Subject: Conflicting scenarios in 2205 and 2209

From: Apratim Mukherjee <[email-masked]>
Date: Tue, 8 May 2001 15:32:41 +0530

Hi,

RFC2205 says:
"A unicast PathTear must not be forwarded if there is path state for the
same (session, sender) pair but a different PHOP" page 41.
This appears correct and should be the case if the PathTear was initiated
due to a route change downstream which will ultimately converge onto the
previous path at some node upstream.
However , RFC 2209 does not address this problem.
1. There is no mention in the message processing rules for the PathTear
message .
2. a)While accepting Path Message , we search for a matching path state
using only (Session,Sender Template) as index and later update the Path
State if the PHOP has changed .
   b) Instead , should not a separate Path State be created for a Path
Message with matching Session and Sender Template but differing PHOP ?
(Otherwise the RFC 2205 mention will not make sense as two path states with
different PHOPs will never exist ).
   If this were true , then all Path State search should be done based on
(Session,Sender Template, PHOP )indexing unlike (Session,Sender
Template)indexing as is the case now . 
(Adding to my confusion is the fact that that the implementation also uses
this method of indexing )

Does 2a) imply the statement in RFC 2205 ?
Or is 2b) the correct approach ?
Should a step be added to the Message Processing Rules of a Path Tear
Message to reflect the statement in RFC 2205 ?

Thanks
Apratim

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From: Bob Braden <[email-masked]>
Date: Tue, 8 May 2001 15:29:32 GMT

I don't have time now to figure out the answer to your question,
but RFC2209 is known to have problems, while we are not aware of
errors in RFC 2205 at this point.  [Left to my own devices, I
would not have published RFC 2209 as it was, but the RSVP WG
made the decision.]

Bob Braden