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RE: OPS-DIR review for: draft-ietf-mpls-ldp-interarea-03.txt

2008-04-28 08:13:35
Bert,

Many thanks for your comments.
More inlined.

Bruno

-----Message d'origine-----
De : Bert Wijnen - IETF [mailto:bertietf(_at_)bwijnen(_dot_)net]
Envoyé : dimanche 27 avril 2008 11:43
À : ietf(_at_)ietf(_dot_)org; ina(_at_)juniper(_dot_)net; LE ROUX Jean-Louis 
RD-SIRP-LAN; DECRAENE Bruno RD-CORE-ISS
Objet : FW: OPS-DIR review for: draft-ietf-mpls-ldp-interarea-03.txt

Forwarding to IETF wide list and authors/editors

Bert Wijnen

-----Oorspronkelijk bericht-----
Van: Bert Wijnen - IETF [mailto:bertietf(_at_)bwijnen(_dot_)net]
Verzonden: donderdag 24 april 2008 13:55
Aan: ops-dir(_at_)ietf(_dot_)org
Onderwerp: OPS-DIR review for: draft-ietf-mpls-ldp-interarea-03.txt


I reveied this document for the OPS Directorate

In general, I think the document is ready for publication.

In sect 7.1 I read:

   For the successful establishment of end-to-end MPLS LSPs whose FEC
   are aggregated in the RIB, this specification must be implemented on
   all LSRs in all areas where IP aggregation is used. If an LSR on the
   path does not support this procedure, then the LSP initiated on the
   egress LSR stops at this non compliant LSR. There are no other
   adverse effects.

I think/hope (but it would be good to see this confirmed) that this does
not mean that all LSRs in the set of IGPs that are involved need to be
upgraded with the new protocol at exactly the same time.

The way I understand it, one can upgrade the LSRs at different times,
but should only activate this new mechnaism once all LSRs have
ineeded been upgraded with the new capability.

You're right: all LSRs do not need to be upgraded at the same time:
- deployment in each IGP (area) is independent
- LSRs can be upgraded at any time in any order,
- This new mechanism can be activated on the LSR at any time in any order, 
(upgrade and activation can be done at same step if it's considered easier)
- Then, if the FEC/LSP were used, we need a non disruptive deployment:
        (As a reminder, the ABRs used to leak all specific prefixes in the IGP 
area.)
        The ABRs can advertise the (new) aggregate prefix at any time and any 
order.
        However, the specific prefixes in the IGP area should only be withdrawn 
(by the ABRs) once all the LSR of this IGP area have been upgraded. (Otherwise 
"If an LSR on the path does not support this procedure, then the LSP initiated 
on the egress LSR stops at this non compliant LSR.")

Do you think this should be clarified in the document?

 
Nits:

Thanks.
All corrections are done and will appear in the next revision.

 
- There are several/many acronyms in this document that never get
  expanded. It is good pratice to always expand an acronym when
  it is used for the first time.

- Abstract

   To facilitate the establishment of Label Switched Paths (LSP) that
   would span multiple IGP areas in a given Autonomous System (AS), this
   document proposes a new optional label mapping procedure for the
   Label Distribution Protocol (LDP).

  s/proposes/describes/ (at least once this comes out as RFC, right?)

- need to add citation to RFC2119 in section 1.
  And add a normative reference for RFC2119.

- 2nd para section 4:

   To set up the required MPLS LSPs between PEs in different IGP areas,
   services providers have currently three solutions: LDP with IGP route

  s/services/service/ I think.

- consistency: I see
    Service providers
    service providers
    Service Providers
  I suggest to use consistent capitalization

- 1st para sect 5:

   This document defines a new label mapping procedure for [LDP]. It is
   applicable to IPv4 and IPv6 prefix FEC elements (addresses families 1
   and 2 as per [ASSIGNED_AF]). It MUST be possible to activate / ^M

  I believe it is "address families" (or maybe "addressing families") but
  not "addresses families". So I would: s/addresses/address/

- sect 5, I see
     longest match label mapping procedure
     longest match Label Mapping Procedure
     "Longest Match" label mapping procedure
     longest match procedure
  you might want to be a bit moire consistent

- Section 5:

     - next-hop change when an existing prefix have new next hop
        following a routing change.

   s/have new/has a new/ ??

     - When the next-hop of a RIB prefix change, the LSR must change

   change the first "change": s/change/changes/ or so I think.

- 2nd para section 7.2

   In case of failure of the egress LER node, given that the IGP
   aggregates IP route on ABRs, the routing convergence behavior is
   changed compared to [LDP]. As the IGP does not carry specifics
   prefixes outside of the egress area, the IGP will not propagate the

  s/specifics prefices/specific prefixes/ (or so I think)

- Last para sect 7.2
   For all others failures

  s/others/other/
Bert Wijnen

-----Oorspronkelijk bericht-----
Van: Seely, Ted A [CTO] [mailto:Ted(_dot_)A(_dot_)Seely(_at_)sprint(_dot_)com]
Verzonden: donderdag 17 april 2008 13:42
Aan: Bert Wijnen
Onderwerp: OPS DIR Review Request


Hello Bert,

As a member of the Operations Directorate you are being asked to review the
following IESG work item for it¹s operational impact.

IETF Last Call:

http://www.ietf.org/internet-drafts/draft-ietf-mpls-ldp-interarea-03.txt
BTW - This is a very short draft.

If possible please provide comments and review to the Ops-dir mailing list
(ops-dir(_at_)ietf(_dot_)org), preferably before next Wednesday if possible.

Thank you Bert,

Ted




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