[e2e] Multiple TCP-friendly Sessions and Cong. Control in user-mode?

Joe Touch touch at ISI.EDU
Wed Apr 10 11:26:34 PDT 2002

Shivkumar Kalyanaraman wrote:
> So, I read the community consensus is that we do not care about
> per-user or process unfriendly provided we are per-connection
> friendly (and/or we cannot do anything about it anyway)...

I'm not sure I'd read that. The whole point of CM and 2140 is to do 
better than per-connection, or at least to allow applications to use 
multiple connections without incurring the behavior of multiple 
connections as a result.

>>It should act just like multiple TCP connections between the same pair.
>>It is per-connection friendly, but per-user or process unfriendly.
>>It's an argument for implementing congestion control where the
>>scheduling jitter is low. That can mean separating congestion control
>>from the protocol (CM), OR using in-kernel implementations of
>>coordinating protocols (RFC2140) OR using a real-time OS with less
>>scheduling jitter at the user level
> Sounds consistent. But, is this argument well recognized in the brave new
> world where applications run over UDP/RTP and do their own CC? Are
> application developers implementing congestion control at the app layer ?
> How far is the CM or other approaches gaining traction with end-system
> designers?

The incentive for being TCP friendly is competing with the incentive for 
individual application performance. It isn't clear that any alternate 
approach (to being greedy and using existing simple code to use multiple 
connections) will be widely-adopted until there is backpressure to do so.


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