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.