Hi Tony, Tony Li wrote: > I've got an architectural issue with any protocol having specific values > in the RAO. In general, that's > a poor approach, as it will (in the long term) lead to multiple > protocols piggybacking on RAO. Why not simply allocate another option > on a per-protocol basis? > > This also has the nice side effect that it ensures that things are > backward compatible.
Thanks for your comments. If you're interested in this topic I'd like to point at Appendix C of the GIST draft that provides more background information: http://tools.ietf.org/html/draft-ietf-nsis-ntlp-14#appendix-C We had already some discussions about this and I'll try to summarize why we choose to use the RAO (maybe other NSIS WG members or Robert can jump in here) approach. It was mainly driven by RSVP experience: 1) better chances of NAT and Firewall traversal, an own protocol number didn't work too well for RSVP (raw IP with protocol #46) 2) RSVP already used the RAO mechanism, thus lets re-use it. The basic concept is: due to path-coupled signaling we want to intercept signaling packets that are sent to the data flow's destination. Each NSIS signaling protocol (e.g, QoS NSLP or NAT/FW NSLP) uses a specific RAO value, so a packet can bypass easily if it carries the "wrong" RAO value. This assumes that an implementation can specifically intercept packets depending on the RAO value and let non-matching packets bypass in the fast path. I don't see the danger that "multiple protocols are piggybacking on RAO", because only protocols will use this mechanism if they need to _intercept_ packets, like GIST does for discovering signaling nodes along a flow's path. I don't understand what you mean by "allocate another option on a per-protocol basis". Do you mean an own protocol number or a new IP option or demultiplexing within the protocol itself (which we also do). Could you explain this a little bit more? Regards, Roland _______________________________________________ Int-area mailing list [email protected] https://www1.ietf.org/mailman/listinfo/int-area
