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

[<[e-mail]>]

Bert,

Many thanks for your comments.
More inlined.

Bruno

> -----Message d'origine-----
> De : Bert Wijnen - IETF [mailto:[e-mail]]
> Envoyé : dimanche 27 avril 2008 11:43
> À : [e-mail]; [e-mail]; 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:[e-mail]]
> Verzonden: donderdag 24 april 2008 13:55
> Aan: [e-mail]
> 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	However, the specific prefixes in the IGP area should only be withdrawn (by the ABRs) once all the LSR of this IGP area have been upgraded.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:[e-mail]]
> 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
> ([e-mail]), preferably before next Wednesday if possible.
> 
> Thank you Bert,
> 
> Ted
> 
> 
> 

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