10 Gbps Ethernet as a Fiber-only Platform

As soon as the Institute of Electrical and Electronics Engineers (IEEE) finalized the 1 Gbps Ethernet solution on fiber, they began work on the 10 Gbps Ethernet solution. In March 1999, a high-speed study group (HSSG) was formed to investigate the options and develop recommendations for the next Ethernet platform. The HSSG’s work was completed with the approval of the project approval request (PAR) for 10 Gbps Ethernet in January 2000 and the establishment of task groups in March 2000. The date for the last new proposal was July 2000, so now IEEE is in the process of defining and standardizing the approved proposals. In March 2001 the group sent out a working group (WG) ballot, with plans to complete the standard by March 2002. Unlike previous Ethernet work items, 10 Gbps has been approved as a fiber-only platform. While discussion did occur within the HSSG on copper solutions, specifically a 2.5 Gbps copper solution, the IEEE decided not to include any copper solutions for standardization. However, unlike other fiber Ethernet solutions, where there is only one solution for 10 Mbps and 100 Mbps and only two for 1 Gbps Ethernet, four solutions are being developed for 10 Gbps Ethernet. There are so many solutions because, while other Ethernet solutions have been primarily or exclusively targeted for the local area network (LAN), 10 Gbps Ethernet is not only being targeted for the LAN but also the metropolitan area network (MAN) and wide area network (WAN). This, combined with the fact that the higher data rates meant that the more cost-effective multimode solutions could only satisfy the inside building distances of LANs, resulted in the need for four potential solutions. While a great deal of work needs to be completed and details added prior to the anticipated publication date of March 2002, the goals and objectives of 10 Gbps have been established. Basically, IEEE has decided upon four optoelectonic solutions with five distance objectives established. For LANs, they have established distance objectives of 65 meters over multimode fiber and 300 meters over installed (existing) multimode fiber for inside building networks and 2,000 meters for campus networks. For the MANs and WANs, they have established both 10- and 40-kilometer distance objectives. The four optoelectronic solutions are comprised of three serial transmitter solutions and one wave-division multiplex solution. Each of these proposed solutions and the planned distances that they will support on various fiber types are discussed below and presented in the attached table. The IEEE does not plan to assign correlation between the application and the solution as I have done. This discussion is solely based on my own belief of anticipated market development. The solutions for the WAN and MAN are definitely going to be single-mode solutions, with the WAN envisioned to use a 1,550nm serial laser for distances from 2 meters to 40 km. The MAN is envisioned to use the 1,310nm serial laser for distances from 2 meters to 10 km. Two solutions are being developed based on the belief that the 1,550nm serial laser solution will be more expensive than the 1,310nm serial solution and therefore the 1,550nm solution will only be used for those distances greater than 10 km. For the campus backbone, defined as being between 300 and 2,000 meters, the solution once again is single-mode. The standard will have two solutions for this application space and it is unclear as which one may become the predominate solution. The two solutions are the 1,310nm serial laser described for the MAN plus a 1,310nm wide wave-division multiplexed (WWDM) solution. The two solutions differ in that the serial solution uses one laser to transmit the 10 Gbps signal, whereas the WWDM solution actually uses four lasers at slightly different wavelengths around 1,310nm, each laser operating at 2.5 Gbps. Both systems are two-fiber systems and the multiplexing occurs inside the optoelectronics. For the inside building backbone, defined as 300 meters or less, and for fiber-to-the-desk applications, the solution set will depend upon what fiber the customer has installed. On standard multimode fiber, either 62.5 or 50-micron having the required bandwidth of 500 MHzokm at 1,300nm, the solution set will be the same 1,310nm WWDM solution described for the campus. For new installations, the user may elect to use this same standard multimode fiber in conjunction with the 1,310nm WWDM or may elect to install a yet-to-be fully defined new 50-micron fiber using the optoelectronics described below. The final optoelectronics solution set is an 850nm vertical cavity surface emitting laser (VCSEL). At present, this solution set is envisioned for equipment connections within the equipment room primarily used for switch-to-server connections. The distance capability of the 850nm VCSEL for standard 62.5-micron (160 MHzokm at 850nm) is only 28 meters, but for standard 50-micron (500 MHzokm at 850nm) it is 86 meters. There is discussion and consideration being given to a high laser-bandwidth 50-micron fiber that could allow for distances up to 300 meters; however, tests methods and performance values are yet to be finalized either by IEEE or the Telecommunications Industry Association (TIA). While further updates will be needed and provided on 10 Gbps Ethernet, it appears that the IEEE is focused on providing a solution set over standard installed existing multimode fiber for distances up to 300 meters and that for distances greater than 300 meters—single-mode fiber will be required. BEAM is director of systems marketing at AMP NETCONNECT Systems. He can be reached at (336) 727-5784 or tebeam@tycoelectonics.com.

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