[c-nsp] mtu issues on 3750

[sthaug at nethelp.no]

> Have you tried configuring IP MTU on SVI/L3 interface?

Won't work. This is a known limitation of using the 3750 for L3. It
works fine with large MTUs for L2, but not for L3.

Steinar Haug, Nethelp consulting, sthaug at nethelp.no

> 
> Tassos Chatzithomaoglou wrote:
> > 3750 switches are said to support mtu > 1500 (1500-9000) on all GE ports 
> > according to this:
> > 
> > http://www.cisco.com/en/US/products/hw/switches/ps700/products_configuration_example09186a008010edab.shtml#c3
> > 
> > 3750#sh system mtu
> > 
> > System MTU size is 1500 bytes
> > System Jumbo MTU size is 1600 bytes
> > 
> > Routed port
> > -----------
> > 3750#sh int g1/0/10
> > GigabitEthernet1/0/10 is up, line protocol is up (connected)
> >    MTU 1600 bytes, BW 1000000 Kbit, DLY 10 usec,
> > 
> > 3750#sh ip int gi1/0/10
> > GigabitEthernet1/0/10 is up, line protocol is up
> >    MTU is 1500 bytes
> > 
> > SVI
> > ---
> > 3750#sh int g1/0/10
> > GigabitEthernet1/0/10 is up, line protocol is up (connected)
> >    MTU 1600 bytes, BW 1000000 Kbit, DLY 10 usec,
> > 
> > 3750#sh ip int vlan 99
> > Vlan99 is up, line protocol is up
> >    MTU is 1500 bytes
> > 
> > 
> > So you can't have L3 mtu > 1546 (= system mtu) if the GE ports are configured as 
> > L3 (Routed/SVI) ports. Any idea how to overcome this?
> > 
> > --
> > Tassos
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> > 
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