Subject: Comments on draft-ietf-mpls-rsvp-lsp-tunnel-06

From: Adrian Farrel <[email-masked]>
Date: Wed, 26 Jul 2000 20:46:34 +0100

George,

A couple of questions and some minor editorial thoughts.  Sorry if I'm
revisiting old ground - if so please simply reply "see archive".

Hope this is of use.

Regards,
Adrian

Questions
=========

4.4.1.3 Recorded Label Subobject
    I can see how this is useful information for NM.  Is the label
    completely useful without knowing the label space from which the 
    label comes?  This would be exposed as an interface index or a 
    magic value for the global label space.  This could easily be added 
    to the subobject to give...

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     Type      |     Length    |    Flags      |   C-Type      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       Interface Identifier                                    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       Contents of Label Object                                |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

    with the following text

      Interface Identifier

         The interface index that identifies the label space from which
         this label comes.  A value of zero (0) indicates that the label 
         comes from the global label space.

4.4.2 RRO Applicability
    The text inherited from the previous draft says that an RRO can
    be converted to an ERO "with minor changes".  This has now been
    broken by the addition of the Label subobject.
    It would be unfortunate (but perhaps necessary?) to require that
    the RRO is parsed when pinning a session path.  The alternative
    would appear to be to allow the Label object to be present but
    ignored in the ERO.

4.5 Processing RRO
    The text here describes adding the Label Record subobject whenever
    the SESSION_ATTRIBUTE indicate Label_Recording.  Of course, this 
    is typically only possible on the reverse path.  Thus the RRO on 
    he forward path need not include the LR subobject.

4.5 Processing RRO
    Can we allow for nodes that don't support adding Label Record
    subobjects?  Or is this covered in "SHOULD"?

Editorial
=========

2.6 Step 2. If DF bit not set step a)
    Would it be clearer (and no less accurate :-) to replace "the value
    of the parameter" with "M"?

3.2 Expanding <FF flow descriptor list> leads to (optionally) two
    instances of <FLOWSPEC> for a single <FILTER_SPEC> and <LABEL>.
    I'm assuming you didn't want this (or is there a cunning use?)
    and that the correct correlation to adding <FLOWSPEC> to the
    <FF flow descriptor list> is to remove it from the
    <FF flow descriptor>.

4.8.1 Session Attributes - Flags (ditto 4.8.2)
    Is it wise to re-use the "Merging Permitted" flag for "Label 
    recording desired"?  won't this cause interop issues with old
    implementations?
    
Typos
=====

1.2 Definition of Traffic Engineered Tunnel (TE Tunnel)
    For "An set" read "A set"

1.2 Definition of Traffic Trunk
    ditto

2.6 Paragraph 2
    Reference should be to "4.9" not "4.8"

3.2 <FF flow descriptor list>
    This line is too long.

4.1.1.2  Section 2.
    Line is too long.

4.5.2 Penultimate line
    For "to" read "for".

4.8.3 Page 50 second paragraph fourth line
    strike "of the"

6. Security Considerations
    For "which" read "wish".
--
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