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Re: [RRG] A data point on transit MTU size
On 22 sep 2008, at 23:49, Brian E Carpenter wrote:
We've argued here about whether it's reasonable to assume >1500 byte
MTU on transit links, when running a LISP-type solution.
Here's a data point about the real world, as far as Internet exchange
points at the southern end go:
Note that they only talk about the capabilities of their switches.
Obviously jumbo capability there is a prerequisite, but this is easily
met by pretty much all gigabit and faster gear. The next problem,
which is harder to crack, is finding a way to send larger packets even
though some routers on the shared infrastructure don't support this.
I've been working for a while now on a draft that would solve this
through automatic discovery and testing of the jumboframe capability
between two systems on a subnet two systems can use the max MTU they
both support between them without being limited by less capable
systems on the same subnet:
However, for the internet exchange case this would probably be much
easier to solve through static configuration. Something like static
ARP entries with an MTU attached that can overrule the default MTU.
Would any of our favorite vendors be interested in implementing
something like that?
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