Are you being served? The road to 10G Part 5

In the final part of our series on 10G Ethernet, we look beyond 10G and wonder what future evolution to even faster standards will mean for the networking pro.

Although most of us haven't even begun to deploy 10G Ethernet, the backroom brigade is already working on the next speed hike. Making Ethernet perform faster than 1Gbps required dropping the CSMA/CD scheme which was specified in all previous versions of the protocol. However, hardly anyone actually used collision detection and avoidance with 1G Ethernet, as most of the switches operate in full duplex mode, therefore "owning" the link so there's no longer anything with which to collide. 10G Ethernet doesn't even bother - you can't possibly avoid a collision with other packets at these speeds so full duplex is the only way to travel.

For that reason 10G Ethernet moved a lot closer to the SONET protocols and early pre-ratification ports often re-used the optics and cables from SONET OC-192. The next faster SONET protocol is OC-768 which offers 40Gbps speed, and there is a fair degree of support from vendors to make that speed the target of the next generation Ethernet beyond 10G. But that breaks with tradition for Ethernet which has been stepping up by adding a zero ever since the protocol was invented. The newly-formed Ethernet Alliance would like to see 100Gbps as the next generation Ethernet partly to preserve that history, but also because they feel an order of magnitude is what's required to generate sufficient demand for any increase.

Vendors point out that demand for speeds beyond 10Gbps can be met by using multiple 10G Ethernet links today, for a far lower cost than they could hope to produce a 40Gbps offering, let alone 100Gbps. But that hasn't stopped them trying. Force10 has just been granted patents for its latest switched router backplane technology which is designed to cater for the 100Gbps Ethernet of the future. In fact, the company claims the switches can handle up to 5Tbps with each slot capable of 330Gbps. That sounds ludicrously fast, but at the rate of change within the networking industry we could soon come to regard it as nothing more than "adequate".

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