Difference between "mtu" and "ip mtu"

[pkhatri]

Hi all,

Appreciate if someone could shed some light on this. When configuring the MTU on an interface using the "mtu" command, does the specified MTU serve as a default for all L3 MTUs or is that supposed to be an absolute maximum MTU ? E.g. can we specify an IP MTU using "ip mtu" that is larger than what is configured using "mtu" ?

Cheers,

Paresh.

[gurkang]

hi,

some platforms like 7500 series, are not accepting mtu command for fastethernet interfaces. If you use the box for mpls, you have to set mpls ip mtu for label positioning. In this case you can change the IP mtu without changing interface mtu. but I don't know any other case about this kind of change.

regards,