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Re: large organization nameservers sending icmp packets to dns servers.
On Mon, 06 Aug 2007 12:13:03 EDT, "Steven M. Bellovin" said: > > 1) ICMP is handled at the same rate as TCP/UDP packets in all the > > routers involved (so there's no danger of declaring a path "slow" > > when it really isn't, just becase a router slow-pathed ICMP). > > This is aimed at hosts, not routers, right? As far as I know, routers > don't slow-path forwarded ICMP. Hosts will probably reply to ICMP from > their kernel, so it's a faster response than a user-level DNS reply. Well, they don't *directly* slow-path it. But we've seen *plenty* of cases of "multi-hop performance as indicated by ICMP Echo Request/Reply doesn't at all match throughput/latency as indicated by TCP-level stats" mentioned on this list...