Subject: Re: [OSPF] Alvaro Retana's No Objection on draft-ietf-ospf-encapsulation-cap-06: (with COMMENT)

From: <[email-masked]>
Date: Mon, 18 Sep 2017 15:26:54 +0000

Hi Alvaro,

Thanks for your review and feedback.
Please see inline [Bruno]

> From: Alvaro Retana [mailto:[email-masked]]
 > Sent: Wednesday, August 30, 2017 8:41 PM
> 
 > Alvaro Retana has entered the following ballot position for
 > draft-ietf-ospf-encapsulation-cap-06: No Objection
 > 
 > When responding, please keep the subject line intact and reply to all
 > email addresses included in the To and CC lines. (Feel free to cut this
 > introductory paragraph, however.)
 > 
 > 
 > Please refer to https://www.ietf.org/iesg/statement/discuss-criteria.html
 > for more information about IESG DISCUSS and COMMENT positions.
 > 
 > 
 > The document, along with other ballot positions, can be found here:
 > https://datatracker.ietf.org/doc/draft-ietf-ospf-encapsulation-cap/
 > 
 > 
 > 
 > ----------------------------------------------------------------------
 > COMMENT:
 > ----------------------------------------------------------------------
 > 
 > I think there's a normative conflict in these two pieces of text; the first one
 > from Section 3, and the second from Section 5:
 > 
 >    ...If the Encapsulation Capability
 >    TLV appears more than once in an OSPF Router Information LSA, only
 >    the first occurrence MUST be processed and others MUST be ignored.
 
[Bruno] Actually, I'm not sure why there is such restriction. Others OSPF RI allows multiple occurences. e.g. https://tools.ietf.org/html/rfc7777
Proposed NEW:
      The Tunnels Encapsulations TLV MAY appear more than once
      within a given OSPF Router Information (RI) Opaque LSA. If the Tunnels
      Encapsulations TLV appears more than once in an OSPF Router
      Information LSA, the set of all Tunnel Sub-TLVs from all Tunnels Encapsulations TLV SHOULD be considered.
 
Note: MUST is not required for interoperability as we advertise information that MAY or MAY NOT be used

 > ...
 > 
 >    Any unknown Sub-TLVs MUST be ignored and skipped upon receipt.
 > 
 >    If a Sub-TLV is invalid, its Tunnel Encapsulation TLV MUST be ignored
 >    and skipped.  However, other Tunnel Encapsulation TLVs MUST be
 >    considered.
 > 
 > The text from Section 3 says that only the first TLV [*] is to be processed --
 > but during such processing the receiver may find an invalid sub-TLV, which then
 > mandates (in Section 5) for other TLVs to be considered.
 
[Bruno] I think that the behavior is fine, however, as previously noted, the terminology is unclear.
I'm changing the terminology in -08. Could you have a look at -08 and see if this point is still unclear? Thanks.
 
 > I think that the easy solution is to change the second "MUST" from Section 3
 > for a "SHOULD".
 > 
 > It would be nice to describe what is an "invalid" sub-TLV, and that "invalid"
 > is not the same as "unknown" (right?)...but that an "unknown [tunnel] types are
 > to be ignored and skipped upon receipt", which would result in processing the
 > second (if any) TLV.

[Bruno] Proposed NEW:
Any unknown Tunnel Parameter Sub-Type MUST be ignored. When a reserved
      value (See <xref target="ParametersRegistry"/>) is seen in an LSA, it
      MUST be treated as an invalid Tunnel Parameter Sub-TLV. When a Tunnel Parameter Value has an incorrect syntax of semantic, it MUST be treated as an invalid Tunnel Parameter Sub-TLV. If a Tunnel Parameter Sub-TLV is invalid, its
      Tunnel Sub-TLV MUST be ignored and skipped. However,
      other Tunnel Sub-TLVs MUST be considered.

 > [*] Benoit's ballot pointed at the need for consistency in the names.

[Bruno] Agreed. Replying on Benoit's thread.
 
Thanks,
--Bruno

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