[e2e] Number of persistent connections per HTTP server?

Joe Touch touch at ISI.EDU
Mon Oct 14 15:02:22 PDT 2002


Qiaobing Xie wrote:
> Joe Touch wrote:
> ...
> 
>>>I seem to missing some information on why muxing at the IP layer does away
>>>with priority inversion as opposed with muxing on the transport layer. Whose
>>>priority (and where) is inverted?
>>>This isn't clear to me. Could you elaborate a bit?
>>
>>See:
>>D. Tennenhouse, "Layered Multiplexing Considered Harmful", Protocols for
>>High-Speed Networks, 1989.
>>
>>Muxing is required at the IP layer. Adding muxing above it, inside the
>>application, creates a layering that can cause a number of problems.
> 
> Hmmm, this seems to put the HTTP application into a hopeless situation -
> not to mux, you get the head-of-line blocking problem that is
> practically harmful towards the web users' experience; to mux, you get
> the theoretical "harmful layered mux problems" (towards the network
> bandwidth efficiency, I guess) :-)

You keep assuming two worlds:
	1 TCP connection without muxing on top -> HOL
	1 TCP connection with muxing on top -> layered muxing

As I said in the reply to your earlier message, please _read_ RFC2140.
You don't need to use a single TCP connection, and the use of multiple 
connections can be done in a way that allows IP to mux properly without 
creating inappropriate network load.

joe






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