[c-nsp] MTU monitoring

[sthaug at nethelp.no]

> We have a contractual MTU, which is low. We would like to use a higher one, as it's
> most of the time available on the provider network.
> 
> As the MTU changes don't happen that often, i was wondering if there was a way
> to use the highest possible value, but get an alarm as soon as this MTU value
> is not honored anymore by the service provider.

If the MTU change happens in the underlying L2 network, your only
option is to perform continuous monitoring yourself (using maximum
sized packets with DF set).

Personally I would absolutely not use a higher MTU than what your
contract guarantees - IMHO doing so is simply asking for trouble.

Steinar Haug, Nethelp consulting, sthaug at nethelp.no