Messages in this thread | | | Subject | Re: 2.2.2-ac7 TCP ignores ICMP host unreachable ?? | Date | Thu, 04 Mar 1999 02:14:07 +0100 | From | Rob van Nieuwkerk <> |
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> > But my memory tells me this: > > > > - Host Unreachable should be ignored for an *existing* TCP connection > > (it is considered an transient error) > > - Host Unreachable should make a TCP connection *setup* fail > > Its a heuristic some systems use. It breaks horribly on certain kinds of > ISDN dial on demand networks, and the RFC says its a temporary error
Hi,
OK, I can see the ISDN dod problem. But one could argue that these routers shouldn't send an ICMP Destination Unreachable for a packet that *can* be delivered. It just takes some actions (eg. bringing up the link) to accomplish it, but the destination *is* reachable ..
I did some quick RFC-1122 scanning. It says "TCP MUST NOT abort the connection" (in case of a ICMP Destination Unreachable). But there is no connection yet. Well at least not an *established* connection.
Anyway, I remember going through this some years ago and finding explicit RFC indications for the second heuristic. I'll try to find it. Maybe I'm wrong. If I find something I'll be back. Otherwise I'll shut up :-)
Greetings, Rob van Nieuwkerk
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