Friday, March 30, 2007

CEE-ing into Ethernet silicon

Thanks to Patricia Thaler, chair of the IEEE 802.1au group on congestion management, for helping me peer a little deeper into the silicon horizon for Convergence Enhanced Ethernet. The new twist on Ethernet for the data center just emerged into the public this week. Based on discussion with Thaler it seems reasonable that a CEE spec might not get fleshed out until 2008 and chips might not hit until 2009.

Thaler hopes the .1au group picks one of four proposals for congestion management at a July meeting and develops a fairly solid spec by November. "It’s a reasonably complex problem," Thaler said, with a five-person simulation group meeting weekly to iron out issues.

The .1au effort could pave the way for work on specs for priority scheduling and priority-based pause by 2008, she estimated. Most Ethernet silicon already has priority scheduling in the form of weighted round robin schemes, but new hardware support will be needed for congestion management and priority-based pause, she added.

Separately, Thaler expressed concern that IBM seems to be breaking ranks with other iSCSI advocates with its plan to ask the T11 group on Wednesday to start work on Fibre Channel over CEE. Personally, my take is IBM chief engineer Renato Recio is trying to play both sides against the middle to get Fibre Channel and iSCSI going over CEE so in the end its storage on Ethernet no matter who wins.

"I don’t think its time to give up on iSCSI, it's promising," said Thaler, a senior principal engineer at Broadcom. "I don’t think you get things done by changing when things are going slow to something else. In Broadcom we are strong supporters of iSCSI," Thaler told me.

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