[c-nsp] mpls mtu / ip mtu / ospf

[Phil Mayers]

Gerald Krause wrote:
> On one of my systems I need to have a greater Ethernet-MTU for MPLS 

What equipment? Some kit IIRC cannot set a lower IP MTU e.g. 3550? I 
could be wrong on that.

> but at the same time this system should be able to do OSPF with some 

Well, at the Cisco end you can:

int blah
ip ospf mtu-ignore

...but the Cisco may still transmit MTU!=1500 which may fox the other end.

> gear that doesn't support other MTU sizes then the default of 1500.
> 
> I wonder if
> 
> !
> interface fastethernet 0
>   mtu 1530
>   ip mtu 1500
>   mpls ip
> !

That's what you want - we have this on our 6500s:

int vlanX
   mtu 9212
   ip mtu 9100
   mpls ip