Re: [Softwires] Tsvart last call review of draft-ietf-softwire-iftunnel-04

<mohamed.boucadair@orange.com> Thu, 09 May 2019 07:49 UTC

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From: <mohamed.boucadair@orange.com>
To: David Black <david.black@dell.com>, "tsv-art@ietf.org" <tsv-art@ietf.org>
CC: "softwires@ietf.org" <softwires@ietf.org>, "ietf@ietf.org" <ietf@ietf.org>, "draft-ietf-softwire-iftunnel.all@ietf.org" <draft-ietf-softwire-iftunnel.all@ietf.org>
Thread-Topic: Tsvart last call review of draft-ietf-softwire-iftunnel-04
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Date: Thu, 9 May 2019 07:49:50 +0000
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Subject: Re: [Softwires] Tsvart last call review of draft-ietf-softwire-iftunnel-04
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Hi David, 

Thank you for the review. 

Please see inline.

Cheers,
Med

> -----Message d'origine-----
> De : David Black via Datatracker [mailto:noreply@ietf.org]
> Envoyé : mercredi 8 mai 2019 00:46
> À : tsv-art@ietf.org
> Cc : softwires@ietf.org; ietf@ietf.org; draft-ietf-softwire-
> iftunnel.all@ietf.org
> Objet : Tsvart last call review of draft-ietf-softwire-iftunnel-04
> 
> Reviewer: David Black
> Review result: Not Ready
> 
> This document has been reviewed as part of the transport area review team's
> ongoing effort to review key IETF documents. These comments were written
> primarily for the transport area directors, but are copied to the document's
> authors and WG to allow them to address any issues raised and also to the
> IETF discussion list for information.
> 
> When done at the time of IETF Last Call, the authors should consider this
> review as part of the last-call comments they receive. Please always CC
> tsv-art@ietf.org if you reply to or forward this review.
> 
> This draft defines a YANG module for tunnel types based on the MIB-2
> tunnel type registry maintained by IANA.
> 
> My fundamental concern with this draft is that the MIB-2 tunnel type
> registry is seriously incomplete and out of date, as there are a large
> number of tunnel types that aren't included in that registry, e.g., IPsec
> tunnel-mode AMT tunneling.  In its current form, that registry does not
> appear to be a good starting point for specifying YANG management of
> tunnels.
> 
> A limited justification that I could envision for defining this YANG module
> would be to use it for mechanical translations to YANG of existing MIBs
> that use MIB-2 tunnel types - if that's the justification, then it would need
> to be clearly stated in an applicability statement within this draft,

[Med] The intent of the draft is to reflect the current registered tunnels types. This is mentioned in the introduction:

   This document specifies the initial version of the iana-tunnel-type
                               ^^^^^^^^^^^^^^
   YANG module identifying tunnel interface types.  The module reflects
                                                               ^^^^^^^^   
   IANA's registry maintained at [TUNNELTYPE-IANA-REGISTRY].  The latest
   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   revision of this module can be obtained from the IANA web site.

 and the
> discussion of extension of this YANG module would need to be aligned with
> that limited applicability.

[Med] This is an IANA-maintained module. That is, when a new tunnel type is registered, the module will be automatically updated to include that new type identity: 

      When this registry is modified, the YANG module iana-tunnel-type
      must be updated as defined in RFCXXXX.

> 
> The proverbial "right thing to do" would be to update both the MIB-2 tunnel
> type registry and this draft with all of the currently known tunnel types.

[Med] Registering new tunnel types is not in the scope set for this draft. It is up to the documents defining these tunnel types or making use of them to make a request to IANA. For example, this is the approach followed in softwire wg for at least three tunnel types (16, 17, 18).  

> The references section of draft-ietf-tsvwg-rfc6040update-shim
> (https://datatracker.ietf.org/doc/draft-ietf-tsvwg-rfc6040update-shim/)
> may help in identifying tunnel protocols that should be included.
> 
> A minor concern involves the use of RFC 8085 as the reference for UDP
> tunnels; while that's certainly better than the existing use of RFC 4087, due
> to the extensive design guidance in RFC 8085, designers of UDP-encapsulated
> tunnel protocols ought to be encouraged to register their protocols as
> separate
> tunnel types (e.g., so the network operator has some idea of what the UDP
> tunnel is actually being used for).  This draft ought to encourage tunnel
> protocol designers to register their own tunnel types in preference to reuse
> of the UDP tunnel type, including placing text in the IANA tunnel type
> registry and this YANG module to encourage that course of action.
> 

[Med] Wouldn't that recommendation be better added to documents such as: https://tools.ietf.org/html/draft-thaler-iftype-reg-02?