[e2e] Number of persistent connections per HTTP server?

Joe Touch touch at ISI.EDU
Mon Oct 14 16:48:20 PDT 2002

Vadim Antonov wrote:
> On Mon, 14 Oct 2002, Joe Touch wrote:
>>D. Tennenhouse, "Layered Multiplexing Considered Harmful", Protocols for 
>>High-Speed Networks, 1989.
> David Tennehouse is very concerned with cross-talk, which is not the issue
> with parallel TCP sessions, so the only reason why not to multiplex N TCP
> sessions into one between the _same hosts_ is fairness,

The paper discusses the problems with even setting the QoS parameters of 
a low-level packet, when it is composed of multiple chunks of transport 
layer data with conflicting QoS requirements.

Further, when each application gets to set its own muxing mechanism and 
priority schemes, there can be conflicts. E.g., when one decides that 
audio is more important than data, and the other decides the converse.

> Doing multiplexing within single TCP session effectively shares the timing
> and congestion control information between flows, which is a good thing
> (this can be achieved by storing that info on per-peer-host basis in the
> TCP stack, instead of TCBs - however, this technique breaks down in case
> of NATs which can make different boxes appear to be the same box, or in
> case of per-flow load sharing in the network).

Since the NAT likely shares the majority of the path that determines RTT 
and bandwidth, it won't hurt sharing.


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