testing the ability of your firewall to block traffic on closed ports is a key test to perform. Also, testing the ability of the network to handle a virus outbreak should be performed. If your network uses an IDS or IPS, these should be thoroughly tested to ensure they perform as expected on the network. If your network uses any other Cybersecurity devices, test these as well to determine if they perform to specifications.

More Information on Cybersecurity
With the current growth of the Internet and more viruses spreading, having a secure network is very important. Viruses and hackers are becoming even more intelligent then before; therefore, protecting key systems and information should be taken seriously. A robust and strong Cybersecurity policy will assist in eliminating some of the troubles caused by viruses and hackers.

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Cybersecurity Devices


There are different types of cybersecurity devices that will help to maintain a secure network. The firewall is one of the more important security devices that should be used on a network. It permits or denies any connection to the network, which means the firewall can stop any attack at the entry point to the network. An Intrusion-Protection System (IPS) is another form of access control to help protect computer systems from being exploited. An Intrusion-Detection System (IDS) detects unwanted traffic and other computer usage that cannot be seen by a typical firewall.

Cybersecurity Device Testing
Depending on the security devices used in the network, testing their features and the overall security will vary. Testing the ability of the firewall to block traffic on closed ports is a key test that should be performed. Also, testing the ability of the network to handle a virus outbreak, if one occurs, should be performed too. If the network makes use of and IDS or IPS, these should be thoroughly tested to ensure they perform as configured on the network. If the network makes use of any other security devices, test these as well to determine if they perform to specifications.

More Information on Cybersecurity Devices
With the current growth of the Internet and more viruses unleashed all the time, having a secure network is very important. Viruses and hackers are becoming even more intelligent than before, so protecting key systems and information should be highly important. Using different combinations of security devices can help protect the network.

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DSL


Digital Subscriber Line (DSL) brings high-bandwidth information into homes and businesses over copper phone lines. The speed at which the information arrives and is sent varies, depending on the distance the user is from the telephone company's central office. Connections typically offer 1.544 Mbps to 512 Kbps downstream and approximately 128 Kbps upstream. A DSL line carries data and voice signals. It competes with cable companies and satellite companies for high-bandwidth services provided to customers.

DSL comes in a variety of services. ADSL (Asymmetric Digital Subscriber Line) is set up so that most of the bandwidth is for a downstream that sends data to the user. A small portion of the bandwidth is for upstream use. In contrast, SDSL (Symmetric DSL) carries 1.544 Mbps in the U.S. and Canada, or 2.048 Mbps in Europe, and the data rate is the same for upstream and downstream.

Corporations sometimes use HDSL or High Bit-Rate DSL for wideband digital transmissions within their facilities. This type of line is symmetrical, where the bandwidth for downstream and upstream is equal. HDSL is similar in capacity as a T1 line in North America or an E1 line in Europe, about 2,320 Kbps. Other types of DSL include VDSL (Very High Bit-Rate DSL) for fast connections over short distances and RADSL (Rate Adaptive DSL) where the modem adjusts the connection speed depending on the quality and length of the line.

DSL Testing Solutions
Testing DSL requires several tests and equipment should have remote testing capabilities. Testing should be for wide and narrowband, RFL, TDR, spectral and interference analysis. These tests identify and locate physical-layer interferers such as excessive or insufficient loop length, load coils and varying noise levels. By testing appropriately, the DSL service to a home or office can be pre-qualified for installation or quickly repaired after a trouble diagnosis.

More Information on DSL
The use of DSL has both advantages and disadvantages, depending on location, type of existing wiring and equipment for home or business use.

Advantages include leaving the Internet connection open while being able to use the phone line for voice calls; higher speeds than a regular modem; ability to use existing phone lines; and the company that offers the DSL service provides the modem.

DSL works better when closer to the provider's central office; the connection is usually faster for receiving data than for sending; and, the service is not always available at any location.

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Ethernet/IP


Ethernet is a large group of frame-based networking technologies for local area networks (LANs). Ethernet defines physical-layer wiring and signaling standards along with two types of network access at the Media Access Control (MAC)/Data Link Layer and an addressing format.

Ethernet connects computers with printers, servers, terminals and other network resources at speeds starting at 10 Mbps. Each station is given a single 48-bit MAC address that specifies destination and source of every data packet.

Standardized at IEEE 802.3, the technology gained wide acceptance in the 1990s and continues to be popular today. It has nearly replaced coaxial cable Ethernet, token ring, FDDI and Arcnet. When WiFi was standardized as IEEE 802.11, this wireless LAN technology became popular with Ethernet or began replacing it.

The name Ethernet comes from the medium, luminiferous ether, that was once thought to carry electromagnetic waves through space.

An IP Address (Internet Protocol Address) is a unique number assigned to devices. This number is used to identify and communicate with others on a computer network, which utilizes the Internet Protocol standard. Routers, computers, printers, telephones and other devices must an individual address. IP is defined in RFC 791, RFC 1519 and RFC 1918.

Ethernet/IP Testing
Network equipment manufacturers (NEM), operators and service providers derive different benefits from testing Ethernet. NEMs validate system scalability, identify capacity limits, measure call performance, automate regression testing and test video quality. On the other hand, operators and providers can facilitate vendor selection, identify performance ceiling, enable accurate capacity planning, provide end-to-end service assurance planning, analyze deployments and monitor video quality.

Testing should include objective measurement of voice quality - MOS, PSCM, PSQM+, PESQ, PESQ-LQ, R-Factor and J-MOS - under real-world voice stream load generation. Test methodologies should also support advanced trunking signaling and testing for functional, capacity, performance, interoperability, conformance, robustness, triple play, voice in the presence of video and data, and video quality, among a variety of other tests for modern networks.

More Information on Ethernet/IP
The Ethernet technology has had many names since 1973, when Bob Metcalfe created the specification for Xerox PARC. When Xerox began using it three years later, the company renamed the technology The Xerox Wire. IEEE called the standard 802.3 CSMA/CD which later evolved into Thick Ethernet, Thin Ethernet and Twisted Ethernet. 100Base-T Ethernet became known as Fast Ethernet, and now the technology is at 1 Gbps and beyond.

IP Addresses are able to either be set manually or by Dynamic Host Configuration Protocol (DHCP). DHCP has become widely used, as it sets the IP addresses and keeps track of the ones in use and which are available. Otherwise, the network becomes unstable.

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EV-DO


Code Division Multiple Access (CDMA) mobile phone service providers all over the world have adopted EV-DO (sometimes referred to as Dee-Oh), an abbreviation for 1xEvolution-Data Optimized which is a wireless radio broadband data standard. Standardized by 3GPP2, it is being used in Asia, parts of Europe and Latin America, Israel and Puerto Rico.

The 1xEV-DO Rev B specification includes everything in the earlier Rev A standard and provides the following enhancements: Higher rates per carrier, with speeds of up to 4.9 Mbps on the downlink; bundling multiple channels offering high rates for services such as high-definition video streaming; reduction of latency for games, http, video telephony; hybrid frequency re-use reducing interference; support for asymmetric download/upload services.

1xEV-DO is much faster than other cellular-phone networks and provides mobile devices air interface speeds of up to 2.4576 Mb/s with Rev 0 and up to 3.1 Mb/s with Rev A. However, only terminals with 1xEV-DO chipsets can take advantage of the higher speeds.

EV-DO Testing Solutions
Testing EV-DO should include real-time cdmaOne, CDMA2000 1Xand 1xEV-DO network emulation with inter-generation handoff. In addition, testing would involve multi-sector, multi-BSC emulation and two independent carrier frequencies for true soft and hard handoffs, plus pilot pollution testing; testing of Hybrid Access Terminals (HAT) and dormant handoffs between CDMA2000 1X and 1xEV-DO systems.

Testing also should include overlay services that are supported, including Short Message Service (SMS), Over the Air Provisioning (OTA), data and E-911; embedded Mobile IP and Dynamic Key Mobile IP Update (DMU) support for testing the latest packet data services, along with minimum performance, signaling conformance and Location-Based Services testing.

More Information on EV-DO
Qualcomm in 1999 developed the initial design of 1xEV-DO for IMT-2000 requirements for a greater-than 2-Mbit/s downlink for stationary communications. That standard was called HDR (High Data Rate) and later renamed 1xEV-DO after ratification by the International Telecommunications Union (ITU). It was numerically designated IS-856.

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Fibre Channel


As a gigabit-speed network technology, Fibre Channel is used for storage network. Although its name implies fiber, Fibre Channel signaling runs on twisted-pair copper wire and fiber optic cables. The technology is standardized in the T11 Technical Committee of the InterNational Committee for Information Technology Standards (INCITS). Once used only in supercomputers, Fibre Channel is now the standard connection type for storage area networks (SANs) and for enterprise storage. The Fibre Channel Protocol (FCP) is the interface protocol of Small Computer System Interface (SCSI) on the Fibre Channel.

Three major Fibre Channel technologies are the following: Point-to-Point (FC-P2P), where two devices are connected back to back, and with a simple topology and limited connectivity; Arbitrated Loop (FC-AL), where all devices are in a loop or ring and interruption results when while adding or eliminating a device or when a device fails, but Fiber Channel hubs may connect devices and bypass failed ports; Switched Fabric (FC-SW) when all loops or devices connect to Fibre Channel switches that manage the state of the fabric.

Two of several RFCs upon which Fibre Channel is based are RFC 4369 - Definitions of Managed Objects for Internet Fibre Channel Protocol iFCP; and, RFC 4044 - Fibre Channel Management MIB.

Fibre Channel Testing Solutions
Testing the Fiber Channel protocol involves many steps as it is a very complex protocol. Performance of a device can be greatly affected by design of ports, backplane and buffers, in addition to the way the device handles buffer-to-buffer credits, fabric services and queuing.

Name Server Testing that should be done encompasses sending name server queries, including custom messaging or improperly formatted messages; a switch's ability to handled hundreds of name server queries simultaneously; switch response to the queries; verification the switch under test properly processes name server commands; measuring the results across multiple switches and Interswitch Links (ISLs).

State Change Notification Testing that should be conducted include a switch's ability to handle hundreds of state change notification registrations; checking to ensure a device responds properly to network changes (end node, switch, or ISL failure); simulation of end-node failures to prompt fabric reaction; verification that notifications are sent to the proper end-node; verification that notifications are not sent to unregistered end nodes; checks of the name server to verify that changes are recorded properly; measurement of latency response time following a change.

More Information on Fibre Channel
Fibre Channel offers reliable, cost-effective information storage and delivery at very high speeds. With development started in 1988 and ANSI standard approval in 1994, Fibre Channel is for one and two gigabit communications. The massive amounts of data created today has prompted a wide range of application requirements such as database and file management, transaction processing, data warehousing, imaging, integrated audio/video, networked storage, real-time computing, collaborative projects and CAD/CAE. Fibre Channel is a reliable solution for information storage and retrieval.

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Firewall


A firewall can be either implemented in hardware or in software to prevent and block unwanted traffic from entering in the network. There are different types of firewalls. A packet filter firewall will look at each packet that enters and leaves the network. It either accepts or rejects it, based on preconfigured rules set by the user. An application gateway applies a certain security method to an application. A circuit-level gateway only applies the security method when either a TCP or UDP connection has been established. Once the connection has been established, the packets are no longer checked. A proxy server accepts all messages that either leave or enter the network; this hides what the true network address really is. A firewall usually has two or three of these techniques implemented.

Firewalls Testing
Testing a firewall would require testing its ability to block traffic and act as an application gateway. Also, as traffic will be passing through the device, latency, packet loss and throughput measures should be taken. Depending on your firewall and firewall configuration, other tests might need to be run.

More Information on Firewalls
Firewalls come in many different forms, some of which are small home/small office (SoHo) firewalls. These are usually easily to configure and maintain and normally offer 5 to 8 10/100 ports and will also perform routing if needed. The enterprise-grade firewalls have a much higher port density and offer 10/100/1000 port speed. These firewalls usually require more configuration but offer a greater number of features and/or more robust ones.

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FTTN


Fiber To The Node (FTTN) offers high-speed Internet, voice and other services to homes and apartments. The broadband architecture runs fiber to the node and Very-High-Bit-Rate Digital Subscriber Line (VDSL) over existing telephone copper plant to the residence. Data rate is between 25 Mbit/s and 30 Mbit/s. FTTN costs less to deploy than Fiber to the Premises (FTTP) as the phone wire or coaxial cable is usually already installed. FTTP requires the fiber optic cable to run from the carrier to the residence, adding cost to the installation.

One advantage of using a neighborhood cabinet to terminate the fiber optic cable is that one optoelectric conversion takes place for approximately 100 to 200 users. The cabinet also serves as a multiplexer, allowing the neighborhood users to share the fiber optic cable for access to the carrier network.

FTTN Testing Solutions
Testing is best accomplished at the exact loop the customer is using, providing the service provider visibility to the actual customer experience. Data throughput testing from the Digital Subscriber Line Access Multiplexer (DSLAM) to aggregation and service routers should be accomplished. This allows sectionalization when trouble arises. Testing may include video, Voice over IP (VoIP), IP data, DSL modem emulation, narrowband and other tests.

More Information on FTTN
FTTN is also known as Fiber to the Neighborhood and Fiber to the Cabinet (FTTCab). Regardless of the name, it's a hybrid network architecture involving optical cable from a carrier that terminates in the neighborhood cabinet where the signal is converted to electrical. The connection from the cabinet is then sent through unshielded twisted pair (UTP) for Asymmetric Digital Subscriber Line (ADSL) or via the cable company's coaxial cable.

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Gigabit Ethernet


Gigabit Ethernet (GigE) is a transmission technology based on the Ethernet frame format that transmits Ethernet frames at one billion bits per second (one gigabit). Gigabit Ethernet is a Layer 1 technology that can be run over a copper or fiber line as defined in the IEEE 802.3-2005 standard.

Gigabit Ethernet Testing Solutions
Gigabit Ethernet has become a standard item on Layer 2 and Layer 3 devices. Determining if such devices can process required tasks at Gigabit speed is important. If these devices cannot handle the speed, a slow down in the network will occur. Packets will be lost.

To ensure the device or devices can handle Gigabit speeds, it is possible to generate traffic at Gigabit rate and send this traffic through the device. If the device can handle the traffic rate, no packets should be lost. It is possible to create a more demanding test by using Quality of Service (QoS) traffic streams. In this case, the device will have to look at the QoS field in the header, which will put a greater load on the device. Testing whether such devices can perform at Gigabit speeds will help to ensure a stable and successful network deployment.

More Information on Gigabit Ethernet
Gigabit Ethernet continues to be widely used even though 10 Gigabit Ethernet has recently overtaken it in the core transmission. Gigabit Ethernet has become available on many end stations and is a standard feature on switches and routers. It provides higher transmission speeds between clients and servers. Testing will verify a new piece of Gigabit Ethernet equipment will not cause a slow down in the existing network.

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GPRS


General Packet Radio Service (GPRS) is a mobile data service offered to mobile devices (i.e. cell phones, Blackberry, PDAs) usually described as "2.5G," a technology between 2G and 3G mobile telephony generations. The service provides a moderate speed data transfer using Time Division Multiple Access (TDMA) channels in the Global System for Mobile Communications (GSM). The 3GPP creates the standards that govern GPRS.

GPRS Testing Solutions
As GPRS utilizes an entire mobile device network, the key components of the network should be tested. With a GPRS network, it is likely a user will browse the Internet. A gateway is therefore needed for the GPRS network and the Internet to communicate. GPRS Gateway Support Node (GGSN) acts as a gate between the GPRS wireless data network and other networks, and it should be tested to ensure correct functionality.

Another component of a GPRS network is the Serving GPRS Support Node (SGSN). This device performs mobility and data session management for the GPRS mobile devices. SGSN also performs ciphering, compression of transmitted data and routing of IP packets. Such SGSN node abilities should be tested to determine proper functionality.

Also, the GPRS network should be tested as a single entity. The maximum number of simultaneous activated contexts, rate of context activations and deactivations per second, inter-SGSN handoff rate per second and rates of QoS updates should all be tested on the GPRS network.

More Information on GPRS
Packet-switched data under GPRS is achieved by allocating unused cell bandwidth to transmit data. The available bandwidth for packet-switched data shrinks as dedicated voice or data channels are set up by phones. This leads to a poor bit rate in areas which have many busy cells. The theoretical limit for packet-switched data is 171.2 kbit/s, though a more realistic bit rate is in the range of 30-80 kbit/s.

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GSM


Global System for Mobile Communications (GSM) or formerly Groupe Spécial Mobile is the most popular standard for mobile phones in the world. Over 2 billion people in more than 212 countries and territories use the GSM service. The ubiquity of GSM makes international roaming very common between mobile phone operators, making it easy for mobile phone subscribers to use their own phone in many different parts of the world. GSM is an open standard, which is still undergoing development by the 3rd Generation Partnership Project (3GPP).

GSM Testing Solutions
GSM Testing will also include testing of GPRS. More details about testing GPRS can be found in the GPRS section. GSM should be tested as a complete system, as when mobile phone subscribers use the network the subscriber will use each piece of equipment simultaneously. Testing GSM will require emulation of subscribers and testing on different channels of GSM. Some of the key GSM tests should be the number of subscribers and the ability of the system to handle handoffs.

More Info on GSM
The GSM network is divided into several parts. The first part is the base station subsystem responsible for handling traffic and signaling between a mobile phone and the network switching subsystem. The network and switch subsystem is the next part of the GSM network. It handles the functions of communications between mobile phones and the public switched telephone network (PSTN ). The final part, which is optional, is the GPRS core network that allows packet-based Internet connections.

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HSDPA


High-Speed Downlink Packet Access (HSDPA) is a protocol for mobile telephony that allows higher data transfer speeds on 3G networks based on the Universal Mobile Telecommunications System (UMTS).

HSDPA is an evolution of W-CDMA and offers faster speeds by defining a new W-CDMA channel called High-Speed Downlink Shared Channel (HS-DSCH). This channel operates differently and is used for downlink communications to mobile devices.

The HS-DSCH channel does away with W-CDMA channels' variable spreading factor and fast power control. In their place, it uses Adaptive Modulation and Coding (AMC); fast packet scheduling at the Node B (Base Station); and fast retransmissions from Node B known as HARQ or Hybrid Automatic Repeat Request.

UMTS is occasionally marketed as 3GSM, which shows its 3G nature while also referring to the Global System for Mobile Communications (GSM) technology it was meant to succeed. W-CDMA is the underlying standard based on the 3rd Generation Partnership Project (3GPP) standardization.

HSDPA Testing Solutions
Testing should involve an integrated, automated testing of Release 99 and HSDPA data throughput performance; repeatable and reliable performance testing for exercising the dynamic and adaptive aspects of HSDPA; throughput performance testing from physical layer to true end-to-end IP application; automated testing of data-centric applications to reduce time to market; and, identification of data performance issues that are not identified by standard 3GPP conformance testing.

More Information on HSDPA
The first phase of HSDPA achieves 14.4 Mbps and Phase 2 specified in 3GPP Release 6 calls for data rates up to 28.8 Mbps. The roadmap leads to High Speed Orthogonal Frequency Division Multiplexing Packet Access (HSOPA), also known as LTE (Long Term Evolution), providing data rates up to 100 Mbps for downlink and 50 Mbps for uplink.

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Impairment Emulation


Impairments will affect how well the network operates and the quality of the data transferred. Typical packet impairments include delay, duplication, reordering, fragmentation, loss, errors and jitter. Unfortunately, the typical lab environment does not account for impairments and therefore provides "Best Case" test results.

Impairment Testing
Impairment testing in the laboratory is critical. Service Providers, Chipset Vendors, and Equipment Manufacturers alike need to determine how different types of impairments will affect the performance of their networks, services, equipment, or applications. "Best Case" results simply aren't good enough to the customer or user who wants to know how your product will work in the "real world". Impairment generators and network emulators provide this capability and allow the user to determine, well in advance of actual deployment, just how your product or service will perform in an actual production environment.

Even the best engineered network will contain impairments. Testing with Impairments in advance of actual deployment enables validation, performance and interop testing of systems under real world conditions with precise and reproducible results. With proper testing, the surprises that pop up when deploying into a production network can be mitigated, if not completely eliminated.

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IMS


IP Multimedia Subsystem (IMS) is expected to play a key role in the convergence of telecommunications services and revenue opportunities as new customers are attracted to these services. IMS architecture, based on IP, allows for the delivery of services to subscribers independent of device or network type regardless of location.

IMS can be used to provision true mobility with services that will follow the user from a computer, mobile device or even television set through a single account. IMS is based on open standard IP protocols and numerous RFCs defined by the Internet Engineering Task Force and by many specifications of the 3rd Generation Partnership Project (3GPP).

IMS is a continually evolving series of protocols and interface specifications designed to facilitate standards-based fixed/mobile, voice/data and voice/video convergence. Challenges will arise as dozens of specifications - not all standards-based or expected to become standards anytime soon - may create ambiguity in the development and implementation of communications services. Simply testing the operation of IMS will not be enough. Other tests must be conducted within the initial phase of the implementation and afterward.

IMS Testing
Testing should be conducted to resolve pitfalls in the core network, network access and interworking. For the core, testing may require conformance, load testing, service validation and billing verification and interoperability, among other types of tests. For network access, consider Quality of Service (QoS) and network scalability testing, billing accuracy, WLAN and cellular interworking and others. For interworking, standardized tests should be conducted for voice quality, failover, gateway capacity and others.

More Information on IMS
IMS will eventually become the all-encompassing network for fixed, mobile or wireless. Networks will include General Packet Radio Service (GPRS), Universal Mobile Telecommunication System (UMTS), CDMA2000 and others, particularly Plain Old Telephone Service (POTS) and Global System for Mobile Communications (GSM) supported by using gateways. Operators and service providers will have the flexibility of using a variety of underlying network architectures.

Mobile networking will provide roaming while IMS and Session Initiation Protocol (SIP) will offer user mobility. IP-based services such as Voice over IP (VoIP), Push-to-Talk Cellular, videoconferencing, messaging and other services will become easier to offer to potential customers.

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IP


An IP Address (Internet Protocol Address) is a unique number assigned to a device. This number is used to identify and communicate with other devices on a computer network, which utilizes the Internet Protocol Standard. Any network device including routers, computers, printers and telephones must have its own unique address. An IP address can be thought of as a street address or a phone number, as everyone has a unique street address or phone number. IP is defined in RC 791, RFC 1519 and RFC 1918.

IP Testing Solutions
Testing IP services involves evaluation of the performance of voice, video and/or data over various Internet Protocols. IP can be tested using any protocol or application from Layer 2 through Layer 7 of the OSI 7 Layer model.

More Information on IP
There are actually different IP versions. The most common today is IPv4, with IPv6 gaining in popularity. IPv4 has a limited number of IPs with only about 4.3 billion. IPv6 has 50 octillion addresses, or enough for 57 billion IPs per person. IPv6 was created to help elevate the problem of IPv4 running low on IP addresses. Another version of IP is IPv5, an experimental version never used.

IP Addresses are able to either be set manually or by Dynamic Host Configuration Protocol (DHCP). If more than one of the same IP addresses is present on the same network, systems connected to the Internet will become unstable. This is one reason why DHCP is widely used, as it sets the IP address while keeping track of the ones in use and those which are available.

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IPSec


IP Security (IPSec) is a standardized framework for securing Internet Protocol (IP) communications by using encryption and/or authentication of each IP packet in a data stream. There are currently two ways of implementing IPSec, transport mode and tunnel mode.

In transport mode, only the payload of the IP packet is encrypted. When only the payload is encrypted, it is fully routable as the IP header is sent as plain text. However, it will not be able to cross NAT address space, as this will invalidate its hash value.

In tunnel mode, the entire IP packet is encrypted and must be encapsulated into a new IP packet for routing to work.

IPSec is implemented by a set of cryptographic protocols. These protocols involve the securing of packet flows and Internet key exchange (IKE). Of the former, there are two methods:
  • Authentication Header (AH) provides authentication, payload and IP header integrity.
  • Encapsulating Security Payload (ESP) provides data confidentiality, payload integrity; and with some cryptography algorithm also authentication.
IPSec Testing Solutions
In testing IPSec, it is important to test the cryptographic protocols. This requires testing ESP that is able to use the DES, 3DES, AES, NULL encryption/decryption algorithms and HMAC-MD5, HMAC-SHA, NULL for authentication algorithms. AH supports the HMAC-MD5 and HMAC-SHA authentication algorithm. Depending on the implementation of choice, the needed authentication and/or encryption protocols should be tested to verify IPSec is correctly encrypting/decrypting packets and correctly allowing authentication.

More Information on IPSec
IPsec protocols operate at Layer 3, the Network Layer. Other Internet security protocols such as SSL and TLS operate at Layer 4 and up. This makes IPSec a lot more flexible, as it can be used in protecting both TCP and UDP based protocols. However, it does increase the overall complexity and processing overhead, as it cannot rely on TCP to manage the reliability and fragmentation of packets.

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IPTV/Video


IP Television (IPTV) is a system where digital television service is delivered using the Internet Protocol (IP) and requires a broadband connection for transmission. The playback of IPTV requires either a personal computer or a set-top box connected to a television set. For residential users, IPTV is usually bundled with Video on Demand (VoD), Web access and Voice over IP (VoIP). The commercial terminology for Voice, Video and Internet access is referred to as Triple Play. IPTV provides hundreds of channels to users, and these channels are not limited to the ones available in their area.

IPTV Testing Solutions
IPTV is very demanding on networking equipment because each channel could require up to 8 Mbps. Due to the possibility of this load, a simple capacity test should be run to determine if the network equipment can handle the required load. Also, as IPTV channels are streamed over the Internet using multicast, the equipment should also be tested to determine if multicast support is available and if any restrictions on the number of multicast streams is present. After these basic tests have been performed, it is important to test the channel changing behavior and the video quality.

More Information on IPTV
IPTV covers both live television using multicast as well as stored video (VoD) that uses unicast. Video content is usually in MPEG2 or MPEG4. Live TV uses Internet Group Management Protocol (IGMP) version 2 for connecting to the multicast stream and for changing from one multicast stream to another (changing channels).

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IPv6


IP version 6 (IPv6) is an improvement of IPv4. The main improvement is the increased number of IP addresses available for networked devices, allowing each mobile device to have its own address. While IPv4 supports roughly 4.3 billion addresses (not even enough IP addresses to provide every living person with their own), IPv6 supports 3.4×1038 addresses or 5×1028 (50 octillion) for each of the 6.5 billion people alive today. IPv6 was adopted by the Internet Engineering Task Force in 1994. Even though IPv6 was adopted over 10 years ago, it has had slow acceptance and is finally becoming more widely used. The latest version of IPv6 is defined in RFC 2460.

IPv6 Testing Solutions
Most of the current IPv6 testing tests the ability of IPv6 and IPv4 to communicate. In testing IPv6, it is important to test throughput, latency, packet loss, back-to-back (burst size) and Quality of Service (QoS). Testing these aspects of IPv6 with IPv4 will help determine how adding IPv6 will affect your network.

To reach the IPv6 Internet, a host or network must be able to use the current IPv4 infrastructure to transport IPv6 packets. This is done using a technique called tunneling which encapsulates an IPv6 packet within IPv4. This is another aspect of IPv6 that requires testing to ensure encapsulation is performed correctly.

These are just several tests for IPv6 and many more exist. Depending on the IPv6 deployment, other types of tests should be performed as well.

More Information on IPv6
IPv4 addresses are written using base 10 because each group (4 groups total) will range from 0 - 255, a reasonable number to remember. IPv6 needs to be written in hexadecimal digitals because each of the eight groups could range from 0 to 2^16. Also, to help shorten the overall length of IPv6 address, it is possible to remove any consecutive groups of 0000; this can only be done once per address. If a group starts with a leading 0, it can be omitted as well.

With both IPv4 and IPv6 are currently being used, some networking devices will require a dual stack. A dual stack contains both IPv4 and IPv6 networking stacks. Many of the current IPv6 implementations are dual stack as described in RFC 4213.

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IPv6 Migration


As IPv4 roughly has 4.3 billion addresses and this address space will eventually become exhausted, IPv6 was created. IPv6 supports 3.4×1038 addresses or 5×1028 (50 octillion) for each of the 6.5 billion people alive today. This will solve the problem of exhausting the number of IP address. Not everyone has been willing to migrate over to IPv6 due to the cost and requirements of maintaining both an IPv4 and an IPv6 network. The latest version of IPv6 is defined in RFC 2460.

IPv6 Migration Testing
Most of the current IPv6 testing tests the ability of IPv6 and IPv4s to communicate. In testing IPv6, it is important to test throughput, latency, packet loss, back-to-back (burst size) and Quality of Service (QoS). Testing these aspects of IPv6 with IPv4 will help determine how the addition of IPv6 will affect your network.

To reach the IPv6 Internet, a host or network must be able to use the current IPv4 infrastructure to transport IPv6 packets. This is done using a technique called tunneling which encapsulates an IPv6 packet within IPv4. This is another aspect of IPv6 that requires testing to ensure encapsulation is performed correctly.

These are just several tests for IPv6. Many more exist, and depending on the IPv6 deployment others also should be performed.

More Information on IPv6 Migration
IPv4 addresses are written using base 10 because each group (4 groups total) will range from 0 - 255, a reasonable number to remember. IPv6 needs to be written in hexadecimal digitals since each of the eight groups could range from 0 to 2^16. Also, to help shorten the overall length of the IPv6 address, it is possible to remove any consecutive groups of 0000; this can only be done once per address. If a group starts with a leading 0, it can be omitted as well.

With both IPv4 and IPv6 currently being used, some networking devices will require a dual stack. A dual stack contains both IPv4 and IPv6 networking stacks. Many current IPv6 implementations are dual stack described in RFC 4213.

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IS-IS


The Intermediate System to Intermediate System (IS-IS) protocol is used by network devices (i.e., routers) to determine the best way to forward packets through a packet-based network. IS-IS is an Interior Gateway Protocol (IGP) for use within an administrative domain or network. IS-IS is not meant to be used for routing between networks or domains. As a link-state protocol, IS-IS operates by flooding the topology information throughout the network of routers. Each router then builds a picture of the network's topology. IS-IS was originally described in ISO 10589.

IS-IS Testing Solutions
The first test will validate basic IS-IS functionality. This can serve as a baseline for subsequent IS-IS testing. After verifying basic IS-IS operations and traffic flows, many new variables can be introduced for scalability, performance and negative testing.

The second test should determine the limits of the device's IS-IS route table. This limit will indicate the size of an IS-IS network that different devices are able to support.

The third test determines the quantity of concurrent IS-IS neighbors and adjacencies that the device can support. This limit indicates the maximum quantity of adjacent and neighbor routers with which the device can successfully communicate. Background traffic should be used for a more realistic test.

The fourth and final test should measure the convergence times for new IS-IS route updates and topology changes. This will test the responsiveness to control plane changes (typical occurrences in the real world). During the re-convergence of the device test, the latency, timing, and packet loss associated with this event will be calculated.

More Information on IS-IS
IS-IS testing should focus on the function, performance and scalability aspects of the device. Function testing is the most important aspect of IS-IS testing. There are many roles that an IS-IS router is able to play. Performance testing involves measuring a router's data plane performance while the IS-IS protocol is running. This requires the device to correctly forward packets while supporting the whole IS-IS protocol suite. Route updates and flapping can also seriously impact the device's performance, so these should be tested in the background while continuing to measure the resulting packet throughput, loss, and latency.

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LAN


Local Area Network (LAN) is a computer network that covers a local area such as a home, office or a group of buildings. Current LAN architecture is usually based on switched IEEE 802.3 Ethernet. The speeds at which LANs usually operate are most likely 10, 100, 1000 Mbit/s or Wi-Fi technology.

LAN Testing Solutions
As a LAN is a group of network connected devices, testing a LAN requires that network devices can communicate with one another. In addition, tests at the levels of Layer 2 and Layer 3 should be run since LANs will be routed to other LANs. Testing a Virtual Private Network (VPN) should also be performed if a VPN will actually be used on the LAN.

More Information on LAN
In order to recover from failed links, larger LANs may have a redundant link, and routers or switches that are capable of using the Spanning Tree Protocol (STP). LANs are probably connected to other LANs by routers to create a Wide Area Network (WAN). Most LANs will also have a connection to the Internet, and links to other LANs can be tunneled across using Virtual Private Network (VPN) technologies.

Some of the major LAN technologies are Ethernet, Token Ring and FDDI. Even though the most commonly used LAN technology is Ethernet, the Token Ring and FDDI are still implemented in certain niches.

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Layer 1


Layer 1 is referred to as the physical layer. Layer 1 performs the services required by the data link layer (Layer 2). Layer 1 also refers to network hardware, physical cabling or a wireless connection and deals with electrical specifications, collision control and other low-level functions. As the most basic of the network layers, Layer 1 provides the means of transmitting raw bits.

Layer 1 Testing Solutions
Layer 1 testing involves testing of cabling and hardware. Cable testing determines if the cable is terminated correctly, is not broken and is of high enough quality to pass traffic at the requested speed. Some types of Layer 1 hardware are repeaters, Ethernet hubs, modems and Network Interface Cards (NIC).

More Information on Layer 1
There are several different types of cabling used in Layer 1 such as twisted pair cables, coaxial cables and fiber optic cables. The physical layer also defines how each bit will be represented as a voltage, current, phase or frequency. The basic schemes used are Return to Zero (RZ), Non Return to Zero (NRZ) and Manchester Encoding.

The physical layer is the only layer in which data is physically moved across the network interface. The rest of the layers perform useful tasks to create data to be sent, and this data is then transmitted down the protocol stack to the physical layer, where it is actually sent out over the network.

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Layer 2-3


Layer 2 referred to as the Data Link Layer deals with the transmission of data between adjacent networks or between nodes on the same Local Area Network (LAN). Layer 2 provides the functional and procedural means to transfer data between network entities and might also be able to detect and correct errors that occurred in Layer 1 (Physical Layer). Examples of data link protocols are Ethernet and PPP.

Layer 3 also known as the Network Layer translates logical addresses and names into physical addresses. Layer 3 determines the route from the source to the destination system and manages problems involved with traffic such as switching, router and congestion control. This layer is responsible for end to end packet delivery while the Data Link Layer (Layer 2) is responsible for hop to hop packet delivery.

Layer 2 and Layer 3 Testing Solutions
To test Layer 2, it is possible to generate traffic at line rate and send the traffic through a Layer 2 device. The device should able to handle the traffic rate with no (or minimal) packet loss. Another Layer 2 test, a bit more demanding, is a Quality of Service test (QoS). The device will have to inspect the QoS field in the header; in doing so, this will put a greater load on the device.

Layer 3 testing is possible by testing any of the routing protocols such as OSPF, RIP, IS-IS and BGP. The device would be configured to support the routing protocol and routes would be injected into the device. Traffic could then be sent from one host to another. Each routing protocol has its own set of features that could be tested to determine overall Layer 3 functionality.

More Information on Layer 2 and Layer 3
The Data Link Layer (Layer 2) is often conceptually divided into two sublayers: the Logical Link Control (LLC) and Media Access Control (MAC). LLC refers to the functions required for establishment and control of the logical links between hosts. MAC refers to the procedures used by devices to control access to the network medium. Since most networks share a medium, it is necessary to have rules for managing the medium to avoid conflicts.

The Network Layer (Layer 3) is the lowest layer, concerned with getting data from one computer to another even if the other computer is on a remote network. Layer 3 is also involved in the encapsulation of messages received from higher layers. These messages are placed into datagrams, also known as packets, with a Network Layer header. Some technologies have a limit on the length of packets they can handle or fragmentation will result. Layer 3 handles the fragmentation and reassembling of these packets.

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LDP


Label Distribution Protocol (LDP) is used between two label-switched routers (LSR) to exchange label mapping information. The two LSRs are called LDP peers and the information is exchanged in a bi-directional method. LDP builds and maintains the LSR databases that forward traffic through a Multi-Protocol Label Switched (MPLS) network. LDP employs a discovery method to locate and enable LSR peers. It has four types of messages: discovery, adjacency, label advertisement, notification. LDP is run over TCP, besides the discovery message which is run over UDP.

LDP Testing Solutions
As LDP is part of MPLS, LDP can be tested by running different MPLS tests. To test LDP unaccompanied, it would be recommended to perform a forwarding performance test for the transit LSR. Also, a forwarding performance test for the ingress label edge router and a forwarding performance test for the egress label edge router should be conducted.

More Information on LDP
LDP was designed to be easily extensible, using a specified message that are collections of TLV (type, length, value) encoded objects. TLV provides an encoding means that each object will contain a type field to say what type of object it is, a length field to say how long it is, and a value field. The value field depends on the type field. New capabilities are easily added with a new type definition.

Popular Layer 7 protocols include HTTP, FTP, SMTP, DHCP, NFS, Telnet, SNMP, POP3, NNTP, and IRC. Also, not all users of the Application Layer are applications. The operating system uses services directly at the Application Layer.

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Load Balancers


A load balancer distributes the required load between different servers and maintains optimal performance of the requested service. A load balancer also maintains the needed service even if one server goes down. If a server fails, the balancer can redirect traffic to a back-up server if one is configured.

A load balancer can be considered a Layer 4-7 router, as it will direct traffic to the correct server based on different reported values, such as processor utilization, the current number of connections to the server and overall performance.

Load Balancer Testing
Since the load balancer forwards traffic throughput, loss and latency tests should be performed to ensure the balancer will not hinder the network severely. A basic test that can be run is characterizing what the balancer's operating limits. Next, a stress test will measure the operating limits with connection-based load balancing. Finally, measure the operating limits with a request-based load balancing test.

More Information on Load Balancers
A load balancer makes sure that no single server will be overwhelmed by the number of requests it needs to handle. Also, the use of a load balancer can help in the event of a denial-of-service attack (DoS), as the attack will be spread out over a greater number of servers than only one.

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MAN/Metro


A metropolitan area network (MAN) is a moderate to high-speed network linking several locations within a service area, campus or city. The network can extend 30 miles and operate at speeds approaching 200 Mbit/s. MAN is defined by the IEEE 802-2001 standard.

One company or organization may own or operate such a network that allows an internetworking means for a number of smaller local area networks. Employees and authorized persons can use the MAN to conduct business more efficiently.

Some computer networks comprising a MAN use Frame Relay, Asynchronous Transfer Mode (ATM) and other technologies, but many of these older technologies are being replaced with more modern networks. In their place, Metro Ethernet is being used more readily. At one time, MANs were mainly connected by optical fiber, but they are now increasingly linked by microwave, radio or infrared laser connections.

MAN Testing Solutions
Ethernet services are extending out from LAN to IP services for LAN, MAN and Access deployments creating a carrier-class Ethernet service. A major challenge lies in validating and deploying devices that encompass these areas while handling a massive increase in port density and speeds, as well as new services such as IPTV and Ethernet.

More Information on MAN
The MAN standard for data communication is Distributed Queue Dual Bus (DQDB) specified in the IEEE 802.6 standard. Networks using DQDB can operate at speeds between 34 Mbit/s and 155 Mbit/s.

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MLD


Multicast Listener Discovery (MLD) comprises three Internet Control Message Protocols (ICMP) and manages subnet multicast membership for IPv6, while replacing the Internet Group Management Protocol (IGMP) for IPv4. MLD enables IPv6 routers to discover multicast listeners on directly attached links and then determines which multicast addresses are of interest to the nodes.

MLD was originally defined in RFC 2710, and later updated in RFC 3810 as MLDv2. MLDv2 allows a node to report its interest for listening to packets with a particular multicast address only from specific source addresses, or from all sources except for specific source addresses.

MLD Testing Solutions
Among other tests, conformance tests should be conducted on reserved fields handling, join/leave, multicast group solicitation, transition procedures and other operations. The router should be tested for its ability to conform to RFC 2711 - IPv6 Router Alert Option and RFC 2464 - Transmission of IPv6 Packets over Ethernet (POE).

In addition, tests should evaluate switches and routers under typical or extreme multicast traffic load conditions for minutes, hours and days. Also, the key functional parameters of routers and switches should be tested when combining multicast traffic with Quality of Service (QoS), routing and data forwarding. The ability of switches and routers also should be verified for managing users joining and leaving multicast groups over extended periods.

More Information on MLD
Multicast most often refers to IP Multicast, allowing routers to form spanning tree distribution paths. Meanwhile, ICMP for IPv6 is a vital component of IPv6 architecture and must be completely supported by all IPv6 implementations.

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Mobile Devices


A mobile device is a small device that is able to be handheld and usually has a small display screen and a miniaturized keyboard. There are three categories of mobile devices. The first category is "Limited Data Mobile Device." These have a smaller, text-based screen and usually have limited Short Message Service (SMS) and WAP access. Examples of this category are cellular phones.

The second category is "Basic Data Mobile Devices," with a larger screen and navigation by a thumb-wheel or cursor. They offer access to e-mail, an address book, SMS and contain a very simple Web browser. Examples of this category are smartphones.

The third and final category is "Enhanced Data Mobile Devices." These devices have some of the largest screens and offer the same features as the Basic Data Mobile Devices, with other native applications and custom corporate applications. Examples of these devices include those that run on the Windows Mobile platform.

Mobile Device Testing
Testing a mobile device would involve testing the network the device will be using. Depending on the network, different tests will have to be performed.

More Information on Mobile Devices
Most mobile devices are able to send and receive faxes by having the fax sent to an e-mail address. To have this done, an Internet faxing service needs to be used. Also, it is possible to print documents by having them sent to a nearby fax machine.

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Mobile IP


Mobile IP is a standard communications protocol that allows a mobile device to move from one network to another while still maintaining a permanent IP address. Mobile IP is described in RFC 3344.

Mobile IP Testing Solutions
Testing Mobile IP involves several different tests. With Mobile IP, it is crucial to ensure the mobile device is able to receive and process the care-of IP address. Once it has been successfully determined the mobile devices can receive and process the care-of IP address, testing the tunneling ability of the home agent is next. Another test has to be conducted as well, which is the ability of the foreign agent to process packets correctly.

More Information on Mobile IP
Mobile IP is most often found in wireless WAN environments where users carry mobile devices, whose IP addresses change across multiple LANs. In some situations such as VPN and VoIP, a change in an IP address could cause problems.

Mobile IP works as follows: The mobile node has two addresses. The first address is a permanent home address and the second one is a care-of address. The care-of address is associated with the network the mobile node is visiting.

Mobile IP has two kinds of entities: A home agent stores information about mobile nodes, whose permanent address is in the home agent's network; and, a foreign agent storing information about mobile nodes visiting its network. These agents also advertise care-of addresses used by Mobile IP.

A node that wants to communicate with the mobile node would use the home address of the mobile node to send packets. These packets are intercepted by the home agent, which uses a table. The home agent will tunnel the packets to the mobile nodes care-of address with a new IP header. The packets are decapsulated at the end of the tunnel to remove the added IP header and then delivered to the mobile node.

When mobile nodes act as senders, they simply send packets to the other communicating node through the foreign agent.

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MPLS


Multiprotocol Label Switching (MPLS) is a data-carrying mechanism which emulates some properties of a circuit-switched network over a packet-switched network. MPLS operates at an OSI Model layer considered between Layer 2 and Layer 3 . MPLS is often referred to as a "Layer 2.5" protocol. It was designed to provide a unified data-carrying service for both circuit-based clients and packet-switching clients which provide a datagram service model. MPLS carries many types of traffic including IP packets, Asynchronous Transfer Mode (ATM), Synchronous Optical Networking (SONET) and Ethernet frames. MPLS is currently standardized in RFC 3031.

MPLS Testing Solutions
MPLS requires the testing of both Label Distribution Protocol (LDP) and Resource Reservation Protocol - Traffic Engineering (RSVP-TE). LDP is a protocol with two Label-Switched Routers (LSR) exchanging label mapping information. The two LSRs are called LDP peers and the exchange of information is bi-directional that is used to build and maintain LSR databases. LSR databases forward traffic through an MPLS network. RSVP is a protocol that supports the reservation of resources across an IP network. RSVP-TE is described in RFC 3209, and it allows the establishment of LSPs. RSVP-TE takes into consideration network constraint parameters such as bandwidth and hops.

The forwarding performance of LDP for the Transit LSR, Ingress Label Edge Router (LER), Egress LER all need to be tested. As for RSVP-TE an establishment stress test and performance of the transit LSR, Ingress LER and Egress LER also need to be tested. Other tests exist that test the overall scalability of MPLS, including BGP/MPLS VPN and Layer 2 frames over a MPLS network.

More Information on MPLS
MPLS works by prepending packets with a MPLS header. This header contains one or more labels and is called a label stack. A label stack contains four fields. The first field is a 20-bit label value, and the second is a 3-bit Quality of Service (QoS) priority field. The third field is a 1-bit bottom of stack flag. If set, it signifies the current label is the last in the stack. The fourth and final field is an 8-bit time to live (TTL).

These MPLS labeled packets are forwarded/switched after a Label Lookup/Switching instead of a lookup in an IP table. The exit points of an MPLS network are called Label Edge Routers (LER). Routers performing routing, based only on Label Switching, are called Label Switched Routers (LSR).

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Noise


Electrical signals affecting telephone lines and originating from the circuit or through natural occurrences define noise. Such introduced electrical signals often degrade line performance. Noise, which can occur in digital or analog systems, can be considered meaningless data or data that has no signal and is a byproduct of variations in the current or voltage or other factors.

Testing with Noise
Testing should involve generating impairments for narrow and broadband noise, crosstalk and transient impairments while testing ADSL, SDSL, HDSL or other types of transmission systems. Some testers offer saved files of noise combinations that can be easily retrieved, used and re-used as required to ensure noise can be tested and dealt with before network deployment or in the lab. Noise testing should follow a variety of standards defined by ITU-T, ETSI and T1E1.4 Subcommittee.

More Information on Noise
Noise is often more significant in wireless system than wired systems and engineers are always working to find better ways to handle the problem. Traditional methods have called for minimizing signal bandwidth but this procedure limits data speed. Fiber optics are less susceptible to noise but more expensive to install and use. Noise is more common at lower frequencies, particularly noise caused by the atmosphere or electronics. Outside noise levels are directly proportional to wavelength and inversely proportional to frequency.

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Optical Fiber


Optical fiber is used to transmit information from one point to another point using electromagnetic carrier waves modulated to carry data. The first fiber-optic systems were developed in the 1980s, and they have come to play a major role in advancing the telecommunications industry and the many services being developed.

Fiber-optic communication systems use a transmitter to convert electrical signals to optical signals. Once the signal is sent through the fiber, an optical receiver on the other end recovers the signal by turning it back into an electrical signal. Information from computers, telephone systems and cable television firms are typically sent through fiber-optic systems.

One of the most prevalent systems is Synchronous Optical Network Transport (SONET), which is a means for transporting many digital signals with different capacities over fiber.

Optical Testing
Testing may include evaluating in the lab the impact of optical channel physical impairments (e.g. splices), attenuation, and dispersion effects on optical networks utilizing OC-48 and OC-192 transmission rates, across different combinations of wavelengths, fibers and network configurations. Bit Error Rate testing may conducted to check for errors, and other tests can be done for manufacturing tests and quality control of optical systems, equipment calibration and performance evaluations.

More Information on Optical
Attenuation and interference is less with optical fiber, which has a large advantage over copper wire in terms of long distances and high-demand scenarios. While this advantage exists, it is more difficult to lay such systems in cities due to infrastructure requirements. For this reason, fiber-optic systems have been mainly used for lengthy distances. However, new housing developments are increasingly using fiber to the home systems that support high-bandwidth and high-speed transmission.

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OSPF


Open Shortest Path First (OSPF) is a link-state, hierarchical interior gateway protocol (IGP) for networking. OSPF is based off Dijkstra's algorithm to calculate the shortest path trees. It uses a cost as the routing metric. A link-state database is constructed of the network topology which is identical on each and every router in the area. OSPF is documented in RFC 2740 for OSPFv2 and RFC 2740 for OSPFv3.

OSPF Testing
In testing OSPF, the basic overall functionality should be tested first. This will verify the networking and device are correctly configured. Once the overall functionality has been tested and verified, more specific OSPF tests can be run. An OSPF route table capacity test will determine the device's ability and capacity for storing and processing OSPF routes. The next test is an OSPF neighbor capacity to determine the capacity for establishing and maintaining OSPF adjacencies and neighbors. An OSPF capacity test will ascertain the capacity for establishing and maintaining OSPF adjacencies and neighbors across multiple areas. Finally, an OSPF convergence time test will determine the device's OSPF convergence latency.

More Information on OSFP
OSPF is probably the most widely used IGP in large networks. OSPF operates securely, using MD5 to authenticate peers before forming the needed adjacencies and accepting link-state advertisements (LSA). OSPF is a natural successor to Routing Information Protocol (RIP). OSPF from the start was a classless routing protocol. OSPF is also able to support IPv6 with the current version, OSPFv3. Also, Mulitcast Open Shortest Path First (MOSPF) exists, which uses multicast extensions in OSPF.

OSPF uses a backbone area, also known as area zero. The backbone area forms the core of an OSPF network. All other areas are connected to the backbone, and all other inter-area routing happens by a router connected to the backbone area. The backbone area is responsible for distributing all the routing information between non-backbone areas.

A stub area is an area which does not receive external routes. External routes are routes that were distributed in OSPF from another routing protocol. A stub area usually depends on a default route to send traffic to routes outside the present domain. Other types of stub areas exist too, such as the totally stubby area and not-so-stubby area.

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Packet Core


The IP-based Mobile Packet Core Network is an integral part of delivering new IMS-based multimedia services to mobile users. The network will carry voice, video, and data and deliver it to the user. The performance, scalability, and Quality of Service (QoS) the Mobile Packet Core delivers has substantial impact on end customers' perceived quality in a carrier network.

Proper testing must be performed to quantify how network elements will perform not only in isolation but as part of a complete system. Testing capabilities should include 3GPP or 3GPP2 standards in addition to emulating and testing every network element in GPRS/UMTS and CDMA2000 Mobile Packet Core.

Packet Core Testing
Tests should include Quality of Service (QoS) and network scalability testing.

The mobile packet core network is critical for delivering application traffic to the user. If not properly tested, perceived quality of the entire network can be jeopardized.

Many potential pitfalls exist, including low throughput of data, poor QoS for delay or loss sensitive applications, dropped calls during handovers, and call establishment failures due to capacity overloads. Proper testing consists of the emulation and testing of every network element in the packet core in isolation or as a system. It must be possible to emulate millions of IMS enabled mobile nodes with real-world traffic models.

More Information on Packet Core
Real-world traffic models with a wide range of application traffic (SIP, HTTP, RTP, Mail) should be simulated in a lab environment, with a very small foot print. This saves the cost, complexity and lab space of trying to cobble multiple devices together. Such testing is critical to customers wanting to accelerate time to market for their new products and services.

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PIM


Protocol-Independent Multicast (PIM) is a group of multicast routing protocols. PIM is able to provide one-to-many and many-to-many distribution of data over the Internet. The "protocol-independent" part refers to how PIM does not include its own topology discovery mechanism, but uses routing information supplied by other routing protocols such as Border Gateway Protocol (BGP).

PIM Testing
As PIM Sparse Mode (PIM-SM) requires the use of Rendezvous Points (RP), it is important to test the operations of the RP, validating its functionality, processing of PIM "join" requests and traffic forwarding. Validating the device's ability to ensure it will not forward multicast traffic back from its sender is important in avoiding loops. A reverse path forward check test will validate the device's ability by generating a traffic stream that violates the condition. The stream should not then be forwarded to the multicast group.

More Information on PIM
There are four variants of PIM. The first one is PIM-SM that builds unidirectional shared trees rooted at a RP per group and optionally creates shortest-path trees per source. PIM-SM generally scales fairly well for wide-area usage. The second one is PIM Dense Mode (PIM-DM). PIM-DM implicitly builds shortest-path trees by flooding multicast traffic domain wide, and then pruning back branches of the tree where no receivers are present. PIM-DM generally does not scale nicely. The third one is, Bidirectional PIM which explicitly builds shared bi-directional trees. It never will build a shortest path tree, so it may possibly have longer end-to-end delays then PIM-SM. Bidirectional PIM scales nicely because it does not need any source-specific state. The fourth and final one is PIM Source Specific Multicast (PIM-SSM). PIM-SSM builds trees that are root in just a single source. This offers a more secure and scalable model for limited amount of applications. Of the four variants PIM-SM is more widely and commonly used. The RFC for PIM-SM is RFC 2362.

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POE


Power over Ethernet (PoE) is a technology for transmitting electrical power, along with data, to remote devices over standard twisted-pair cable in an Ethernet network. PoE is very useful for powering Voice over IP (VoIP) phones, wireless access points and webcams.

POE Testing
With PoE, the Power Signaling Equipment (PSE) is the main piece of equipment that should be tested. Several tests should be run to determine the overall functionality of the PSE, including a load and a compliance test. These tests will help determine the amount of true power output and whether the PoE system was correctly implemented. Also, a signal detection test should be run so that the PSE supplies power only to those devices which require it. A variety of tests can be run depending on the configuration of PoE in the network.

More Information on POE
As two types of standards currently exist for twisted-pair cables, TIA-568A and TIA-568B), two modes are available for PoE. Mode A, pins 1-2, form one side of the 48-volt DC supply. Pins 3-6 provide 48-Volt return for the TIA-568A cable standard.

In mode B, pins 4-5 form one side of the DC supply and pins 7-8 provide the return. These pins are used for they are considered spare pairs in 10Base-T and 100Base-TX. Mode B, therefore, requires a 4-pair cable. The PSE determines whether mode A or B will be used. The PSE can implement mode A or B or both, but it cannot supply power in both modes at the same time.

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PoS/SDH


As a communications protocol, Packet over SONET/SDH is for transmitting packets in the form of Point to Point Protocol (PPP) over Synchronous Digital Hierarchy (SDH) or Synchronous Optical Networks (SONET). On the Internet, a huge amount of Wide Area Network (WAN) traffic is carried on Packet over SONET links.

PoS is defined by RFC 2615 as PPP over SONET/SDH. PPP is a standard method for point-to-point communication. PoS is a link layer used by the IEEE 802.17 Resilient Packet Ring (RPR) standard.

SDH and SONET encapsulate previous digital transmission standards or can be used to support Asynchronous Transfer Mode (ATM) or PoS networking. While SONET is widely used in the United States and Canada, SDH has been implemented in many other parts of the world. SDH is growing in usage. While SONET's signal is 51.840 Mbit/s (STS-1, Synchronous Transport Signal One), SDH's basic unit (STM-1, Synchronous Transport Module-Level 1) operates at 155.52 Mbit/s.

PoS Testing
Testing should involve measurement of all key metrics, including true load capacity, latency and IP frame sequencing using industry-standard tests. Key performance parameters of PoS routers should be evaluated under typical or extreme traffic load conditions. Also, PoS routers should be qualified during development in addition to quality assurance and final regression testing. This improves time to market and reduces failure risk.

More Information on PoS
PPP was designed as a standard method for communicating over point-to-point links. SONET/SDH utilizes point-to-point circuits. Therefore, PPP is well suited for use over these links. Class of Service (CoS) is assigned to traffic on the ring.




PPP


Point-to-Point Protocol (PPP) is commonly used to establish a direct connection between two nodes. It can connect computers using a serial cable; phone line, trunk line, cellular telephone or fiber optic links. Most Internet Service Providers (ISP) use PPP for customers who use dial-up to access the Internet. PPP is described in RFC 1661.

PPP Testing
Testing PPP involves several different tests. Testing would require PPP over Ethernet (PPPoE), PPP over AAL5 (PPPoA) and PPP over Ethernet over AAL5 (PPPoEoA). Frame Check Sequence (FCS) and Link Control Protocol (LCP) would also need to have different tests to determine their correct functionality.

More Information on PPP
PPP is commonly referred to as a Layer 2 protocol and designed to work with many of the Layer 3 protocols. PPP includes many features seen only in various proprietary data-link protocols up to the time of its implementation. PPP uses a FCS field to determine whether an individual frame has an error and then monitors the frequency with which frames are received in error. An integral part of PPP is the LCP that provides automatic configuration of the interfaces at each end. Another key feature is the ability of PPP to detect looped links.

Many RFCs have been published about PPP since July 1990, including various authentication, encryption and compression methods.




PSTN


Public Switched Telephone Network (PSTN) is the combination of the world's public circuit-switched telephone networks. Originally, the PSTN was a fixed-line analog telephone system, but now it is almost entirely digital and includes mobile as well as fixed telephones. The PSTN is governed largely by technical standards created by the ITU-T and uses E.163/E.164 addresses (also known as telephone numbers) for addressing.

PSTN Testing
Service providers should test by simulating a high density number of call setups and tear downs. The quality of the call should be measured to determine if the call is actually clear enough for the other user to understand.

More Information on PSTN
PSTN is the earliest example of traffic engineering to deliver Quality of Service (QoS) guarantees. The oldest parts of the telephone network still use analog technology for anything other than the last mile loop to the end user. In recent years, digital services have been increasingly rolled out to end users.

Some people believe that the future of PSTN is to be an application of the Internet, but the Internet is not yet able to handle this demand yet. The QoS guarantee is one such item that needs more improvement in Voice over IP (VoIP). A large number of private telephone networks which are not linked to the PSTN exist. These private networks are run either by large companies or for military purposes.




RIP


The Routing Information Protocol (RIP) is one of the most commonly used Interior Gateway Protocols (IGP) on internal networks. RIP helps routers dynamically adapt to changes of network connections by communicating information about which networks the router can reach and how far away those networks are (or how many hops). RIPv2 is defined in RFC 2453 and RIPng (IPv6 support) is defined in RFC 2080.

RIP Testing
Network equipment manufacturers (NEM) should perform a through and detailed testing of the implemented RIP protocol. This would involve testing the maximum number of routes the route table is able to hold and process. Also, important are testing RIP's configurable update interval and the correct processing of the updated route information. The MD5 or simple authentication should also be tested to verify correct functionality.

More Information on RIP
Although RIP is still actively used, it is generally considered to have been made obsolete by routing protocols such as Open Shortest Path First (OSPF) and Intermediate-System to Intermediate-System (IS-IS). As mentioned, RIP uses the number of hops to determine the distance of other networks. The maximum number of hops allowed by RIP is 15. Every 30 seconds, each RIP router will transmit full updates and this will cause a lot of extra traffic on the network that reduces the overall bandwidth available.

In designing a new network, RIP would probably not be the first choice of a routing protocol as convergence times and scalability are poor compared to OSPF and IS-IS, and the hop limit severely limits network size. RIP, however, is easier to configure than the others.




Routers


A router is a device connected to two or more networks, and it determines the best way to transmit data to the requested network. To determine the destination network, the router will inspect the header file and then do a look up in a table to determine the best possible way to forward the packet. Routers will communicate with one another to send information that supports determination of the best route. As routing takes place in Layer 3, a router is considered a Layer 3 device.

Router Testing
A router depends on a routing protocol to determine how to transmit the data. There are several commonly used routing protocols. Depending on the network configuration, the intended routing protocol should be tested. The routing protocol could be Border Gateway Protocol (BGP), Open Shortest Path First (OSPF), Intermediate System to Intermediate System (IS-IS) or Routing Information Protocol (RIP).

If multicast traffic is expected to be transmitted through the network, IGMP and PIM should also be tested. PIM needs to be tested since multicast traffic will also need to be routed to the correct destination network. Other technologies should also be tested depending on the network. Two such technologies are Virtual Private LAN Service (VPLS) and High Availability Routing (HAR).

More Information on Routers
There are different classes of routers. A home network and small office will not require the same throughput and port density that large, corporate networks would need. This is why many router vendors make different classes of routers available. Depending on the class of router, a different set of features will be included.




RPR


The Resilient Packet Ring (RPR) standard, also known as IEEE 802.17, optimizes the transport of data over fiber rings and makes SONET/SDH networks using a packet-based transmission more resilient. As a result, services based on Ethernet and IP become more efficient. SONET/SDH stands for Synchronous Optical Network/Synchronous Digital Hierarchy.

RPR uses dual, counter-rotating rings known as ringlets that are set up by forming RPR stations at nodes where traffic drops. The Media Access Control (MAC) protocol is used to direct traffic moving in both directions around the ringlet. Nodes negotiate bandwidth using algorithms. Through the process of steering, if a node or span becomes inoperative, the nodes in the system are notified to reroute traffic. Using the wrapping process, traffic loops back to the previous node prior to the break in operation and is then routed to the final destination.

RPR Testing
Several tests are required to properly test RPR, including the following: The basic test establishes the emulated ring and allows traffic to be generated and analyzed as it transits the DUT (Device Under Test) or ingress/egresses the ring through the DUT. A fault protection test investigates the ability of the DUT to properly react to an edge create event and also tests recovery time. Any lost packets should be recorded and reported. Then comes the congestion test to observe the DUT's ability to maintain bandwidth fairness. The topology change test tests the DUT's ability to properly react to changes in the emulated topology.

The forwarding performance test measures a DUT's ability to properly handle RPR QoS packet prioritization and forwarding. The tester should be able to simultaneously test for packet loss, sequence errors, average/min/max latency, latency variation and packet rate.

More Information on RPR
Within RPR is the concept of "spatial reuse" that allows the reuse of freed space to carry additional traffic, in contrast to SONET/SDH that takes up all of the bandwidth around the entire ring. Spatial reuse is possible because RPR eliminates the signal once the destination is reached.




RSVP


The Resource ReSerVation Protocol (RSVP) improves Internet architecture by supporting Quality of Service (QoS) flows. RSVP is used to request particular qualities of service from the network for application data streams. This transport-layer protocol defines how applications request resources for reservation and how resources are relinquished when not needed. It is used for multicast and unicast data flows.

Routers utilize RSVP for QoS requests and to establish and maintain the requested service. Requests allow the reservation of resources in each node along the data path. RSVP has been specified in RFC 2205 and RFC 2210.

RSVP Testing
RSVP interoperates with routing protocols but is not in itself a routing protocol. Testing procedures will depend on how it is used.

More Information on RSVP
RSVP is not usually found in modern telecommunications networks, though its traffic engineering extension or RSVP-TE is gaining acceptance for QoS and networks which must guarantee bandwidth.

The RSVP protocol takes into account that different applications will have different network requirements. Some traditional applications require a reliable delivery of data but impose no requirement on the time it takes to be received. Some of the newer applications, such as video conferencing and Voice over IP (VoIP), require almost the exact opposite. These applications require a timely delivery with much less emphasis on reliability.




SAN


Storage Area Networks (SAN) are designed to attach storage devices such as disk array controllers and tape libraries to servers. SANs are most commonly found in enterprise networks. A SAN allows a machine to connect to remote targets such as disks and tape drives on a network for block I/O. The devices are usually locally attached to the workstations.

SAN Testing
SAN equipment manufacturers should perform robust tests not only on hardware but on the protocols that will provide the transportation of data between the SANs and end systems. The bandwidth, I/O rate and latency should all be tested to determine if the SAN is able to handle the required work load. Verifying the data and the data's integrity (which has been sent across the network) also is important.

More Information on SAN
Currently, there are two variations of SANs. The first one is a network whose primary purpose is the transfer of data between computer systems and storage elements. A SAN consists of communication infrastructure that provides physical connections, a management layer that organizes the connections, storage elements and computer systems so that data transfer is secure and robust.

The second type is a storage system consisting of storage elements, storage devices, computer systems and/or appliances, plus all the needed control software for the communications that are sent over a network. The most common SAN protocol is Fibre Channel. Another newer SAN protocol ratified in 2003 is iSCSI. ATA over Ethernet is a light-weight, open-source SAN protocol.




SS7


Signaling System #7 (SS7) comprises telephony signaling protocols that set up most of the calls for public-switched telephone networks (PSTN ). Carriers use SS7 for telephony network signaling, interfacing, messaging and network maintenance. SS7 handles call establishment and handles exchanging user information, call routing and billing structure while supporting Intelligent Network (IN) services. The IN architecture is for fixed and mobile telecommunications and can be perceived as an overlay on the core network. It allows operators to offer value-added services in addition to GSM services on mobile phones.

SS7 is also important in linking VoIP traffic to the PSTN network. SS7 is utilized in mobile cellular telephony networks like GSM and Universal Mobile Telecommunications System (UMTS) for voice (Circuit Switched) and data (Packet Switched) applications.

SS7 is often referred to as CCS7, an acronym for Common Channel Signaling System 7. In some parts of Europe, SS7 is known as C7 as in the United Kingdom or even CCIS7.

SS7 Testing
The tester should be able to generate and respond to SS7 messaging required for setting up and tearing down small to large numbers of calls, and with and without actual bearer traffic.

Among the testing conducted on voice over packet networks should be testing the internetworking of legacy PSTN; analyzing performance under heavy load of voice calls; assessing the quality of service for voice, fax, and modem data; measuring one-way delay and round-trip delay for speech. For switches, central offices, service switching points (SSP) and signaling transit point (STP) nodes, testing should create traffic, verify routing and determine capacity.

Other testing can be performed for voice mail and voice response, and detection in the transmitting and receiving account codes, traffic to leave messages, and replay and verify messages.

More Information on SS7
The original SS7 protocols were developed by AT&T and defined as standard by ITU-T Q.7XX-series recommendations. SS7 was to take the place of Signaling System #5 (SS5) and Signaling System #6 (SS6) and R2. It has mostly replaced SS6 and SS5, but R2 variants are still utilized by several countries.




SSL


Secure Sockets Layer (SSL) is a cryptographic protocol that provides secure communications on the Internet for Web browsing, mail, Internet faxing and other data transfers. In typical SSL use, only the server is authenticated while the client remains unauthenticated. This allows the client/server to communicate in a way that will prevent eavesdropping, tampering and message forgery.

SSL involves three basic steps. The first one is peer negotiation for algorithm support. The second step is the public key encryption based key exchange and certificate-based authentication. The third is encrypting the data.

SSL Testing
SSL testing would require testing the affects of SSL on the network. As SSL encryption and decryption will put more stress on the end stations and servers throughput, and latency should be tested to determine how SSL will affect the network. As the data is being encrypted and decrypted, verifying the data at the end is essential as well.

More Information on SSL
SSL runs on layers beneath application protocols, such as HTTP, FTP and SMTP. SSL runs above the TCP or UDP transport protocol layer. SSL is most commonly used with HTTP, which is called HTTPS. HTTPS secures Web pages for applications like e-commerce. SSL can also be used to tunnel an entire network stack to create a VPN. SSL use is increasing as a larger number of client and server products are natively providing SSL support.




Streaming Media


Streaming media consists of audio and video that is divided into packets and transported over the Internet. It "streams" because a viewer or listener receives the sound or pictures as the packets arrive in contrast to downloading a song or video clip entirely before listening or watching the message. Prior to streaming media, files were delivered to the computer in their entirety before someone had the opportunity to listen or watch the program.

Media streaming can be categorized in two ways: live and on demand. Live means the stream is available at a certain designated time such as in an event or a meeting. On demand denotes that the stream is stored on a server, and it can be transmitted when the user requests it.

Streaming Media Testing
Certain protocols were designed specially to stream media over networks. They include the Real-Time Transport Protocol (RTP), Real-Time Streaming Protocol (RTSP), and the RTP Control Protocol (RTCP). Other protocols also work but may affect the network or performance in various ways and may be difficult to implement.

Many issues can arise when conducting streaming media over large networks and service deployment can raise significant issues. Testing should be conducted for scalability, Quality of Service (QoS), Quality of Experience (QoE) and for protocol performance to ensure that one or many users are offered the best possible performance.

More Information on Streaming Media
As streaming media is a continuous transmission over a period of time, should many workstations do this, the network will be affected. Due to bandwidth and other concerns, streaming video by many users utilizing that network can adversely impact the network's performance.




Switches


A network switch or switch is a piece of equipment that connects multiple network segments at full wire speed. A switch connects different packet-switched networking technologies with each other and operates at Layer 2 of the OSI model.

To perform the forwarding of packets when a packet enters it, the switch will look at the originating MAC address and port. The switch will then save this information into a table and send the packet out the correct port based on the destination MAC address. If the destination MAC address is unknown, the packet is sent out all the ports minus the originating one.

Switch Testing
Switches are becoming increasingly complex. Testing a switch involves testing its Virtual Local Area Network (VLAN) capabilities as well as performing different multicast registration protocol tests. Depending on how the switch will be used in the network, access control lists (ACL) might need to be tested along with the Spanning Tree Protocol (STP). Two RFCs have been created for testing switches, RFC 2544 and RFC 2889.

More Information on Switches
A switch has several different methods of forwarding data. The most common is store and forward. The switch will store the contents of the frame and perform a checksum on each frame before it actually forwards it on. The next method is cut through, where the switch will only read up to the hardware address before starting to forward it. No error checking is performed with the cut through method. The third method is Fragment Free, which reads the first 64 bytes of the frame where all the addressing information is stored. Reading the first 64 bytes will ensure the frame reaches the intended destination. Error checking in the method is left to the end device. The final method is Adaptive switching, and this method will switch between the three previously stated methods.




T-1


T-1 stands for Trunk Level 1 which is a digital transmission link at 1.544 Mbit/s and a standard for the United States, Canada and Japan. In addition to network access applications, T-1 can be utilized for private or leased line networking and is used for voice and data transmission between devices. Europe and other areas use E-1.

T-1, sometimes known as DS-1, is part of a series of transmission trunks also known as the Digital Signal Level hierarchy. For example, T-2 operates at a signaling rate of 6.312 Mbit/s and can handle up to 96 voice conversations, which is four times the capacity of T-1. T-3 operates at 44.736 Mbit/s and is equivalent to 28 T-1 lines. Meanwhile, T-4 supports 274.176 Mbit/s and handles 4,032 voice conversations, with 168 times T-1's capacity. It runs on coaxial cable, microwave radio or fiber optic and is mainly used for carrier backbones.

T-1 Testing
Testing should take into account the technology used on the network, which may include physical and logical layer testing. The tester should offer Asynchronous Transfer Mode (ATM) and Frame Relay analysis along with protocol decode functionality.

More Information on T-1
The T-1 digital transmission link in the mid-1990s was found mainly in the central offices of telephone companies for use in transmitting voice. However, cell-phone companies have been increasingly using it to connect to their central office switches and cell sites. In recent years, companies have begun using their own T-1s for access to the Internet. T-1 can be a channeled circuit for reserving channels transmitting non-data traffic.




Triple Play


Triple Play is a marketing term used to describe the use of voice, video and data over an IP-based network. The voice part of a triple play network is usually Voice over IP (VoIP), while the video part of triple play may contain Video on Demand (VoD) or regular broadcasts. These services are being offered by the cable television operators and telecommunication operators.

The simultaneous delivery of a voice (VoIP), video (IPTV) and data services presents complex challenges for service providers and Network Equipment Manufacturers alike. Key to their success will be to "get it right the first time" delivery of the triple play service bundle. A subscriber's quality of experience (QoE) is dependent on the performance of individual network devices, the appropriate network design, and the efficiency and accuracy of services management to successfully meet these challenges.

Triple Play Testing
Testing triple play would involve testing all three aspects. First, the core data network should be tested. These tests could involve any Layer 2 to Layer 3 tests. Perform the required tests best suited for your network configuration. Then, voice and video should be tested separately, making sure that both maintain the required quality. After each has been tested individually, they should all be tested together to determine the performance of the network under such a load.

Spirent's deep understanding of what it takes to deliver a successful, market leading Triple Play experience resonates across the entire service development and deployment environment. From the development and validation labs of both services providers and Network Equipment Manufacturers to the service centers and field operations challenged with delivery and management of the services, Spirent has the tools and technology to anticipate and assure your Triple Play subscribers QoE.

More Information on Triple Play
Offering bundled Triple Play services allows service providers to fully realize the capabilities of their existing wired infrastructure. There clearly isn't one solution for the many Triple Play permutations that involve infrastructure, applications and services, nor is there a "one size fits all" for testing or operating Triple Play networks. This makes testing Triple Play networks an interesting and complex task.

The term Triple Play has even led to the term "Quadruple Play." Quadruple Play has voice, video, data and wireless. The wireless uses CDMA and GSM standards.




UMTS


Universal Mobile Telecommunications Systems (UMTS) is one of the third-generation (3G) mobile phone technologies. UMTS uses Wideband Code Division Multiple Access (WCDMA) as the underlying standard. In theory, UMTS is able to support up to 11 Mbits/s data transfer rates though these rates have yet to be ascertained. UMTS was created to replace GSM.

UMTS Testing
In testing UMTS, the core network needs to be tested. As the core network will provide Layers 1 to 3, all of these aspects of the core network must be tested including switching and routing. Asynchronous Transfer Mode (ATM) also needs to be tested as this is used as the back bone of the core network. The UMTS Terrestrial Radio Access Network (UTRAN) needs to be tested, and WCDMA was chosen for the air interface. Both modes of WCDMA, Frequency Division Duplex (FDD) and Time Division Duplex (TDD) need their functionality determined.

More Information on UMTS
UMTS offers a variety of services. Some of the services offered are SMS and bearer services. These provide the capability for information to transfer between access points. Different bearer services have a different Quality of Service (QoS) value. There are four QoS values used in UMTS. The first one is the conversational class and this includes traffic of voice, video telephony and video gaming. The second one is the streaming class and includes traffic of multimedia, video on demand (VoD) and Web casts. The third is the interactive class and includes Web browsing, network gaming and database access. The forth and final is the background class and includes traffic types of e-mail, Short Message Service (SMS), and downloading.




UniPHY


UniPHY refers to a converged test solution. The term originated during the development of specifications for 10 Gigabit Ethernet and relates to the ability to support multiple physical layer technologies from the same interface. Specifically, UniPHY is an interface using multiple optics that can be switched between different line rates used by OC-192 and 10 GigE. It also entails support for multiple framing formats such as OC-192 Packet over SONET (PoS), 10 GigE LAN and 10 GigE WAN. These features provide a "Swiss Army knife" for 10 gigabit testing, avoiding the need to buy separate products to test 10 GigE and OC-192 PoS.

Ethernet is the undisputed leader of local area network (LAN) networking technology, with tens of millions of Ethernet switch ports deployed. The technology remains dominant for packet switching in the LAN while SONET owns the core, as Ethernet moves toward it.

UniPHY Testing
The demand for highly versatile and cost effective solution exists in the metro market, where Ethernet meets SONET. Testing interworking between Ethernet and SONET-based transport is important to service providers and equipment manufacturers.

More Information on UniPHY
A UniPHY test solution addresses the multi-dimensional requirements by providing a single module to test different transport technologies up and down the protocol stack.




VLAN


Virtual Local Area Network (VLAN) is a way of creating independent logical networks within a physical network. A VLAN is a logical network grouping that can be used to isolate network traffic so members of the VLAN receive traffic from only members on the same VLAN. VLANs can be used to group a set of related users, regardless of their physical connectivity. VLANs are usually configured in software, and this makes them extremely flexible.

VLAN Testing
The ability and functionality of VLANs should be tested. A single VLAN functional test should be run, and once this has been completed and verified a multiple VLAN functional test also should be run. As VLAN traffic will need to be routed, a routing test should be performed with a decent number of VLANs. Finally, as Quality of Service (QoS VoIP) is becoming more widely used, a high density VLAN QoS test should be run.

More Information on VLAN
Assigning users to a VLAN is accomplished in several ways. One way is port-based, which assigns users to the VLAN based on what port they are connected to on the device. The second way is MAC-based. The membership to the VLAN is dependent on the MAC address of the workstation. Third is protocol based, where Layer 3 VoIP data within the frame determines VLAN membership. The fourth way is authentication based. The devices can be placed on the VLAN automatically, depending on the authentication credentials of the users.




Voice Gateways


A gateway is an entry to and an exit from a communications network. The network could be small, as between one Local Area Network (LAN) and another. Or the gateway can connect very broad networks operated by major carriers. Within data networks, gateways are nodes that interconnect two disparate types of networks. For other types of networks, the gateway is part of the code and protocol conversion process.

In many cases, voice gateway capabilities include improved voice quality while handling latency and bandwidth requirements. The voice gateway relays voice and fax traffic across an Internet Protocol (IP) network while filtering out unwanted noise, among other functions such as interfacing with the Public Switched Telephone Network's (PSTN ) digital switches or PBX machines.

Testing is vital to address the effect of time varying impairments on device performance as well as the ability to test voice gateways when used with other converged services.

Voice Gateway Testing Solutions
The complex migration from legacy TDM to VoIP networks will require years of careful management. During the migration to converged networks, equipment manufacturers will face business and technical issues involving voice gateways. Integrated testing must verify converged network infrastructure for performance, interoperability and voice quality. Testing may include transitional PSTN to VoIP testing strategies, scalability and quality testing.

For voice and video testing over IP, tests should include scalability, performance and interoperability. Test solutions should enable conformance, functional and performance testing.

Comprehensive device testing should include voice quality (MOS, PSQM, PSQM+, PESQ, PESQ-LQ, J-MOS, R-Factor); the impact of data and video on voice in a Triple Play network; for testing interoperability of disparate devices and switching schemes including analog, TDM, and VoIP traffic.

More Information on Voice Gateways
A gateway may need to be used in an H.323 conference. H.323 is an umbrella recommendation from the ITU-T defining audio-visual communication session protocols on a packet network. H.323 is used in voice over IP and IP-based videoconferences. H.323 was created for transporting local area network multimedia applications, but it eventually was used for VoIP networks.




Voice/VoIP


Voice over Internet Protocol (VoIP) transmits voice conversation over a data network using the Internet Protocol standard. VoIP can either be implemented using a hardware system or be software based. If VoIP is going to be software based, a computer will be needed.

VoIP Testing
VoIP has many different elements that can be tested. Some of the major elements of VoIP that should be tested are call subscriber rate, and the setup and tear down of the calls. Also, voice quality at the receiving end should be tested. As people are accustomed to a certain level of quality, this level should be maintained. Other performance tests can be run as well. Tests should be run independently and then again with background traffic. Other VoIP testing is possible; these are examples.

More Information on VoIP
Even though VoIP is starting to become mainstream and increasingly used, some drawbacks still exist. One major drawback is complexity in transmitting a fax. Another drawback is during a power outage, one will not be able to make or receive calls. Also, with the implementation of IP, it is hard to geographically locate a user on a network. This makes emergency calls a problem as they can not easily be routed to a nearby call center.

As voice is high priority traffic, a Quality of Service (QoS) mechanism is needed. When UDP is used for VoIP transmissions and no QoS is available, latency and jitter problems are encountered.




WAN


Wide Area Networks (WAN) are computer networks that cover a large geographical area. The most will known WAN is the Internet. WANs connect Local Area Networks (LAN) so users in one location are able to communicate with users and computers in other locations. Many WANs are used for a single organization and are private. Other WANs built by Internet Service Providers (ISP) offer connections from an organization's LAN to the Internet.

WAN Testing
As WANs are created by connecting LANs together, packet routing will be required. Testing the routing protocol in a full meshed environment is needed to determine if each LAN is able to transmit and receive from one another. If other protocols or applications will be used across the WAN, these should also have an in-depth analysis performed.

More Information on WAN
There are several different ways to provide WAN connectivity. One way is by a leased line that will provide a point-to-point connection between two computers. This is a very secure way but is also expensive. A second method is by circuit switching where a dedicated circuit path will be created between end points. The third way is by packet switching that uses devices to transport packets by a shared point-to-point or point-to-multipoint link. Finally, the fourth is cell relay. This method is similar to packet switching but uses fixed-length cells instead of variable ones.




WAN Simulation


Network latency and signal degradation in enterprise WAN environments should be tested because as rich media content plays an increasingly large role in corporate communications, it's essential to ensure signal degradation does not interfere with system performance across the enterprise network.

Performance thresholds for latency-sensitive application-to-application traffic, voice over IP, video and streaming media applications have become more stringent. A comprehensive network testing strategy is now more important than ever since network complexity continues to evolve.

WAN Simulation Testing
Several considerations should be given to WAN simulation testing to investigate how the performance of WAN links affect remote user performance. For example, testing should be included to find answers whether applications are robust enough to handle network delay caused by the use of satellite links.

Other answers need to relate to whether queuing mechanisms are capable of compensating for delays and errors encountered in the WAN; can applications adjust to variations in network throughput and availability over time; will applications survive bandwidth limitations encountered in the WAN or on access links.

By testing prior to deploying business-critical applications, it is possible to ensure that application performance remains stable, even across global enterprise environments.

More Information on WAN Simulation
Latency in the enterprise WAN environment can be separated into two distinct categories: Latency occurring across large packet-based IP infrastructures such as corporate intranets or the public Internet; and, latency that occurs across long-haul bit transport systems as in coast-to-coast terrestrial links, trans-ocean links and satellite data links.




WCDMA


Wideband Code Division Multiple Access (WCDMA) is a 3G cellular network offering higher speed transmission protocol used in UMTS and in advanced 3G systems. WCDMA is a replacement for 2G GSM networks currently deployed worldwide and was accepted as part of the IMT-2000 family of 3G standards. WCDMA is an alternate to Code Division Multiple Access 2000 (CDMA2000), Enhanced Data Rates for GSM Evolution (EDGE) and short range Digital Enhanced Cordless Telecommunications (DECT) systems.

WCDMA Testing
In WCDMA testing, it is important to test the core network's throughput, latency and loss. Also, it is important to determine the quality of the calls since users expect a certain level of quality. With users roaming, making sure that handoffs are performed correctly and calls are not dropped is highly important. Both modes of WCDMA should be tested for determination of full functionality.

More Information on WCDMA
The radio channels in WCDMA are 5MHz wide. WCDMA also supports two modes of duplex. The first mode is frequency division and the second mode is time division. The current system uses frequency division, one frequency for uplink and another one for downlink. Also, WCDMA supports inter-call asynchronous operations. WCDMA supports the ability to use multi-user detection and smart antennas. These allow for an increase capacity and coverage. Multiple types of handoffs between cells are possible. Handoffs WCDMA can perform are soft handoff, softer handoff and hard handoff.




Web Application


A Web Application is a type of software that a Web browser accesses over the Internet or an intranet. This application has grown in importance because it can be maintained and updated without the required installation of new software on numerous computers used by clients. Web Applications, also known as Web apps, can implement webmail, work for retail purchases, various online activities, discussion boards, blogs and other uses.

Web Applications Testing
Users in enterprise systems need to access applications and data around the clock, which makes it mandatory for enterprises to ensure their applications and systems are performing properly regardless of the time of day, traffic volume or security attacks.

Testers for enterprise systems should be able to model realistic network conditions and heavy loads, emulate real users and realistic usage, simulate a virtually unlimited number of users, and size the network and server infrastructure to meet the enterprise's exact needs. In addition, testing should pinpoint problems with software and hardware before making costly purchases. Network defenses also should be tested and methods implemented to minimize security threats.

For government agencies, testing also should simulate a virtually unlimited number of real users in the most demanding traffic conditions through server load balancers and other devices.

More Information on Web Applications
A Web Application is usually built as a three-tiered application, but other variations are also workable. The Web browser often takes the first tier. The second or mid-tier is the engine that uses a dynamic Web content technology, and the third tier is the database. The browser initiates a request to the middle tier that in turn queries or updates against the database.




WiFi


Wireless Fidelity (WiFi) is a term for certain types of Wireless Local Area Networks (WLAN). WiFi uses the IEEE 802.11a/b/g specification. Recently, WiFi has gained a greater acceptance as an alternative to a wired Local Area Network (LAN) and is starting to appear in hotels, airports, coffee shops and other publicly accessible places. WiFi allows the user easy Internet connectivity to receive e-mail or just browse the Internet.

WiFi Testing
As WiFi depends on a radio to send and receive the needed data packets, the ability of the radio should be tested to make sure it is performing as expected. Depending on the WiFi setup being tested, making sure the correct routing and forwarding of packets to the correct WiFi-enabled device is important. As WiFi protocols exist with different throughput, testing the throughput and determining if it correctly meets the standard should also be performed.

More Information on WiFi
Several WiFi devices are available for use. A Wireless Access Point (WAP) will connect a group of wireless stations to a wired LAN nearby. Another device is the wireless router. This device integrates a WAP, IP router and a switch. A third device is the wireless Ethernet bridge that connects a wired network to a wireless network. A range extender is also available to increase the range of the current wireless network by its strategic positioning.

All major operating systems (Microsoft Windows, Apple OS X and Unix types) have varying levels of WiFi support and can use WiFi.




WiMAX


Worldwide Interoperability for Microwave Access (WiMAX) is a standard-based technology that delivers the last mile by wireless broadband access as an alternative to cable and Digital Subscriber Line (DSL). WiMAX is defined in IEEE 802.16. It improves on many WiFi limitations by providing increased bandwidth and range, along with more effective encryption.

WiMAX Testing
WiMAX network equipment or terminal devices should be comprehensively tested in a controllable RF environment. Testing should include effects such as multiple-input multiple-output (MIMO) transmission, time-varying multi-path delay spread.

More Information on WiMAX
WiMAX uses a scheduling algorithm that the subscriber only needs to compete once to gain initial entry into the network. After it has competed, it is allocated an access slot by the base station. The time slot can change but remains to the subscriber satiation, which means other subscribers cannot use that time slot. The scheduling algorithm is stable under an overload and an over-subscription. Also, the scheduling algorithm is a lot more bandwidth efficient. The base satiation is able to control the Quality of Service (QoS) parameters by balancing time slot assignments among the application needs.

Of the WiMAX standards, 802.16d and 802.16e, or Mobile WiMAX will probably generate the most interest.




Wireless Infrastructure


As wireless technology is always advancing and new standards being created, changes are continuous to the current wireless infrastructure. Current equipment used in wireless infrastructure are GPRS Gateway Support Node (GGSN) and the Serving GPRS Support Node (SGSN) nodes.

The GGSN and GPRS are used in the GPRS core network that also provides support for Universal Mobile Telecommunications System (UMTS) and 3G networks. Other pieces of the wireless infrastructure will include standard networking equipment such as switches, routers and cabling in addition to non-networking equipment such as a billing system that keeps track of usage.

The wireless infrastructure contains many different parts and must support many different standards such as WCDMA, CDMA2000, TD-SCDMA and possibly WiMAX.

Wireless Infrastructure Testing Solutions
Depending on the technology used, testing the wireless infrastructure can vary. Though it is recommended to test each component of the infrastructure on its own and then test the various pieces together to determine overall functionality. Also, the infrastructure will depend on a Layer 2 data link mechanism, which will likely be Asynchronous Transfer Mode (ATM). The core features of ATM should be tested to ensure they meet the required specifications needed to support the wireless infrastructure.




WLAN


Wireless Local Area Network (WLAN) is a connection between multiple computers without connection by wire. To perform the connection, radio communication is used to accomplish the task. A WLAN has the same functionality that a wired Local Area Network (LAN) has. WLAN makes use of the spread-spectrum technology based on radio waves to enable communication between devices in a limited area. This is also known as the basic service set. A WLAN gives users the ability to be able to move around and still maintain connection to the network.

WLAN Testing
As WLAN depends on a radio to send and receive the needed data packets, the ability of the radio should be tested to make sure it is performing as expected. Depending on the WLAN setup being tested, making sure the correct routing and forwarding of packets to the correct device is important. As different WLAN protocols exist with different throughput testing, the throughput and whether it correctly meets the standard should be tested as well.

More Information on WLAN
A WLAN offers users a variety of benefits, from cost efficiency to seamless integration with other networks. The installation and deployment is flexible, fast and very scalable. If a certain area does not contain a wired network, it is easy to set up and establish a WLAN in the area. During a major disaster, a wireless network has a greater chance of surviving than a wired network. Also, 802.11 WLAN, WiMAX, and 3G+ cellular networks all promise high bandwidth, global mobility, Quality of Service (QoS) and all have seamless integration with one another.

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