See inline... Tom P. > -----Original Message----- > From: dccp-bounces@xxxxxxxx [mailto:dccp-bounces@xxxxxxxx] On Behalf Of > Colin Perkins > Sent: Thursday, February 21, 2008 4:16 PM > To: Dan Wing > Cc: ''dccp' working group'; Phelan, Tom > Subject: Re: DCCP-over-UDP [was draft-phelan-dccp-natencap-00.txt] > > On 21 Feb 2008, at 18:25, Dan Wing wrote: > >> On 19 Feb 2008, at 18:43, Dan Wing wrote: > >> ... > >>> DCCP has an initiation handshake. It seems effective, to me, > >>> to define SRV records that are something like this: > >>> > >>> _foobar._dccp SRV 0 0 1234 server.example.com. > >>> _foobar._dccp-udp SRV 0 0 1234 server.example.com. > >>> > >>> and protocol foobar then tries both a native DCCP handshake > >>> (to DCCP port 1234) and a DCCP-over-UDP handshake (to UDP > >>> port 1234). We could do the native DCCP first and try > >>> DCCP-over-UDP 100ms (or whatever you like) later. > >>> > >>> This provides the incremental deployment we need (with > >>> dccp-udp) and provides an easy path to real DCCP deployment > >>> (where the UDP encapsulation is not necessary because there > >>> are no meddling on-path IPv4 NATs). > >>> > >>> Would this be feasible? > >> > >> Sure, but is it needed? If you want DCCP-over-UDP encapsulation to > >> be seamless, then surely you need to try it every time a native > >> connection attempt fails. In that case, there's no need for > >> separate signalling. > > > > What do you mean by 'separate signaling' -- are you referring to > > the SRV record with _dccp-udp? > > Yes. > > > I worry that the DCCP-UDP port might need to be different than the > > DCCP-RAW port. Are you expecting them to always be the same? That > > should be a reasonable assumption most of the time, but I worry it > > might not work in some case. > > I am expecting them to always be the same. My model is that a each > instance of the DCCP transport can either send packets natively over > IP, or tunnelled over UDP. Since it's a single transport instance, > the same port space would be used for encodings of the data. > [Tom P.] As I said in another e-mail, if you make the UDP port equivalent to the DCCP port, that means you can't have UDP apps. I don't think that's a workable solution. > -- > Colin Perkins > http://csperkins.org/ >
