New Technology Developments and How They Impact Your Structured Wiring Choices

New Technology Developments and How

They Impact Your Structured Wiring Choices

VOIP

VOIP systems are currently being installed in enterprise networks at an increasingly rapid rate. Within the next 5 years, it is possible that more than 50% of new enterprise voice installations will be VOIP.

Most customers still use switched systems, which include a PBX on the premise, to send signals over the Public Switched Telephone Network (PSTN). These systems create a circuit with dedicated bandwidth for the user. This is commonly referred to as circuit switching.

VOIP systems treat voice signals like data. Internet Protocol (IP) is how computers communicate over the Internet and is significantly different than a circuit switched system. A conversation is converted into digital form, same as most circuit switched networks, but then the individual bits are combined into packets. Each packet has a header that con-tains the IP address for the receiving phone. The VOIP phone set receives the packets and converts them back into a voice message stream.

A major difference between a circuit and packet transmission system is that the packet system doesn’t have dedicated bandwidth. Each packet is transmitted independently and can actually take a different path to the destination. This is very bandwidth efficient but can impact Quality of Service (QOS). Early VOIP systems suffered from delays and dropped conversations due to retransmission of bad packets but significant improvements have been made to improve the latency of modern VOIP systems. Bit errors become a problem quickly when real time transmission is needed. There have also been issues with security, scalability, interoperability and available features with IP phone systems. With the potential problems why is there such an interest in IP telephony? There are many advantages that make solving these problems worthwhile. The flexibility of IP telephony to process calls is a key advantage. The incoming number can

be easily linked to databases and route the caller to the appropriate agent. Long distance calls can be routed over a corporation’s Wide Area Network (WAN) bypassing the PSTN entirely.

From a structured wiring perspective only one network needs to be maintained since all traffic travels over the data network. The initial installation of a converged voice and data network is significantly (30-60%) cheaper than installing two networks. With all of the communications lifeblood of a company flowing on a single network, the robustness and performance of the network is even more important. Since less cabling is required overall, it makes even more sense to install the best performance currently available which includes Category 6 in the horizontal layer and a high bandwidth backbone, preferably 50 micron LaserCoreTM

or singlemode LightScopeTM_{Zero Water Peak (ZWP) fiber.}

At this time the TIA 42.1 structured wiring group is working with IEEE to develop requirements for data grade twisted pair cabling used with IP telephony equipment. The DTE Powering Task Force is working on a document, TIA/EIA SP-4425-AD6, to provide this information to IEEE. It is apparent that key cabling attributes for VOIP are related to resistance and capacitance unbalance, where Category 6 has signifi-cant advantages over lower grades of cable. (See Chart A) IP Telephony is generating interest because of the

benefits garnered from converged access, management and administration. While there are many potential benefits, issues with security, capacity and QOS must be evaluated for each specific application. Before implementing VOIP make sure that the structured wiring infrastructure is robust and the hardware supplier has addressed any concerns regarding features, quality, security, migration path and cost. Those companies that implement VOIP wisely can see significant benefits and improved profitability of

their enterprise.

Structured wiring has come a long way since the days when Category 3 and the IBM Cabling system were state of the art. It’s hard to believe that this was little more than 15 years ago. When we look ahead ten years to 2016, it is difficult to forecast the applica-tions and network capacity needed for the enterprise but another factor of 10 isn’t hard to fathom.

Current architectures utilizing Category 6 to the desk and high bandwidth fiber backbones can easily deliver 1 Gigabit of network capacity to the user. The proposed development of even higher speed applications over copper cabling promise to increase those data throughputs up to 10 Gigabits. In addition to higher bandwidth requirements there are also new technology drivers impacting how a structured wiring system is designed. Voice Over Internet Protocol (VOIP) and in building wireless networks, such as IEEE 802.11 Ethernet LAN’s, should also be considered when planning a network infrastructure. The following sections discuss what technology developments are currently active and how they can impact the structured wiring choices for your enterprise.

IEEE 802.3 10GBase-T

The demand for higher data transmission rates over cost effective UTP cabling continues. Many members of IEEE rec-ognized this potential and are developing technology for delivering 10G over UTP cabling. At the IEEE 802 Plenary Meeting held November 10th through 15th, 2002 in Hawaii, a tutorial was organized on “10GBASE-T Challenges and Solutions” that considered a 10Gb/s Ethernet standard for unshielded twisted pair copper cabling. The follow up Call for Interest meeting included many interesting presentations on technical feasibility, broad market potential, and economic feasibility. At the end of the Call for Interest meet-ing, a vote to establish a study group was unanimous with 110 participants expressing support. Later in the week, the IEEE 802.3 working group and the IEEE Standards Executive Committee (SEC) unanimously approved the formation of an IEEE 10GBASE-T study group. This study group evaluated the feasibility of standardizing 10Gb/s Ethernet transmission over UTP horizontal cabling up to a distance of 100 meters. One hundred meters is currently the maximum distance specified in the TIA 568-B series and ISO/IEC 11801 build-ing cablbuild-ing standards for horizontal cablbuild-ing.

The study group had its first meeting in January 2003. At this meeting members discussed different 10GBASE-T pro-posals. Typically, IEEE 802.3 standards are specified to run over as much of the installed base of cabling as possible. The committee chose to evaluate Cat 5e or better cabling when setting up this study group. Since IEEE is an interna-tional standards body and likes to refer to other

international standards; therefore, ISO/IEC 11801: 2002 cabling classes are referenced. ISO/IEC 11801:2002 Class D and Class E are essentially the same as TIA/EIA 568-B Category 5e and Category 6. Class F is considered Category 7, but is not referenced in the TIA-EIA 568-B doc-ument. Category 5e was soon dismissed for consideration based on theoretical throughput capacity calculations. Category 6 or better cabling is now being considered for the

10 Gb application. The study group is now a working group, 802.3an, titled 10GBase-T.

The details of how the 10G systems will transmit such high data rates are almost complete. The objective is to optimize the Digital Signal Processing (DSP) capability of the trans-ceivers to assure the Bit Error Rate Requirement of 10 (-12) at data rates of 10Gb/s is met. Current models indi-cate a theoretical Shannon Capacity of approximately 18 GB/s is required to obtain an actual 10 Gb/s throughput. Shannon Capacity is a calculation based on signal to noise ratio and bandwidth. Noise sources similar to those found in a Gigabit Ethernet system will still be prevalent in a 10 Gb network. FEXT (Far End Crosstalk), NEXT (Near End Crosstalk), Alien Crosstalk (ANEXT and AFEXT) and Return Loss (RL) will all need to be accounted for as potential noise sources. As with the 1000BaseT Gigabit standard all 4 pairs are used for transmission of data. Multilevel encoding with aggressive NEXT, FEXT and RL cancellation is required to achieve 10 Gb throughput.

A decision at the January 2004 meeting determined that Category 6 and a yet to be specified augmented Category 6 (6A) would be the only UTP cabling supported. To accom-modate the proposed encoding schemes it was determined that cabling will be evaluated out to 500 MHz. It is apparent that Insertion Loss (IL), PSANEXT and PSAFEXT will be the biggest challenges to overcome. Category 6 has improved IL and ANEXT performance relative to Category 5e. It is recog-nized that Category 6 or better cabling is needed for the new standard to be a success. Alien Crosstalk and IL objec-tives for Category 6A supporting 100 meters are now estab-lished. The ISO/IEC and TIA cabling committees are expect-ed to support IEEE requests for additional information for Alien Crosstalk measurement methods and performance requirements for UTP cabling and components up to a fre-quency of 500 MHz. Addendum 10 to the TIA/EIA 568B.2 standard is currently in draft form and expected to become a

Cable Category Resistance Unbalance Mutual Capacitance

(Ω/100m) 20°C (%) (1KHz) 20°C 3 < 9.38 < 5 < 6.6nF/100m < 20.1 pF/ft 5e < 9.38 < 5 < 5.6nF/100m < 17.1 pF/ft 6 < 6.7 < 2.5 < 4.6nF/100m < 14.1 pF/ft

standard by early 2007.

An original objective of IEEE was for the installed base of Category 6 cabling to support a minimum of 55 meters. After completing some rigorous field testing, it appears that 37 meters is a more achievable goal. This information is being put into TIA/EIA TSB 155 as a guide to users. As mentioned earlier, developing 10 Gbit/s over UTP is very challenging. Cable, cords and apparatus must be carefully designed to work together at extended frequencies. Test methods and performance requirements for components are still under development. In particular, claims made for Alien Crosstalk performance can be very misleading. The most widely endorsed test measures the Power Sum ANEXT of 6 disturber cables around a single victim cable. Most compa-nies making claims of 10 Gb compliance do not specify the test method and ignore the impact of AFEXT. Using only internal noise sources, or a two cable test, minimizes the effect of Alien Crosstalk and overstates the Shannon

Capacity of the channel. It is very possible that these systems won’t be standards compliant once the requirements are finalized. To support 10 Gig to the desk, high bandwidth fiber is required for the backbone network. The recent 10 Gigabit Ethernet fiber standard provides several optical fiber media options including 50 and 62.5 micron multimode and singlemode fiber. It is likely that work on a 40 Gbit or higher speed Ethernet fiber standard will be initiated in the near future. CommScope Category 6A cabling is engineered to support a full 100 meter, four connector channel when tested using the rigorous 6 around 1 bundle test. IEEE 802.11 WIRELESS NETWORKS

Mobile phones have made instant voice communication commonplace in the business world and in our personal lives. Many people are looking for the same kind of mobility for their computing applications. Recent developments in wireless networking have made this a

relatively inexpensive addition to a state of the art network design. Bandwidth limitations keep wireless from becoming an exclusive transmission media and replacing fixed net-works. However, a wireless overlay in a building or campus enhances the work environment significantly and improves worker productivity.

The most common wireless networking systems utilize technology developed by the IEEE 802.11 standards body. The most common system used today is 802.11g, which operates in the 2.4 GHz ISM band. 802.11g operate at 11 or 54 Mbit/s. Common terms for these networks are Wireless Ethernet, or Wi-Fi which is a certification program administered by the Wireless Ethernet Compatibility Alliance (WECA). 802.11a products that operate at 5 GHz are known as Wi-Fi5. It is also compatible with earlier 802.11b systems. Chart B shows the current types of 802.11 prod-ucts, their frequencies and data rates.

COMPARISON OF 802.11 STANDARDS 802.11 systems consist of four major physical

components; a distribution system, access point, wireless medium and network stations. The distribution system is responsible for forwarding frames to their destination. In most products this component consists of a bridging engine and network cabling backbone used to connect access points in a network. Ethernet is used as the backbone network technology. Access points perform the wireless to wired bridging function that allows the stations (users) to access the backbone network via the wireless medium of choice. (See Chart B)

Systems designed for enterprise installation use Inter Access Point Protocol (IAPP) to allow roaming between access points in a network. At this time IAPP is proprietary so multivendor communication is not assured. Where access points and antennas are located is very dependent on the building or area that is served. Each building has it’s own RF “personality” due to noise sources such as microwave

Chart B: Comparison of 802.11 Standards

802.11 2 Mbps 2.4 GHz 1997 Standard. Rarely used now.

802.11 a < 54 Mbps 5 GHz Second version but products only recently available.

Not compatible with 802.11 b products.

802.11 b 11 Mbps 2.4 GHz Largest installed base.

802.11 g < 54 Mbps 2.4 GHz Most common for new installations.

ovens, cordless phones, electrical conduits or severe multipath interference. Access points should be at least 25 feet away from any strong interference sources. It is assumed that a stable, high capacity wired network is already in place.

There are two methods to connect access points to the network to assure mobility. One option is to build the wireless infrastructure in parallel with the wired infrastructure. In this configuration, access points are supported by separate switches, cables and connections to the network core. Virtual LAN’s (VLAN’s) can also be deployed to reduce the physical infrastructure. The access points can be placed on a separate VLAN from existing wired stations and the wireless VLAN is given its own IP subnet. The major advantage for a parallel network is the ease of config-uring access points to minimize interference with other sta-tions. Consult with a hardware supplier regarding the benefits of both network design approaches. (See Chart C)

Planning for adequate capacity and surveying the site thoroughly are critical to a successful deployment. An important factor to know is the data throughput expected.

If a higher capacity 802.11a system is chosen, a much denser antenna and access point spacing will be needed. The density of users is also critical. As more users log on to an access point, data throughput drops. The site survey will dictate how the building design impacts the spacing of antennas. A detailed site survey before cabling is installed will spot any major problems and allow you to provide adequate coverage.

A rule of thumb is one access point per 20-30 users. The chart below shows estimated coverage for a standard omni directional antenna using 802.11b protocol. 802.11a will need closer antenna spacing.

The site survey will evaluate the coverage of access points and optimize their location. Bit error rate testing should be done and based on that information the location and number of access points and antennas adjusted. If any particular applications are designated for use on the network they should be evaluated. (See Chart D)

Cabling to the access points should match up with the exist-ing structured cablexist-ing. A minimum of Category 5e is needed with Category 6 preferred. To connect access points between Chart C: Network Topologies

Office Type Maximum Coverage Radius

Closed Office 50 – 60 Feet

Cubicles 90 Feet

Large Open Areas 150 Feet

Outdoors 300 Feet

Note: 802.11a coverage is approximately 25% less.

buildings or for distances greater than 90 meters optical fiber should be used. Although most access points have built in antennas, it is usually desirable to add an external antenna. Coaxial cable is typically used to connect the external anten-na and this is an area not to scrimp on. A high attenuation coaxial cable can sap much of the signal strength; therefore, a low loss 50-ohm cable such as CommScope’s WBC series should be used. Since attenuation drops with increasing cable size, the cable should be sized based on the length of the cable run. At minimum WBC-200 should be deployed with WBC-400 a common choice. 802.11a systems operate at 5 GHz so cable attenuation will be higher and larger

cables should be specified. Some antennas can use twisted pair cable but coaxial is usually a better choice.

Adding a wireless infrastructure during construction minimizes the cost to add it later after the building is occupied. Once workers get used to the freedom a wireless network provides they will be unlikely to want to give it up. Criticisms of wireless systems typically focus on security but current technology addresses this issue and provides high levels of security where needed. A wireless overlay combined with a high performance wired infrastructure will optimize the productivity and performance of the workforce.

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