[c-nsp] transport path-mtu-discovery - ME3600....too unpredictable to use?

Nick Hilliard nick at foobar.org
Wed Feb 24 14:35:18 EST 2016

CiscoNSP List wrote:
> Quick synopsis of our network, multiple pops, all connected via
> various 3rd party carriers, who all use differing MTUs, that can also
> "change" unexpectedly(Unavoidable unfortunately!)

MTU means _maximum_ transport unit, so if your underlying transport
network unexpectedly changes this so that the max transport packet size
decreases below the configured MTU on the layer 3 side, then you are
going to drop packets, end of story.

Your transport providers need to guarantee you a specific MTU and you
need to configure your router L3 interfaces with that number.


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