Interesting People mailing list archives
Re: Engineers fixing networks & IntServ
From: David Farber <dave () farber net>
Date: Tue, 29 Jul 2008 08:40:11 -0700
________________________________________ From: craig () aland bbn com [craig () aland bbn com] Sent: Tuesday, July 29, 2008 11:35 AM To: David Farber Cc: mo () ccr org Subject: Engineers fixing networks & IntServ Mike O'Dell observed:
that would have been "IntServe" the failed Integrated Services model promulgated in the IETF half a decade later which was never viable at at the scale of the Global "Big-I" Internet.
As the former co-chair of the IETF IntServ Working Group I think the failure had more important lessons than Mike suggests. I may be wrong, but my sense was that IntServ failed less due to scalability issues (which existed, but I think were solvable) than to the interesting paradox that we designed precisely what the majority of ISPs, user groups and vendors said they wanted -- namely the ability to reserve guaranteed bandwidth with sturdy delay bounds -- and discovered no one wanted the service badly enough that they'd pay what it cost to offer it. It was more cost-effective to buy more bandwidth. Even more important, from my perspective, was that the IntServ work was firmly grounded in some excellent theoretical work which strongly suggests that something like the IntServ solution is about as good as you can get. Lots of fascinating papers ground down into three sentences: Most (all?) of the packet handling schemes that give delay & bandwidth guarantees have been shown to be variants of what could be called a Demers-Keshav-Shenker-Parekh-Guerin system (as a field, we lack a name for it). And we can map between bitwise and packetwise schemes. So bits/packets, doesn't matter, you want guarantees, you're stuck in a result space people don't like. And, last I checked, all proposals for performance guarantees in the past 15 years (ATM, IntServ, etc...) have been, at their core, the same ideas. Which is why, when you read things about improving Internet service, you see lots of discussions of "priorities" and "improving" service without discussions of guarantees. We've been down the guarantees road and don't like the result. Craig ************************* Chief Scientist, BBN Technologies Outreach Director, GENI Project Office E-mail: craig () aland bbn com or craig () bbn com Phone: +1 517 324 3425 ------------------------------------------- Archives: https://www.listbox.com/member/archive/247/=now RSS Feed: https://www.listbox.com/member/archive/rss/247/ Powered by Listbox: http://www.listbox.com
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