On Thu, Mar 15, 2007 at 12:44:35PM -0700, Steven Kurylo wrote:
> >> You really need a switch which supports path discovery.
> >
> >In general, I haven't seen or read much discussion on PMTU discovery at the
> >link layer. My gut feel is that it would be something proprietary if it
> >did exist.
>
> When I say a switch, I mean in the generic term. So it would have to
> be layer 3.
>
> >Traditional PMTU works at the network layer (IP) where datagrams cross link
> >boundaries. The RFC that describes doing PMTU discovery basically says try
> >sending smaller datagrams until they start getting through.
>
> Actually, it only tries smaller packets if it receives a fragmentation
> needed ICMP packet back from a router along the path.
Yeah, kind of stupidly phrased on my part, sort of talking about 2 different
things in the same paragraph. The IP stack in the router (layer 3) would
probably not be able to hand it off to the Ethernet layer (an exception/
error) and could take care of it. The Ethernet layer on the router would
have to know it's MTU ahead of time.
Received on Thu Mar 15 14:19:37 2007
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