Intel NICs, Cisco, autoneg, and borken-ness

Neil Schelly neil at jenandneil.com
Mon Mar 13 13:50:01 EST 2006


On Monday 13 March 2006 01:30 pm, Michael ODonnell wrote:
> > For what it's worth the default traceroute on Unix-ish systems
> > uses UDP, not ICMP.  traceroute -I (capital "eye") would use ICMP.
>
> Que?  How does that work?  I only know about that bump-the-TTL-after-
> every-hop trick.

UDP packets also have TTL settings.  The response from the particular router 
that hits that TTL is still ICMP (time-exceeded), but the outgoing traffic is 
UDP.

man traceroute 

-N



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