Internet Exchanges supporting jumbo frames?

Kurt Kraut listas at
Wed Mar 9 23:58:08 UTC 2016

Hello folks,

First of all, thank you all for this amazing debate. So many important
ideas were exposed here and I wish we keep going on this. I've seen many
opposition to my proposal but I still remain on the side of jumbo frame
adoption for IXP. 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.

One of the reasons I'm so surprised with concerns about compatibility and
breaking the internet I've seen here is the offers I get from my IP transit
providers: half of them offered me jumbo frame capable ports by default, it
wasn't a request. When this subject became important to me and I open
support tickets, half of them replied something like 'You don't need to
request it. From our end the max MTU is X'. The lowest X I got was 4400 and
the highest 9260 bytes. All my Tier-1 providers already provided me jumbo
frames IP transit. Even my south american IP Transit provider activated my
link with 9k MTU by default.

So we have Tier-1 backbones moving jumbo frames around continents, why in a
controlled L2 enviroment that usually resides in a single building and
managed by a single controller having jumbo frames is that concerning?

Best regards,

Kurt Kraut

2016-03-09 19:22 GMT-03:00 Tassos Chatzithomaoglou <achatz at>:

> I must be missing something very obvious here, because i cannot think of
> any reason why an IXP shouldn't enable the maximum possible MTU on its
> infrastructure to be available to its customers. Then it's clearly
> customers' decision on what MTU to use on their devices, as long as:
>   * It fits inside IXP's MTU
>   * It suits with any other customer's (exchanging traffic with) MTU
> --
> Tassos
> Kurt Kraut via NANOG wrote on 9/3/16 16:26:
> > Hi,
> >
> >
> > I'm trying to convince my local Internet Exchange location (and it is not
> > small, exceed 1 terabit per second on a daily basis) to adopt jumbo
> frames.
> > For IPv6 is is hassle free, Path MTU Discovery arranges the max MTU per
> > connection/destination.
> >
> > For IPv4, it requires more planning. For instance, two datacenters tend
> to
> > exchange relevant traffic because customers  with disaster recovery in
> mind
> > (saving the same content in two different datacenters, two different
> > suppliers). In most cases, these datacenters are quite far from each
> other,
> > even in different countries. In this context, jumbo frames would allow
> max
> > speed even the latency is from a tipical international link.
> >
> > Could anyone share with me Internet Exchanges you know that allow jumbo
> > frames (like does) and how you notice
> benefit
> > from it?
> >
> >
> > Best regards,
> >
> >
> > Kurt Kraut
> >

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