* IEEE 802.3ar task force focused on congestion management
One task force in the IEEE that I haven’t yet discussed is the group looking at bringing better congestion management to Ethernet.
Following the usual route, the congestion management study group graduated to task force in December, with the intent of forming a standard way of communicating congestion information. Its designation is 802.3ar.
Specifically, the task forces objectives are, to quote from the group’s Web site:
* Specify a mechanism to support the communication of congestion information.
* Specify a mechanism to limit the rate of transmitted data on an Ethernet link.
* Preserve the MAC/PLS service interfaces.
* Minimize throughput reduction in non-congested flows.
The group was formed out of a concern that a growing number of applications are sensitive to frame delay, delay variation and loss. It says that proper congestion management could help increase throughput and reduce delay and frame loss.
The group points out that the current standard provides for a means of flow control – but while that mechanism can reduce frame loss, it can also increase delay and spread congestion, so it is rarely used.
The task force is obviously still in its early stages. In a meeting last month, the group heard presentations on rate limiting and congestion in Ethernet backplanes and considered proposals. In coming months the process of creating drafts and commenting on them gets underway.
It will be interesting to see what comes of this effort, which may continue through mid-2006.
