MTU to CDN's

Tue Jan 9 01:49:24 UTC 2018

CDN’s (or anyone using a load balancer to multiple server instances) needs to
assume that traffic may be encapsulated (4in6, 6in4, 464XLAT) and lower the
interface MTU’s so that all traffic generated can be encapsulated without
fragmentation or PTB’s being generated.

This is only going to get worse as more and more eyeballs are being forced
into using IPv4 as a service scenarios.

> On 9 Jan 2018, at 11:54 am, Jared Mauch <jared at puck.Nether.net> wrote:
> 
> On Mon, Jan 08, 2018 at 05:55:55PM -0500, Dovid Bender wrote:
>> Hi,
>> 
>> 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.
> 
> 	I've done some measurements over the internet in the past year or
> so and 1400 byte packets with DF bit seem to make it just fine.
> 
> 	- Jared
> 
> -- 
> Jared Mauch  | pgp key available via finger from jared at puck.nether.net
> clue++;      | http://puck.nether.net/~jared/  My statements are only mine.

-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742              INTERNET: marka at isc.org