MTU to CDN's

Vincent Bernat bernat at
Tue Jan 9 08:11:55 UTC 2018

 ❦  8 janvier 2018 15:08 -0800, joel jaeggli <joelja at> :

>> N00b here trying to understand why certain CDN's such as Cloudfare have
>> issues where my MTU is low. For instance if I am using pptp and the MTU is
>> at 1300 it wont work. If I increase to 1478 it may or may not work.
> PMTUD has a lot of trouble working reliability when the destination of
> the PTB  is a stateless load-balancer.

More explanations are available here:
Don't comment bad code - rewrite it.
            - The Elements of Programming Style (Kernighan & Plauger)

More information about the NANOG mailing list