The Great Gigabit Backplane Shootout - Comments
SerDes vendors are involved in both the copper-base and optical-based backplane solutions. Optical links are best suited for long distance interconnects such as between boxes. However for short distance links between line cards, copper medium such as IB/CAT5/CAT6 cables are more cost effective. In either case, the SerDes (integrated or discrete) is needed for higher layer logic to process the signals.
There is a call of interests in IEEE in an effort to standardize 10GE over copper (IB4x). This effort is currently known as 10G-BaseCX-4.
The most common communications system architecture today makes use of a multi-layer copper backplane, connectors, and a number of cards. One to two of these cards are normally used for fabric switching and supervision. The others are linecards that handle the ingress and egress of data for the chassis. Each linecard usually has the ability to transmit and receive to primary and redundant fabric cards, thus, increasing each card's total backplane bandwidth requirement. Once a line card's total bandwidth exceeds 10 Gb/s, faster backplane transceivers are needed due to tradeoffs in mechanical aspects of the design (i.e. too few signal pairs available, space constraints), and backplane PCB limitations.
As noted in the trade press, newer router systems from Cisco and Juniper support total linecard bandwidths of 40Gb/s or greater. Many other manufacturers are also starting to investigate their architectural needs for next generation networking and telecom equipment. At these higher data rates, next generation backplane transceiver solutions will be required to overcome numerous channel impediments and to offer designers an upgrade path for both legacy and future demands.