[c-nsp] Suspect MTU Issues

[Peter Rathlev]

On Tue, 2011-07-12 at 19:46 +0000, Leigh Harrison wrote:
> A link between two of the data centres is a dark fibre between two
> Cisco 3750E switches running on the ten gig ports with a variety of
> vlans passing over a dot1q trunk [and they] have a standard system mtu
> of 1500.
> [...] Sending packets of 1496 bytes over the mpls works just fine, but
> when I push 1497, it doesn't work - hence my thoughts of an MTU issue.
> 
> Have we fallen into a silly trap or is there a straightforward
> solution?  Is this an MTU problem or am I clutching at straws?

It does sound a lot like an MTU issue. Is there any reason why you don't
just raise the system MTU on the 3750E switches? It takes a reload to
activate but is otherwise quite uncomplicated, "system mtu jumbo 9198"
in global-config.

-- 
Peter