Re: [OSPF] Working group last call on draft-ietf-mpls-residence-time

"Les Ginsberg (ginsberg)" <ginsberg@cisco.com> Mon, 30 January 2017 21:12 UTC

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From: "Les Ginsberg (ginsberg)" <ginsberg@cisco.com>
To: Loa Andersson <loa@pi.nu>, "mpls@ietf.org" <mpls@ietf.org>, TEAS WG <teas@ietf.org>, "ospf@ietf.org" <ospf@ietf.org>, Isis-wg <isis-wg-bounces@ietf.org>
Thread-Topic: [OSPF] Working group last call on draft-ietf-mpls-residence-time
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Date: Mon, 30 Jan 2017 21:11:41 +0000
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Subject: Re: [OSPF] Working group last call on draft-ietf-mpls-residence-time
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Loa -



The change for IS-IS encoding to utilize a sub-TLV of TLV 22 et al to advertise RTM capability is a better solution than the previous proposal and this has my support.

However, there are some details as regards the proposed sub-TLV that should be revised.



1)Rather than use a fixed 16 bit field for the flags I suggest you utilize the encoding style introduced in RFC 7794 (see Section 2.1) which allows for a variable length flags field. This addresses two issues:



   o You need never worry that the size of the flags field will be too small for future extensions

   o It minimizes the number of bytes required to be sent



The latter point is something IS-IS has always been more conservative about than OSPF because of the fixed size of an LSP set which can be advertised by a single router.



2)In the IANA considerations you have limited the sub-TLV to being used in TLV 22 only, but there is no reason to do so. This does not allow MT to be supported and it needlessly prevents use of the sub-TLV by the RFC 5311 extensions (however unpopular those may be). I can understand why the sub-TLV may not be useful in TLV 141, therefore I suggest the table in Section 7.5 be revised to be:





    | Type | Description | 22 | 23 | 141 | 222 | 223 | Reference     |

   +------+-------------+----+----+-----+-----+-----+---------------+

  | TBA3 |    RTM       | y  | y  | n   | y   | y   | This document |

    +------+-------------+----+----+-----+-----+-----+---------------+



i.e. "y" for all but TLV 141 (in case the ASCII art doesn't translate well in your mailer).


You should also remove the reference to RFC 5305 in Section 4.5 as it is too limiting. Simply referencing the IANA registry http://www.iana.org/assignments/isis-tlv-codepoints/isis-tlv-codepoints.xhtml#isis-tlv-codepoints-22-23-141-222-223<http://www.iana.org/assignments/isis-tlv-codepoints/isis-tlv-codepoints.xhtml%23isis-tlv-codepoints-22-23-141-222-223> should be sufficient. All necessary references can be found there.



3)An editorial correction:



Introduction 3rd paragraph:



s/ Althugh/ Although



   Les



> -----Original Message-----

> From: OSPF [mailto:ospf-bounces@ietf.org] On Behalf Of Loa Andersson

> Sent: Monday, January 30, 2017 8:02 AM

> To: mpls@ietf.org; TEAS WG; ospf@ietf.org; Isis-wg

> Cc: isis-chairs@ietf.org; draft-ietf-mpls-residence-time@tools.ietf.org; TEAS

> WG Chairs; mpls-chairs@ietf.org; ospf-chairs@ietf.org

> Subject: [OSPF] Working group last call on draft-ietf-mpls-residence-time

>

> Working Groups,

>

> This is to initiate a two week working group last call in four working groups on

> draft-ietf-mpls-residence-time-13.

>

> The MPLS working group has done an earlier working group last call and a

> request for publication has been made.

>

> The changes to the document were such that we decided to do a new

> working group last call and extend it to MPLS, TEAS, OSPF and IS-IS.

>

> There are three major changes between the version of the document for

> which publication was requested are:

>

> (1) that section 7 " One-step Clock and Two-step Clock Modes" has been

>      moved up to become section 2.1.

> (2) that a sub-TLV for TLV 22 instead of TLV 251 is used to RTM

>      Capability when IS-IS used advertise RTM capabilities

> (3) BGP-LS has been added as a RTM capability advertisement method

>

> A side-by-side diff between version -12 and -13 is available at:

> https://www.ietf.org/rfcdiff?url2=draft-ietf-mpls-residence-time-13

>

> Please send your comments to the mpls wg mailing list (mpls@ietf.org<mailto:mpls@ietf.org>), if

> you are not subscribed to the mpls wg list, send to "your own"

> working group mailing list, and we'll make sure they are posted to the MPLS

> wg list.

>

> There were one IPR disclosure against this document.

>

> All the authors and contributors have stated on the working group mailing list

> that they are not aware of any other IPRs that relates to this document.

>

> This working group last call ends February 13, 2017.

>

>

> /Loa

> MPLS wg co-chairs

> --

>

>

> Loa Andersson                        email: loa@mail01.huawei.com<mailto:loa@mail01.huawei.com>

> Senior MPLS Expert                          loa@pi.nu<mailto:loa@pi.nu>

> Huawei Technologies (consultant)     phone: +46 739 81 21 64

>

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