regards, Jukka
On 12.4.2010 23:17, Phelan, Tom wrote:
Hi Jukka, Well, I guess one of us misunderstands something, because it looks to me like GUT doesn't work. Taking your example in section 3.3 of the draft: We start out with a DCCP packet encapsulated in IP as: Dest addr (DA): B Src addr (SA): A DCCP Ports : E and F (I assume that's what your notation means) DCCP checksum calculated over contents of DCCP packet and IP pseudo header with DA/SA = B/A This packet gets GUT'd as: DA: B SA: A UDP Ports: E and GUT DCCP packet unchanged This packet gets NAT'd as: DA: B SA: C UDP Ports: P and GUT DCCP Packet unchanged This packet arrives at the remote host and gets un-GUT'd as: DA: B SA: C (!) DCCP packet unchanged And this packet fails DCCP checksum because the Source Address (C) is different now than when the checksum was calculated initially (with SA = A). What am I missing? Tom P.-----Original Message----- From: Jukka Manner [mailto:jukka.man...@tkk.fi] Sent: Monday, April 12, 2010 3:21 PM To: Phelan, Tom Cc: Colin Perkins; DCCP working group Subject: Re: [dccp] I-D Action:draft-ietf-dccp-udpencap-00.txt DCCP wouldn't need to care about checksums if we had a generic encapsulation scheme, such as the one we have been discussing on theTSVlist, the Generic UDP Tunneling scheme GUT. Jukka On 04/12/2010 06:05 PM, Phelan, Tom wrote:Hi All, OK, I'll accept the apparent consensus and make the DCCP header thesameformat in both encapsulations. Note that a DCCP implementation isstillgoing to need to know whether this came in with UDP encap or STDencap-- the checksum processing needs to be different at least. Tom P.-----Original Message----- From: Colin Perkins [mailto:c...@csperkins.org] Sent: Sunday, April 11, 2010 5:55 AM To: Phelan, Tom Cc: Pasi Sarolahti; DCCP working group Subject: Re: [dccp] I-D Action:draft-ietf-dccp-udpencap-00.txt On 7 Apr 2010, at 15:14, Phelan, Tom wrote:-----Original Message----- From: Pasi Sarolahti [mailto:pasi.sarola...@iki.fi] Sent: Thursday, February 18, 2010 5:54 PM To: DCCP working group Cc: Phelan, Tom Subject: Fwd: [dccp] I-D Action:draft-ietf-dccp-udpencap-00.txt...* worth considering a straight UDP encapsulation that does notadjustthe position and order of the fields. -- Gorry / 2009-11-20[Tom P.] Worth considering, but since there are already two implementations of the existing encapsulation I'm going to resist this.We're early enough in the life of DCCP that I'd prefer we get this right, than preserve running code that has minimal deployment. -- Colin Perkins http://csperkins.org/-- Jukka MJ Manner, Professor, PhD. Phone: +358+(0)9+470 22481 Aalto University Mobile: +358+(0)50+5112973 Department of Communications Fax: +358+(0)9+470 22474 and Networking (Comnet) Office: G320a (Otakaari 5A) P.O. Box 13000, FIN-00076 Aalto E-mail: jukka.man...@tkk.fi Finland www.netlab.hut.fi/~jmanner/
<<attachment: jukka_manner.vcf>>