- From: Ben Laurie <ben@gonzo.ben.algroup.co.uk>
- Date: Fri, 31 May 1996 20:58:27 +0100 (BST)
- To: Jeffrey Mogul <mogul@pa.dec.com>
- Cc: ben@algroup.co.uk, http-wg%cuckoo.hpl.hp.com@hplb.hpl.hp.com
Jeffrey Mogul wrote: > > 'HTTP/1.1 servers SHOULD maintain persistent connections and use TCPs > flow control mechanisms to resolve temporary overloads, rather than > terminating connections with the expectation that clients will retry. > The latter technique can exacerbate network congestion.' > > On a practical note; how do I distinguish between an idle client, a dead > client, and one that is avoiding network congestion? Should the standard > give some guidelines? > > Actually, the real question is "how do I distinguish between an idle > client, a dead client, and one that can no longer be reached over > the network?" (Network congestion tends to result in slow but not > totally failed communication.) A host that detectably can't be reached over the network will produce a "host unreachable" response. An undetectable one is indistiguishable from a dead host or one that is avoiding network congestion (I think). > The answer to the real question is "you can't, so don't bother to try." > Treat them all the same: when you get tired of waiting, give up. Many > servers seem to use a timeout of about 20 minutes for this. 20 minutes seems like a very long time to tie up valuable resources. > I mean, you could use the TCP keepalive mechanism to disinguish between > idle clients and the other cases, but it's pretty pointless, and it's > not a good way to reduce network congestion. Agreed. Cheers, Ben. > > -Jeff -- Ben Laurie Phone: +44 (181) 994 6435 Freelance Consultant and Fax: +44 (181) 994 6472 Technical Director Email: ben@algroup.co.uk A.L. Digital Ltd, URL: http://www.algroup.co.uk London, England.
Received on Friday, 31 May 1996 13:45:21 UTC