Gorry Fairhurst wrote:
Stig Venaas wrote:
I think this is a good idea, just some minor comments.
The draft says that the checksum will usually be constant for a UDP
flow. This is nice. For some tunnels it can even be computed at
configuration time (when the end-points are determined). I guess
the main case where this isn't the case, is when some datagrams
are fragmented but not all).
I think I agree. IPv6 fragmentation results in some unwanted issues.
draft-eubanks-chimento-6man-00 notes:
The tunneling protocol and implementation must not use
fragmentation of the inner packets being carried.
So, in the current version of UDPTT (-01) it says:
The tunneling protocol and implementation MUST NOT be used to
transport IPv4 or IPv6 packets that use network-layer
fragmentation.
But you are then talking about the packets being transported
(encapsulated inside UDPTT) not being fragments, right?
I believe the UDPTT checksum may depend on whether the UDPTT datagrams
get fragmented after encapsulation.
Anyway, not a big deal, and I agree that all fragmentation is evil :)
Stig
Regarding middleboxes. It says:
o Middleboxes SHOULD NOT truncate IPv6 datagrams where the IP length
exceeds the Length specified in the UDP Header.
I guess some middleboxes might currently also just discard them? Or
maybe discarding is a kind of truncation :) I also wonder whether it
would be better to say MUST? At least they cannot support UDPTT unless
it is a MUST. Or at least a MUST when the length is 8.
OK, this may also be good advice for the next revision.
Stig
Gorry
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