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

Christopher Morrow morrowc.lists at
Fri Sep 30 14:09:54 UTC 2011

On Fri, Sep 30, 2011 at 6:02 AM, Saku Ytti <saku at> wrote:
> On (2011-09-30 01:55 -0400), Christopher Morrow wrote:
>> when will vendors learn that punting to the RE/RP/smarts for packets
>> in the fastpath is ... not just 'unwise' but wholesale stupid? :(
> What to do with IP options or IPv6 hop-by-hop options? What to do with IPv6
> packets which contain options which push TCP/UDP past your lookup view?

a switch to be used that stops processing this sort of thing, in an
internet core (and honestly most enterprise core) routers, all I want
is packet-in/packet-out. there's no need for anything else, stop
trying to send line-rate packets to the cpu.

> Punting transit is not only not stupid but also necessary in hardware routers
> which cannot handle every case in hardware (which is all routers).

no. all you need is a default 'do not process these, just fwd them'
switch. (or, a switch at any rate that the operator can select one way
or the other, they SHOULD know what is the best for their deployment).

> There should just be adequate way to limit these and there should exist default
> limitation.

I really think zero limit is the right limit... (for a large number of

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