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

James Bensley jwbensley at gmail.com
Wed Feb 24 06:28:33 EST 2016

On 24 February 2016 at 09:23, Ball Bag <dan at peachey.co> wrote:
> On 24/02/2016 02:42, CiscoNSP List wrote:
>> Hi Everyone,
>> 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!)...

> Can you not set a consistent MTU across the network that you
> know will be supported on every core circuit?


I've been in that scenario where for example 9 out fo 10 links are
dark fibre or wavelengths but that last one is a layer 2 service form
a 3rd party. In such a case you neet to drop the MTU on all links to
the smallest supported value across all links.

Take control of your network, don't rely on the PTMUD, set a value you
know works (test every link).


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