White Paper: 10 Gigabit Ethernet over Twisted Pair Copper Systems

Transcription

1 White Paper: 10 Gigabit Ethernet over Twisted Pair Copper Systems Asef Baddar, RCDD Principal Engineer / Applications Engineering Supervisor Leviton Network Solutions C/7 - #1928

2 Table of Contents Background 3 Application Usage 3 Topology and Cabling Challenge 4 Cabling Standards Role 4 Cabling Progress 5 Summary 6 extreme 10G 7 2

3 Background - LAN Speeds Ever-Increasing, New Systems Needed LAN speeds have migrated steadily upward from 100BASE-T in the early 1990s to 1000BASE-T (Gigabit Ethernet) in In June 2006, IEEE (Institute of Electrical and Electronic Engineers) ratified a new standard called 10GBASE-T through the Task Force 802.3an. Their charter was the technical development of a new Physical Layer (PHY) that will be defined for operation up to10 Gigabit per second over twisted pair copper links. 10GBASE-T will extend the Ethernet family with speeds 10 and 100 times greater, respectively, than current LAN speeds. The objective of the 802.3an standard is to provide support for: bit error rate (BER) 10 Gigabit/second data transmission over up to 55 meters of Class E cabling (Category 6) 10 Gigabit/second data transmission over at least 100 meters of Class EA (Category 6A) and Class F (Category 7) cabling Application Usage Typical 10 Gig users are: High-performance computing (HPC) clusters Data Centers Scaled-up, consolidated servers Real-time video streaming on Web servers Workgroups involved in data-intensive, collaborative activities such as digital imaging and editing, simulation and modeling, and CAD/CAM Patient Archiving and Communications Systems - PACS 3

4 Topology and Cabling System Challenges - Obstacles to Achieving 10G 10GBASE-T PHY will rely heavily on the previously developed IEEE BASE-T and 1000BASE-T standard topology and technology. 10 Gigabit per second (Gbit/s) will operate similar to the 1000BASE-T with full duplex channels over 4 pair cabling, with each pair supporting 2.5 Gigabit per second simultaneously in both directions. The main obstacle in achieving this goal will be the design and construction of a suitable cabling system. While it is the role of IEEE 802.3an to develop electronics and active equipment standards, it is the TIA (Telecommunications Industry Association) role to develop standards for cabling systems. Typically, IEEE members prefer to use an existing cabling standard, but in this case, the highest category of cables (CAT6) was not capable of supporting the full distance required by TIA (100 meters). Before a suitable cable system could be produced, a number of challenges had to be overcome. The first is Power Sum Alien NEXT (PSANEXT). PSANEXT refers to alien crosstalk generated by coupling from adjacent Category 6 cabling channels within the vicinity. The second is the extended frequency required by 10gig of up to 500 MHz, double the frequency required by Category 6. Distance limitations are due to alien crosstalk, and based on link/channel modeling, the TIA TR42.7 Cabling Task Group decided the following at its latest draft: 10 gig should run over Category 6 cabling up to 37 meters without mitigation 10 gig should run over Category 6 cabling between meters with some mitigation 10 gig running over Category 6 channels of 55 meters and above will require mitigation TIA cabling task group developed methods and procedures to address ANEXT mitigation on Category 6 UTP cabling. Category 6 Shielded and Class F (Category 7) cabling does not require any mitigation due to the shielding available in these cables that will protect from outside interference including that from adjacent cables. Cabling Standards Role New TIA Standards Per the request of IEEE 802.3an, the TIA TR42.7 Cabling Task Group has been working on two projects to meet the 802.3an objectives. They are as follows: TSB-155: Develop a Technical System Bulletin (TSB) to describe additional guidelines for installed Category 6 cabling to support the proposed 10GBASE-T standard. These guidelines are intended to provide additional information on the extended frequency transmission performance of Category 6 cabling from 250MHz up to 500MHz. This bulletin (which was approved for release in December 06) also characterizes Alien Crosstalk (ANEXT) and provides additional guidelines for field test methods and ANEXT mitigation. The recommendations are intended to assess the installed Category 6 cabling and determine if 10GBASE-T is feasible. 568-B.2-10: Addendum10 of 568-B.2 specifies the development of cabling, component specifications, and test procedures to support the operation of IEEE 802.3an 10 Gigabit Ethernet (10GBASE-T) over 100 meters of an Augmented Category 6 (CAT6A) cabling. The frequency characterization will be extended from 250MHz to 500MHz for increased available bandwidth. Estimated completion time is June

5 Cabling System Progress Design Changes, Testing for ANEXT Manufacturers have accepted the 10gig challenge and most have developed a new cabling system that will meet CAT6A requirements. These new solutions have necessitated sweeping changes in cabling system design, with the most apparent changes being made to the horizontal and patch cables. To overcome alien crosstalk (ANEXT), the cables will be larger, and may have various internal separators, or in some cases, an alternative construction design. Another challenge is testing for ANEXT, as testing a cable bundle is more complex than testing a singular cable as we do today with CAT6 and 5e links. TIA has devised a referee ANEXT test method that includes seven cables in a form of six-around-one to simulate a typical bundle (see Figure 1). Figure 1 The necessity of testing for ANEXT adds time to the already time-consuming process of field-testing. The process is streamlined somewhat when random bundles are selected for testing and the end user accepts the method of sample selection, but it remains a time, resource, and labor intensive process. Reputable manufacturers of 10gig solutions do their best to support end users, and perform the necessary ANEXT lab testing to verify compliance prior to shipment. This saves the end user valuable time and resources. The biggest change to the connector has been to its circuit board, where pins have been separated as much as possible. A few creative manufacturers have tried to mittigate ANEXT by creating a separation on the outside of the connector body. 10gig patch cord designs are similar to the horizontal cable design, except that we notice some manufacturers adding a floating shield to help mitigate alien cross talk. The greatest challenge in designing a 10gig patch cord is the size of the patch cable, as it is still required to fit in the standard plug. 5

6 Summary 10 Gigabit Ethernet is a dominant technology in the backbone for high intensive bandwidth networks. Gigabit Ethernet will be the dominant technology to workstations until low latency and high bandwidth applications that require 10 Gigabit Ethernet are deployed. Existing Category 6 UTP installations could possibly support 10 Gigabit Ethernet, but only for short distances, and will most likely require mitigation as specified in TSB-155. To save on material costs, well-intentioned contractors or end users will often choose to install CAT6 cabling in place of CAT6A cabling. Unfortunately, this practice often results in increased costs due to having to trouble shoot links, testing for Alien Crosstalk, etc. In order to get the system to pass, it may become necessary to switch many of the components to CAT6A. Therefore, Leviton recommends that end-users needing a 10Gig Solution should install a CAT6A cabling system. If CAT6 was previously installed (and a 10gig solution is required), then testing is a must, and following mitigation techniques for TSB-155 is crucial. 6

7 extreme 10G Leviton s 10G Solution Looking much like a typical connector, patch panel, and patch cord, the biggest changes to Leviton s 10G Solution are internal. The extreme 10G QuickPort connector (figure 2) features two important technologies. The Cone of Silence (COS) was developed to resist ANEXT between neighboring connectors. The second is Retention Force Technology (RFT) which helps ensure error free performance over the life of the system by reinforcing tine contacts, even when 4- or 6-pin plugs have been used. Leviton 10G Patch Panels are available in Standard, Angled, Recessed Angled configurations supporting 24- or 48-ports. When rack or closet space is tight, a High-Density 1RU/48-port panel is also available. All Leviton 10G Patch Panels are preloaded with extreme 10G connectors. Leviton extreme 10G Patch Cords are constructed using a flexible wire to ensure both adequate life and long-term channel integrity. extreme 10G patch cords are available in seven TIA/EIA 606-A compatible colors and feature color matched cords and boots. Patch Cords are available in six standard lengths, as well as custom lengths. Figure 2 Leviton nd St. S.E. Bothell, WA USA Phone: (800) Fax: (425) info@leviton.com Website: Leviton Canada 165 Hymus Blvd. Point-Claire, Quebec Canada H9R-1G2 Phone: (514) Fax: (514) International Customers Call Leviton Voice & Data International Sales Department Phone: (425) Fax: (425) intl@leviton.com 7