On Jun 3, 2010, at 10:44 PM, Carsten Bormann wrote:
On Jun 4, 2010, at 06:30, Jonathan Hui wrote:
I personally think it would not be a major disaster to increase the
MTU requirement for 6LRs beyond RFC 4944's 1280, as long as hosts
can stay at 1280.
(If this is what ROLL decides should be done, let's have a separate
discussion on any implications in 6lowpan.)
Since we're on this subject, how does this relate to the requirement
in RFC 2460 that all nodes must be able to receive datagrams of up to
1500 bytes (after reassembly if IP-layer fragmentation is used)? What
is the value of keeping the MTU requirement at 1280 for hosts if they
are still required to receive a 1500 byte datagram? Or is is that we
have relaxed the 1500 byte requirement for hosts in a 6lowpan network?
If a 6lowpan host needs to receive a 1500 byte datagram, I'd prefer to
let the 6lowpan layer handle the fragmentation needs rather than both
link and IP-layer fragmentation working simultaneously to deliver a
1500 byte datagram.
If a 6lowpan host only needs to receive a 1280 byte datagram, then I
agree that keeping the 1280 byte MTU for 6lowpan hosts is useful.
--
Jonathan Hui
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