Fred, advocating removing the interior protocol checksum across header and payload (and reconstituting/recomputing it afterwards) violates end-to-endidness and weakens the reliability guarantee. Bad idea. From a checksum perspective, you'd do better saying 'use UDP lite with a minimal check just across its own headers and pseudo-header' to decrease the computational overhead - that should be a fixed value. Using a UDP (or lite) port to indicate what is being done here with a particular weird encap, as well as the original ports on the interior packet, is something that this approach is stuck with, I think. Lloyd Wood http://sat-net.com/L.Wood ________________________________________ From: Fred Baker [fred@xxxxxxxxx] Sent: 27 April 2010 10:55 To: Lars Eggert Cc: bidulock@xxxxxxxxxxx; dccp@xxxxxxxx; tsv-area@xxxxxxxx; tsvwg list; Wood L Dr (Electronic Eng); Michael Welzl Subject: Re: UDP encaps for SCTP and SCCP >From my perspective, I would prefer to run a native encapsulation rather than host it in UDP. If one wants a UDP encapsulation, I have no opinion on which of the choices to make, but I would suggest a characteristic you want to have. There is no point having UDP ports *and* SCTP/DCCP ports, and no point in having a UDP checksum *and* an SCTP checksum. I would recommend removing the duplicated functions from the interior protocol and relying on UDP's counterpart, even if it is inferior, as it will be more readily deployed. On Apr 27, 2010, at 10:42 AM, Michael Welzl wrote: > Hi, > > Okay, I herewith speak up: yes I want to see UDP encapsulation for both these protocols > (but right now I'm not sure which one). > > Both SCTP and DCCP are useful - if there was no consensus on that, ever, these > groups would never have been formed, and the protocols would never have > been developed. > > Now, they are not used much (on the Internet involving NATs); at least > DCCP isn't. That's a problem. UDP encapsulation is a way to try to > solve this problem - and saying that we shouldn't do this because the > protocols aren't used is a bit stupid, isn't it? > > To repeat this more clearly and bluntly: > > tool X isn't working well => noone uses it. > So let's not fix tool X because noone uses it anyway. > Hmmm... > > Cheers, > Michael > > > On Apr 27, 2010, at 9:47 AM, Lars Eggert wrote: > >> Hi, >> >> please keep this discussion focused on which approach we should follow for UDP-encapsulating DCCP and SCTP. >> >> I'm happy Lloyd posted his views. I'm hoping other community members will speak up as well. If I were asked to characterize current consensus, I'd probably say "disinterest for either approach." (Which would be fine, but doesn't quite match the earlier feeling I got from the community, i.e., that we do want UDP encaps for these protocols.) >> >> Lars > http://www.ipinc.net/IPv4.GIF
