[e2e] Number of persistent connections per HTTP server?

Spencer Dawkins sdawkins at cynetanetworks.com
Thu Oct 10 12:30:16 PDT 2002

Hi, Venkat,

It makes sense to me that, if spreading files across multiple servers to force more parallel direct persistent connections is useful, clients using proxies would also open more connections just to keep up.

I think the analogy becomes "if all the traffic goes on one highway, it should have more than two lanes".

I'm just looking for any empirical evidence that anyone is aware of, that "more than two lanes" is OK for deployment on the general Internet.


-----Original Message-----
From: Venkat Padmanabhan [mailto:padmanab at microsoft.com]
Sent: Thursday, October 10, 2002 1:30 PM
To: Greg Minshall; Spencer Dawkins
Cc: end2end-interest at postel.org
Subject: RE: [e2e] Number of persistent connections per HTTP server? 

I believe the reason the recommended number of persistent connections
per client was set to 2 rather than 1 was to prevent head-of-line
blocking. With a single connection (and in the absence of byte-range
requests), the transfer of a large object could block subsequent
requests for a significant length of time. With two connections, one can
confine the large transfers to one connection, keeping the other one
clear for short transfers. This is analogous to why a two-lane road is
far better than a single-lane one.


Venkat Padmanabhan
Microsoft Research
padmanab at microsoft.com

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