IMHO, what should drive the use or no use of UDP is "the need and use of UDP functons", rather then "the need to make the SCTP and SCCP more popular because of using a popular transport". Perhaps I am not reading right the motivation, but I somehow get that frm the thread - sorry... Which is to say that I agree with Fred's concern 100% about duplications of functions. I would perhaps even go a little further, if the counter-argument is that with "UDP lite", there is a minimization of duplication, and that is: my concern would be that besides the dupplication, there is some additional burden in processing a packet that has mutliple header layers, when passing the packet from one layer to the other. It's not much, but there is, and can add-up - there are the little things that, when in larhe numbers, contribute to a considerable load. If that can be eliminated, I see it as a plus... Alex Conta > -----Original Message----- > From: tsv-area-bounces@xxxxxxxx > [mailto:tsv-area-bounces@xxxxxxxx] On Behalf Of L.Wood@xxxxxxxxxxxx > Sent: Tuesday, April 27, 2010 6:38 AM > To: fred@xxxxxxxxx > Cc: dccp@xxxxxxxx; tsv-area@xxxxxxxx; tsvwg@xxxxxxxx > Subject: RE: UDP encaps for SCTP and SCCP > > > 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
