[nsp] OSPF & Encryption

[atticus at satanic.org]

> One problem with using a IP MTU of 1500 on the tunnel interfaces is that the
> receiving end will process switch any packets that need to be reassembled.
> This can seriously impact your performance, so take care in doing this.

Correct, hence:

> > but since you'll own both end of the serial interfaces, you can bump
> > this up so that you can effectively maintain an end-to-end 1500 mtu..

Since the application was a back-to-back tunnel across a serial interface,
the mtu on the serial could be trivially increased to accomodate the
encapsulation overhead.