Internet Exchanges supporting jumbo frames?

Thu Mar 10 14:43:47 UTC 2016

Martin Pels wrote on 10/3/2016 4:15 μμ:
> On Thu, 10 Mar 2016 08:23:30 +0200
> Tassos Chatzithomaoglou <achatz at forthnet.gr> wrote:
>
>> Niels Bakker wrote on 10/3/16 02:44:
>>> * nanog at 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