Niels Bakker wrote:
* sam_mailingli...@spacething.org (Sam Stickland) [Tue 03 Feb 2009,
13:04 CET]:
For what it's worth, TCP will negiogate MSS and will work with
mismatched MTU in a single LAN segment.
No
Machine 1 -- switch with 1500 byte MTU -- switch with smaller MTU --
switch with 1500 byte MTU -- machine 2
Same situation as when you have IP routers with smaller MTUs in the
path that also do not send ICMP Fragmentation Needed errors (or those
are dropped on the way to you)
If you configure one of those machines with an MTU equal to or smaller
than the smallest MTU in the path then yes TCP (assuming MSS option is
used) won't send packets that happen to be too big, but again, same
story as for routers vs on a LAN. The problem isn't that machine 1
and 2 in the above example disagree on MTU, the problem is that
equipment in the path disagrees on the MTU and cannot (in the case of
switches) send notifications of such, or those will not arrive (in the
case of stupid firewall admins in control of networks).
Sorry, I should had clarified. I meant mismatched host MTUs within a
jumbo MTU supporting L2 domain.
Sam
