Iljitsch,
At 05:57 PM 07/22/2005, Iljitsch van Beijnum wrote:
On 22-jul-2005, at 22:18, Bob Hinden wrote:
In my personal view, having devices on shared media with different
MTU's is just a bad idea. Trying to get it to work is complicated
and I think it will have lots of nasty failure cases. If one wants
to have mixed speeds (like the example above) then use the default
MTU (i.e., 1500) or replace the GbE-Switch with a Router. If one
wants Jumbo Frames, then make sure all of the nodes on the link
support 1000Base-T.
Unfortunately 1000baseT (is that the correct designation?) doesn't
equal jumboframe capability, so the problem remains.
Right, I don't know what the correct designation is either.
Don't forget that management issues in layer 2 networks (= a single
layer 3 subnet) are very different from those on the global internet:
most layer 2 networks are managed by a single organization. Since we
had the hubris to think we could do PMTUD for the global internet, I
think we shouldn't shy away from doing the same thing for layer 2. As
always, the operator community will decide wheter what we come up
with is usable in practice.
Fair point. As suggested on the list a new NA/NS option seems like a
reasonable approach except for the problems pointed out. Having to do
probes of different packet sizes is fairly messy if there is a device in
the middle with a smaller MTU. Would a NA/NS option solution solve enough
of the problem to make doing it worthwhile?
Bob
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