Re: I-D ACTION:draft-rahman-rtg-router-alert-dangerous-00.txt
Magnus Westerlund <[email protected]>
| Newsgroups | gmane.ietf.nsis,gmane.ietf.tsvwg |
|---|---|
| Message-ID | <[email protected]> |
David Ward skrev: > Roland - > > On Oct 21, 2008, at 3:35 AM, Roland Bless wrote: > >> Hi Magnus, >> >> Magnus Westerlund wrote: >>> I reacted on the following sentence from Section 4: >>> >>> A router SHOULD inspect Router Alert packets before sending them to >>> the "slow path" so that if the protocol to which a packet belongs is >>> not enabled on the router or on the incoming interface (physical or >>> virtual), then the packet is dropped. >>> >>> Isn't this preventing use of RAO completely unless all nodes between >>> source and destination supports RAO and that protocol? Isn't the right >>> answer to not kick it into the slow path and simply forward it? >> >> Yes, the behavior should be: simply forward the packet in case >> the router does not understand/intercept packets with this RAO value. >> Otherwise an efficient interception as we need it in NSIS is >> not possible. >> If the router is the destination of the packet and it doesn't >> understand the RAO, it probably could drop the packet. >> > > DW: The RSVP spec doesn't state this clearly thus the confusion. Why are we talking about RSVP here? RAO for IPv4 is RFC 2113 which says: 2.2 Semantics Hosts shall ignore this option. Routers that do not recognize this option shall ignore it. Routers that recognize this option shall examine packets carrying it more closely (check the IP Protocol field, for example) to determine whether or not further processing is necessary. Unrecognized value fields shall be silently ignored. The semantics of other values in the Value field are for further study. Maybe not 100% clear in regards to the value and that the packet simply should be forward for unrecognized value. But I think it is reasonable that your document helps clarify this. Cheers Magnus Westerlund IETF Transport Area Director & TSVWG Chair ---------------------------------------------------------------------- Multimedia Technologies, Ericsson Research EAB/TVM ---------------------------------------------------------------------- Ericsson AB | Phone +46 8 4048287 Färögatan 6 | Fax +46 8 7575550 S-164 80 Stockholm, Sweden | mailto: [email protected] ----------------------------------------------------------------------