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

Mohacsi Janos mohacsi at niif.hu
Fri Sep 30 10:38:06 CDT 2011



On Fri, 30 Sep 2011, Nick Hilliard wrote:

> On 30/09/2011 15:45, Christopher Morrow wrote:
>> traceroute could certainly be handled in the fastpath.
>
> which traceroute?  icmp?  udp?  tcp?  Traceroute is not a single protocol.
>
>> what is that limit? from a single port? from a single linecard? from a
>> chassis? how about we remove complexity here and just deal with this
>> in the fastpath?
>
> on a pfc3, the mls rate limiters deal with handling all punts from the
> chassis to the RP.  It's difficult to handle this in any other way.
>
>> My point in calling this all 'stupid' is that by now we all have been
>> burned by this sort of behavior, vendors have heard from all of us
>> that 'this is really not a good answer', enough is enough please stop
>> doing this.
>
> "This is a Hard Problem".  There is a balance to be drawn between hardware
> complexity, cost and lifecycle.  In the case of the PFC3, we're talking
> about hardware which was released in 2000 - 11 years ago.  The ipv6
> fragment punting problem was fixed in the pfc3c, which was released in
> 2003.  I'm aware that cisco is still selling the pfc3b, but they really
> only push the rsp720 for internet stuff (if they're pushing the 6500/7600
> line at all).

They are pushing sup2T - however more for enterprise ip layer (6500 
series).
 	Regards,
 		Janos Mohacsi




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