Re: MTU

[Mark Tinka <mark.tinka () seacom mu>]

On 22/Jul/16 15:42, Chris Kane wrote:

> My experience has been making a view phone calls and agreeing on 9,000
> is simple enough. I've only experienced one situation for which the
> MTU must match and that is on OSPF neighbor relationships, for which
> John T. Moy's book (OSPF - Anatomy of an Internet Routing Protocol)
> clearly explains why MTU became an issue during development of that
> protocol. As more and more of us choose or are forced to support
> 'jumbo' frames to accommodate Layer 2 extensions (DCI [Data Center
> Interconnects]) I find myself helping my customers work with their
> carriers to ensure that jumbo frames are supported. And frequently
> remind them to inquire that they be enabled not only on the primary
> path/s but any possible back up path as well. I've had customers
> experience DCI-related outages because their provider performed
> maintenance on the primary path and the re-route was sent across a
> path that did not support jumbo frames.

DCI links tend to be private in nature, and 100% on-net or off-net with
guarantees (NNI).

The question here is about the wider Internet.

> As always, YMMV but I personally feel having the discussions and
> implementation with your internal network team as well as all of your
> providers is time well spent.

I don't disagree.

The issue comes when other networks beyond your provider, and their
providers/peers, whose providers/peers, and their providers/peers, is
something you cannot control.

This falls into the same category of "Can QoS markings be honored across
the Internet" cases.

Mark.