IEEE examines congestion management in LANs

The IEEE is continuing to study ways to standardize the control of congestion in Ethernet networks.

The standards body earlier this year established a congestion management study group to examine the problem and determine if the IEEE should create a standard for it within 802.3, and the group will meet again this month.

The idea is that throughput, latency and frame discards can be improved if you combine traffic differentiation with rate and flow-control enhancements, according to a presentation on the IEEE’s Web site.

If different types of traffic are treated differently by LAN equipment, you can get better performance for time-sensitive traffic. That is, you’d give the available bandwidth to some types while denying it to others.

For example, voice and video over IP, storage traffic, and inter-processor communications should all be given special consideration apart from the usual run-of-the-mill LAN traffic. It should be noted that a couple of those traffic types – storage and inter-processor communications – have arisen along with new data center technologies, where storage and server blades use Ethernet as their communications medium.

The congestion management study group is examining whether a standard should be established to define the means to differentiate among traffic types and specify the controls to support congestion management for the different types.

The group is in the very early stages. So far, it has for the most part focused on its own scope – deciding to provide a mechanism for rate limiting, for example, while also deciding not to mess with physical-layer specifications and maintaining compatibility with existing standards.

The group estimates that it would be mid- to late 2006 before a standard would be reached.