Re: [OSPF] AD review of draft-ietf-ospf-rfc4970bis-02

"Acee Lindem (acee)" <> Wed, 23 September 2015 14:37 UTC

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From: "Acee Lindem (acee)" <>
To: Alia Atlas <>, OSPF List <>, "" <>
Thread-Topic: AD review of draft-ietf-ospf-rfc4970bis-02
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Subject: Re: [OSPF] AD review of draft-ietf-ospf-rfc4970bis-02
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Hi Alia,

From: Alia Atlas <<>>
Date: Tuesday, September 22, 2015 at 6:00 PM
To: OSPF WG List <<>>, "<>" <<>>
Subject: AD review of draft-ietf-ospf-rfc4970bis-02

As is customary, I have done my AD review of draft-ietf-ospf-rfc4970bis-02.  First, let me thank Acee for his work on this draft.

I have two major concerns before asking for an IETF Last Call.  I would like to have them
resolved by this Thursday so that the draft can make the Oct 15 IESG telechat.

First, from a process concern, I do not see any active discussion on the OSPF mailing list - even to simply say "yes - go forward".  I don't see anything about this draft or discussion in minutes for IETF 92 or IETF 93.   I'd prefer some indication besides silence and lack of opposition.  I do realize that there are some process or protocol-tidying drafts where there isn't
much interest.  However, I am particularly concerned because this is changing RFC4970 is a way that should be backwards compatible but might trigger issues.   I would encourage WG participants to PLEASE RESPOND!

Second, I can see the intent that by creating an Opaque ID and creating a special meaning for 0, the draft is making efforts to preserve backwards compatibility.  Please add a paragraph or subsection that articulates how and why backwards compatibility isn't an issue.

I will add more on this.

  For extra credit, what happens if the same TLV information is advertised in multiple RI LSAs (as part of moving it from one RI LSA to another)?

This depends on the context of the TLV. In some cases the router information is additive and in others conflicts need to be resolved.

Are there any implementations of this draft?  Has backwards compatibility been verified at all?

Many implementations of RFC 4970. I don’t know of any implementations that originate multiple RI LSAs. However, with all the proposed OSPF RI LSA usages, I can see them coming.

My minor issue is around the IANA considerations; I have detailed comments below.

Here are additional comments.

1) In Sec 2: "The first Opaque ID, i.e., 0, should always contain the Router
   Informational Capabilities TLV and, if advertised, the Router
   Functional Capabilities TLV."  and Sec 2.2 "The first instance ID, i.e., 0,
   should always contain the Router Informational Capabilities TLV and,
   if advertised, the Router Functional Capabilities TLV."

   Since I assume this is important for backwards compatibility, should those
   be SHOULD instead of should?


2) In Sec 2.3: "The first defined TLV in the body of an RI LSA is the Router
   Informational Capabilities TLV."

   Surely that is only for the first Opaque ID=0?  Does each subsequent RI LSA
   also need to contain a Router Informational Capabilities TLV??

No. Will clarify this.

3) In Sec 4 IANA Considerations:  This section is defining the different IANA policies;
when RFC4970 was written, RFC5226 didn't exist.  But since you're doing a bis,
perhaps you can align to the policies in RFC5226 and remove the unnecessary text??

Yes. I think of already done this.

4) In Sec 4 IANA Considerations:  The registry for OSPFv3 LSA Function Codes can
be found at and what is in the draft doesn't match up.  I'd settle for defining the ranges, and value 12 - but it's up to you and IANA on the preferences.  Would it make sense to change the policy from Standards Action to IETF Review here also?

Yes - I think this draft should change the policy for OSPFv3 LSA Functions codes since RFC 4970 initially created the registry. If were going to change the policy (and I think we want to do this), it makes sense to do it here from a continuity standpoint.

Same thing applies to the OSPF RI TLVS ( )   Also here, I think there
was agreement among the 4 of us who commented on the WG mailing list to change this
from Standards Action to IETF Review.


5) In Sec 4 IANA Considerations: "All Router Functional Capability TLV
       additions are to be assigned through standards action."   Given the discussion
about IETF Review vs. Standards Action for other registries, are you sure you want
Standards Action?

No  - I will change this.

I'm sure that we'll get this moving along quickly.

Great - will work on this today in preparation for the tomorrow’s telechat.


Thanks again!