North American Network Operators Group
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Re: Thoughts on increasing MTUs on the internet

  • From: Saku Ytti
  • Date: Thu Apr 12 07:54:31 2007 
On (2007-04-12 11:20 +0200), Iljitsch van Beijnum wrote:
 
> What do you guys think about a mechanism that allows hosts and  
> routers on a subnet to automatically discover the MTU they can use  
> towards other systems on the same subnet, so that:
> 1. It's no longer necessary to limit the subnet MTU to that of the  
> least capable system
> 
> 2. It's no longer necessary to manage 1500 byte+ MTUs manually

To me this sounds adding complexity for rather small pay-off. And
then we'd have to ask IXP people, would the enable this feature
if it was available? If so, why don't they offer high MTU VLAN
today?
And in the end, pay-off of larger MTU is quite small, perhaps
some interrupts are saved but not sure how relevant that is
in poll() based NIC drivers. Of course bigger pay-off
would be that users could use tunneling and still offer 1500
to LAN.

IXP peeps, why are you not offering high MTU VLAN option?
>From my point of view, this is biggest reason why we today
generally don't have higher end-to-end MTU.
I know that some IXPs do, eg. NetNOD but generally it's
not offered even though many users would opt to use it.

Thanks,
-- 
  ++ytti