nanog mailing list archives

Re: Cisco 7600 PFC3B(XL) and IPv6 packets with fragmentation header


From: Nick Hilliard <nick () foobar org>
Date: Fri, 30 Sep 2011 17:38:09 +0100

On 30/09/2011 17:30, Christopher Morrow wrote:
traceroute is really an example of 'packet expired, send
unreachable'... that, today is basically:
  o grab 64bytes of header (or something similar)
  o shove that in a payload
  o use the src as the dst
  o stick my src on
  o set icmp
  o crc and fire

there's not really any need to do this in the slow path, is there?

there are unconfirmed rumours that icmp ping and traceroute are handled by
hardware on the asr1k.  I don't know if they are true.   But you're right -
it would be good to support this without resorting to hammering the routing
engine.  I don't really like the idea of punters running traceroutes
reducing my bgp convergence time.

Nick



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