Re: Internet Exchanges supporting jumbo frames?

[Tassos Chatzithomaoglou <achatz () forthnet gr>]

Martin Pels wrote on 10/3/2016 4:15 μμ:
> On Thu, 10 Mar 2016 08:23:30 +0200
> Tassos Chatzithomaoglou <achatz () forthnet gr> wrote:
>
> > Niels Bakker wrote on 10/3/16 02:44:
> > > * nanog () nanog org (Kurt Kraut via NANOG) [Thu 10 Mar 2016, 00:59
> > > CET]:
> > > > I'm pretty confident there is no need for a specific MTU consensus
> > > > and not all IXP participants are obligated to raise their
> > > > interface MTU if the IXP starts allowing jumbo frames.
> > > You're wrong here.  The IXP switch platform cannot send ICMP Packet
> > > Too Big messages.  That's why everybody must agree on one MTU.
> > Isn't that the case for IXP's current/default MTU?
> > If an IXP currently uses 1500, what effect will it have to its
> > customers if it's increased to 9200 but not announced to them?
> None. Until someone actually tries to make use of the higher MTU. Then
> things start breaking.

I can understand the above issue. But as i said that's customer's decision.
Exactly the same will happen if the customer increases its mtu now.
> In order for Jumboframes to be successful on IXPs _on a large scale_
> the technology has to change. There needs to be a mechanism to negotiate
> MTU for each L2 neighbor individually. Something like
> draft-van-beijnum-multi-mtu-03, which was mentioned before in this
> thread. With this in place individual sets of peers could safely use
> different MTUs on the same VLAN, and IXPs would have a migration path
> towards supporting larger framesizes.

Agreed. But that doesn't forbid the IXPs to use the max MTU now.


--
Tassos