[c-nsp] big system mtu in switches: what are the caveats?

Dmitry Cherkasov doctorchd at gmail.com
Mon Feb 27 08:46:22 EST 2006

Hi everybody,

Cisco Catalysts like 6550, 3560, 3750, etc. allow setting big system
mtu in order to implement sevices like q-in-q. MTU value may be set up
to 1998 on FastEthernet and up to 9000 on GigabitEthernet.

I wonder, what may be the caveats of setting mtu to its maximum (so it
is definitely not necessary to increase it in the future)? I am not
afraid of any fragmentation issues as all the segments connected to
the switch usually have agreed mtu. Are there any impacts on the
switch operation (memory allocation or anything alike)?
Dmitry Cherkasov

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