[188157] in North American Network Operators' Group
Re: Internet Exchanges supporting jumbo frames?
daemon@ATHENA.MIT.EDU (Tassos Chatzithomaoglou)
Thu Mar 10 09:43:43 2016
X-Original-To: nanog@nanog.org
From: Tassos Chatzithomaoglou <achatz@forthnet.gr>
To: nanog@nanog.org
Date: Thu, 10 Mar 2016 16:43:47 +0200
In-Reply-To: <20160310151555.65178a3d@pels-Latitude-E5450>
Errors-To: nanog-bounces@nanog.org
Martin Pels wrote on 10/3/2016 4:15 =CE=BC=CE=BC:
> 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 decisio=
n.
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 negotiat=
e
> 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
