Subject: Sender TSpec on PathTear

From: Adrian Farrel <[email-masked]>
Date: Mon, 20 Mar 2000 12:32:03 -0000

All,

RFC 2205 states that Sender TSpec is mandatory on a PathTear
if a Sender Descriptor is included.

    <PathTear Message> ::= <Common Header> [ <INTEGRITY> ]
                           <SESSION> <RSVP_HOP>
                           [ <sender descriptor> ]

    <sender descriptor> ::= (see earlier definition)

Where the earlier definition of sender Descriptor is found in
the definition of Path Message and is...

    <sender descriptor> ::= <SENDER_TEMPLATE> <SENDER_TSPEC>
                            [ <ADSPEC> ]

draft-ietf-mpls-rsvp-lsp-tunnel-05 does not make any change to 
this requirement, but does add [RECORD_ROUTE] as an optional
field in Sender Descriptor.

It seems to me that SENDER_TSPEC, ADSPEC and RECORD_ROUTE do
not add anything to PathTear.

Can anyone comment on whether or not it would be better to 
define PathTear as

    <PathTear Message> ::= <Common Header> [ <INTEGRITY> ]
                           <SESSION> <RSVP_HOP>
                           [<SENDER_TEMPLATE>]

Of course the effect of this can be mitigated by applying the
usual rules of conservative on send, liberal on receive.

Regards,
Adrian
--
Adrian Farrel  mailto:[email-masked]
Network Convergence Group
Data Connection Ltd., Chester, UK
http://www.datcon.co.uk/
Tel: +44 (0) 1244 313440  Fax: +44 (0) 1244 312422

---

From: Bob Braden <[email-masked]>
Date: Tue, 21 Mar 2000 00:52:07 GMT

*> From [email-masked] Mon Mar 20 04:45:27 2000
  *> From: Adrian Farrel <[email-masked]>
  *> To: [email-masked], [email-masked]
  *> Subject: Sender TSpec on PathTear
  *> Date: Mon, 20 Mar 2000 12:32:03 -0000
  *> MIME-Version: 1.0
  *> X-Mailer: Internet Mail Service (5.5.2650.21)
  *> Sender: [email-masked]
  *> Precedence: bulk
  *> X-Lines: 44
  *> 
  *> All,
  *> 
  *> RFC 2205 states that Sender TSpec is mandatory on a PathTear
  *> if a Sender Descriptor is included.
  *> 
  *>     <PathTear Message> ::= <Common Header> [ <INTEGRITY> ]
  *>                            <SESSION> <RSVP_HOP>
  *>                            [ <sender descriptor> ]
  *> 
  *>     <sender descriptor> ::= (see earlier definition)
  *> 

And the very next sentence says, "A PathTear message may include a
SENDER_TSPEC or ADSPEC object in its sender descriptor, but these
must be ignored".

There are several places where the text modulates the BNF, and
this is one of them.  This presentation was chosen for simplicity
and (we thought) clarity, but apparently it failed for you.

Bob Braden