Internet Exchanges supporting jumbo frames?

Nick Hilliard nick at
Wed Mar 9 19:46:54 UTC 2016

Saku Ytti wrote:
> If customer does not react, put it on quarantine VLAN. This can be
> automated too. Wrong MTU => open internal case, contact customers
> email, no customer response in N days, quarantine VLAN.

... and then the customer will leave the service down because it the
primary peering lan works fine and they couldn't be bothered fixing
jumbo lan connectivity because the neteng who wanted the 9000 byte mtu
connectivity in the first place got distracted by a squirrel or left the
company or was too busy doing other things.

> work, but it's very difficult to actually know without trying what
> works and what does.

I've spent a good deal of time and effort trying to get a jumbo peering
vlan to work and it didn't work for the reasons that I've mentioned, and

For example, many types of hardware don't allow you to specify a
different MTU for different .1q tags on the same physical interface.
This means that if you want a connection to a jumbo MTU vlan and a
standard mtu vlan, you needed two separate connections into the IXP.  At
that point, the ixp participant is unlikely to want to bother because
there's no cost:value justification in getting the second connection.

Don't get me wrong: jumbo MTU IXPs are a great idea in theory.  In
practice, they cause an inordinate amount of pain.


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