[145193] in North American Network Operators' Group
Re: Cisco 7600 PFC3B(XL) and IPv6 packets with fragmentation header
daemon@ATHENA.MIT.EDU (Christopher Morrow)
Fri Sep 30 12:44:42 2011
In-Reply-To: <4E85F071.80201@foobar.org>
Date: Fri, 30 Sep 2011 12:44:29 -0400
From: Christopher Morrow <morrowc.lists@gmail.com>
To: Nick Hilliard <nick@foobar.org>
Cc: nanog@nanog.org
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On Fri, Sep 30, 2011 at 12:38 PM, Nick Hilliard <nick@foobar.org> wrote:
> On 30/09/2011 17:30, Christopher Morrow wrote:
>> traceroute is really an example of 'packet expired, send
>> unreachable'... that, today is basically:
>> =A0 o grab 64bytes of header (or something similar)
>> =A0 o shove that in a payload
>> =A0 o use the src as the dst
>> =A0 o stick my src on
>> =A0 o set icmp
>> =A0 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 b=
y
> hardware on the asr1k. =A0I don't know if they are true. =A0 But you're r=
ight -
some platforms do some/all of this in hardware, yes. (I forget the matrix)
> it would be good to support this without resorting to hammering the routi=
ng
> engine. =A0I don't really like the idea of punters running traceroutes
> reducing my bgp convergence time.
this is exactly why punting anything NOT management and/or
routing-protocols should be banned. Thanks for making that point
explicitly.
-chris
