PTP GM and OC are allowed to set the UDP checksum to 0 (according to the standard - UDP/IPv4 encap). In such case no action on the updating the UDP checksum would be required by the TCs. The TC itself can also set the UDP checksum to 0 (according to the standard any intermediate node can do so).
This would also apply to the case where you have TCs interconnected by two BCs. - Michel -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Stewart Bryant Sent: January 21, 2011 03:27 PM To: [email protected] Subject: Re: [TICTOC] UDP checksum Presumably this is a v6 discussion. I can't see any point in using the c/s in v4. WRT v6 there is a movement to make this optional (the debate is happening in 6lowlan, and I think that we should be pushing to turn it off for PTP. The worst that can happen is that we receive a corrupt pkt and either junk it, or put it in the timing servo whereupon it gets rejected as an outlier. - Stewart On 20/01/2011 23:52, Shahram Davari wrote: > Hi Manav, > > The minimum requirement is to do UDP checksum incremental update on > transmission. If full update is done then UDP checksum must be verified on > reception as well. > > Thx > Shahram > > -----Original Message----- > From: Bhatia, Manav (Manav) [mailto:[email protected]] > Sent: Thursday, January 20, 2011 3:33 PM > To: Shahram Davari; [email protected] > Subject: RE: UDP checksum > > Hi Shahram, > > It may be ok as long as the HWs are incrementally recalculating it. However, > if its being done afresh then we have an issue. I don't see how the HW > behavior can be mandated in a spec. > > Cheers, Manav > >> -----Original Message----- >> From: Shahram Davari [mailto:[email protected]] >> Sent: Friday, January 21, 2011 4.59 AM >> To: Bhatia, Manav (Manav); [email protected] >> Subject: RE: UDP checksum >> >> Hi Manav, >> >> UDP checksum is usually not verified before updating the CF. >> After CF update it is incrementally recalculated. The end >> host will then verify the checksum for correctness. >> >> Regards, >> Shahram >> >> -----Original Message----- >> From: [email protected] >> [mailto:[email protected]] On Behalf Of Bhatia, Manav (Manav) >> Sent: Thursday, January 20, 2011 3:16 PM >> To: [email protected] >> Subject: [TICTOC] UDP checksum >> >> Hi, >> >> Are the LSRs acting as TCs expected to verify the checksum >> before they update the correction field? If no, then there is >> no point in these LSRs in updating the UDP checksum as they >> will "correct" the checksum when its recomputed after >> modifying the CF field. In this case wouldn't it make more >> sense to just update the checksum at the MPLS terminating point? >> >> I also think that updating the UDP checksum may be redundant >> as the LSRs are anyways verifying the outer ethernet checksum >> before accepting any packets. Any thoughts here? >> >> Cheers, Manav >> >> -- >> Manav Bhatia, >> IP Division, Alcatel-Lucent, >> Bangalore - India >> >> >> _______________________________________________ >> TICTOC mailing list >> [email protected] >> https://www.ietf.org/mailman/listinfo/tictoc >> >> >> > _______________________________________________ > TICTOC mailing list > [email protected] > https://www.ietf.org/mailman/listinfo/tictoc > -- For corporate legal information go to: http://www.cisco.com/web/about/doing_business/legal/cri/index.html _______________________________________________ TICTOC mailing list [email protected] https://www.ietf.org/mailman/listinfo/tictoc _______________________________________________ TICTOC mailing list [email protected] https://www.ietf.org/mailman/listinfo/tictoc
