Date: Thu, 12 Sep 1996 15:02:21 -0700 (MST) From: Terry Lambert <terry@lambert.org> To: fenner@parc.xerox.com (Bill Fenner) Cc: karl@mcs.net, terry@lambert.org, avalon@coombs.anu.edu.au, freebsd-hackers@freebsd.org, koshy@india.hp.com Subject: Re: SYN Resisting (fwd) Message-ID: <199609122202.PAA07685@phaeton.artisoft.com> In-Reply-To: <96Sep12.141252pdt.177595@crevenia.parc.xerox.com> from "Bill Fenner" at Sep 12, 96 02:12:50 pm
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> >Like you are probably ignoring source quench. > > Source quenches are deprecated by RFC1812. RFC1122 is still the host > requirements RFC so technically hosts must still pay attention to them, > but routers are not supposed to send them. > > 4.3.3.3 Source Quench > > A router SHOULD NOT originate ICMP Source Quench messages. > ... > DISCUSSION > Research seems to suggest that Source Quench consumes network > bandwidth but is an ineffective (and unfair) antidote to > congestion. See, for example, [INTERNET:9] and [INTERNET:10]. > Section [5.3.6] discusses the current thinking on how routers > ought to deal with overload and network congestion. I don't know the wire protocol in use, but I would suspect that if it's LD cable transport, that it's ATM without a committed rate. This would be, by definition, unreliable small datagram delivery (aka "leaky bucket"). ATM manages loss conditions not by committing rates, but by issueing source quench base on dropped packet counters. Yes, I know, ATM is annoying, but it is what the phone companies use for large links, and we are stuck with it. Other than that, I was a little peeved at blaming the US with the blanket statement that the loss was on the US end of things. Ignoring perfectly valid source quench requests (from *non*-ICMP ATM routers) is only one of the possibilites that could be considered before calling everyone managing NSP in the US incompetent. Frame Relay has the same source quench issues as ATM (or IPV6, for that matter), so it;s not clear where the blame lies. Terry Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers.
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