[c-nsp] Cisco 7304 as a Border router

[Simon Leinen]

sthaug  writes:
>> >>IOS choices are pretty limited and the way Cisco is handling 12.2S is 
>> >>confusing. At least it does jumbo frames on the GbE ports which is 
>> >>better than a 7206VXR/G1.
>> > 
>> > 
>> > Really? We have multiple 7206VXR/NPE-G1 which handle jumbo frames on
>> > the GigE ports just fine. Both 12.0S and 12.2S.
>> 
>> I'd be interested to know the IOS revision for 12.2S (since I need IPv6).

> Sorry, 4470 is what we use (for compatibility with SDH/SONET links),
> and I tend to think of this as jumbo frames. If you need 9000 bytes
> or more, I haven't found a way to do this.

We have some 720{4,6}VXR with NPE-G1 running with 9K MTUs here:

$ grep 'mtu 9' `grep -l 'VXR - a 7200 router' configs/*.switch.ch`
configs/swiff2.switch.ch: mtu 9192
configs/swiff2.switch.ch: mtu 9192
configs/swiho2.switch.ch: mtu 9192
configs/swiho2.switch.ch: mtu 9192
configs/swimy2.switch.ch: mtu 9192
configs/swips2.switch.ch: mtu 9192
configs/swips2.switch.ch: mtu 9192
configs/swisg3.switch.ch: mtu 9192
configs/swiwi2.switch.ch: mtu 9192
configs/swiwi2.switch.ch: mtu 9192
configs/swiyv2.switch.ch: mtu 9192
configs/swiyv2.switch.ch: mtu 9192

The thing is that 9K MTU support is missing from some IOS versions.
We run 12.3T on the 7200s (don't ask).  The routers above all run
12.3(7)T, which did support 9K MTUs.  But 12.3(8)T-12.3(11)T don't.

If I understand correctly they'll be back in 12.3(12)T.

So presumably the situation is similar in 12.2S.  4470 is certainly
not a hardware limitation of the platform.
-- 
Simon.