[nsp] Re: RPF problem with ICMP unreachables

Gert Doering gert at greenie.muc.de
Mon Mar 17 13:39:54 EST 2003


On Mon, Mar 17, 2003 at 01:15:58PM +0200, Hank Nussbacher wrote:
> A Cisco router running 12.2(12a) may send ICMP unreachable
> with the source IP address set to the IP address of the interface
> on which the non-routable packet arrived instead of the IP address
> of the outgoing interface towards the other box.

I always thought that this was a *feature*, not a bug.

For traceroute, it's much more useful to see the ingress interface of the
original IP packet that caused a "TTL exceeded" ICMP than to see the
egress interface - which might point a into totally different direction
if the routing is asymmetric.

USENET is *not* the non-clickable part of WWW!
Gert Doering - Munich, Germany                             gert at greenie.muc.de
fax: +49-89-35655025                        gert.doering at physik.tu-muenchen.de

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