Re: Internet Exchanges supporting jumbo frames?

[Stefan Neufeind <nanog () stefan-neufeind de>]

There is no way to avoid breaking MTU for IPv4 but use PMTUD for IPv6,
is there? Meaning to stick to 1500 for IPv4 and use something larger for
IPv6?


Kind regards,
 Stefan

On 09.03.2016 15:59, Kurt Kraut via NANOG wrote:
> Hi Mike,
>
> The adoption of jumbo frames in a IXP doesn't brake IPv4. For an ISP, their
> corporate and residencial users would still use 1,5k. For datacenters,
> their local switches and servers are still set to 1,5k MTU. Nothing will
> brake.  When needed, if needed and when supported, from a specific server,
> from a specific switch, to a specific router it can raise the MTU up to the
> max MTU supported by IXP if the operator know the destination also supports
> it, like in the disaster recovery example I gave. For IPv6, the best MTU
> will be detected and used with no operational effort.
>
> For those who doesn't care about it, an IXP adopting jumbo frames wouldn't
> demand any kind of change for their network. They just set their interfaces
> to 1500 bytes and go rest. For those who care like me can take benefit from
> it and for that reason I see no reason for not adopting it.
>
>
> Best regards,
>
> Kurt Kraut
>
> 2016-03-09 11:53 GMT-03:00 Mike Hammett <nanog () ics-il net>:
>
> > Maybe breaking v4 in the process?
> >
> > -----
> > Mike Hammett
> > Intelligent Computing Solutions
> > http://www.ics-il.com
> >
> >
> >
> > Midwest Internet Exchange
> > http://www.midwest-ix.com
> >
> >
> > ----- Original Message -----
> >
> > From: "Kurt Kraut via NANOG" <nanog () nanog org>
> > To: "Nick Hilliard" <nick () foobar org>
> > Cc: "NANOG list" <nanog () nanog org>
> > Sent: Wednesday, March 9, 2016 8:50:23 AM
> > Subject: Re: Internet Exchanges supporting jumbo frames?
> >
> > 2016-03-09 11:45 GMT-03:00 Nick Hilliard <nick () foobar org>:
> >
> > > this has been tried before at many ixps. No matter how good an idea it
> > > sounds like, most organisations are welded hard to the idea of a 1500
> > > byte mtu. Even for those who use larger MTUs on their networks, you're
> > > likely to find that there is no agreement on the mtu that should be
> > > used. Some will want 9000, some 9200, others 4470 and some people
> > > will complain that they have some old device somewhere that doesn't
> > > support anything more than 1522, and could everyone kindly agree to that
> > > instead.
> >
> >
> >
> > Hi Nick,
> >
> >
> > Thank you for replying so quickly. I don't see why the consensus for an MTU
> > must be reached. IPv6 Path MTU Discovery would handle it by itself,
> > wouldn't it? If one participant supports 9k and another 4k, the traffic
> > between them would be at 4k with no manual intervention. If to participants
> > adopts 9k, hooray, it will be 9k thanks do PMTUD.
> >
> > Am I missing something?
> >
> >
> > Best regards,
> >
> >
> > Kurt Kraut