Re: [Isis-wg] WG Last Call for draft-ietf-isis-segment-routing-msd-07

Xiaohu <xuxh.mail@googlemail.com> Thu, 11 January 2018 00:35 UTC

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From: Xiaohu <xuxh.mail@googlemail.com>
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Date: Thu, 11 Jan 2018 08:35:24 +0800
Cc: Xuxiaohu <xuxiaohu@huawei.com>, "Ketan Talaulikar (ketant)" <ketant@cisco.com>, Christian Hopps <chopps@chopps.org>, "isis-wg@ietf.org" <isis-wg@ietf.org>, "isis-ads@ietf.org" <isis-ads@ietf.org>, "draft-ietf-isis-segment-routing-msd@ietf.org" <draft-ietf-isis-segment-routing-msd@ietf.org>, "draft-ietf-isis-mpls-elc.authors@ietf.org" <draft-ietf-isis-mpls-elc.authors@ietf.org>
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To: "Les Ginsberg (ginsberg)" <ginsberg@cisco.com>
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Subject: Re: [Isis-wg] WG Last Call for draft-ietf-isis-segment-routing-msd-07
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Les,

Thanks for this email. I will review this doc and then determine how to update the ISIS-ELC and OSPF-ELC drafts according.

Xiaohu 

发自我的 iPhone

> 在 2018年1月11日,02:44,Les Ginsberg (ginsberg) <ginsberg@cisco.com> 写道:
> 
> Xiaohu -
> 
> V9 of the MSD draft has been posted with the promised changes.
> Please review. I hope this leads to you revising https://datatracker.ietf.org/doc/draft-ietf-isis-mpls-elc/ to make use of the MSD sub-TLV to advertise RLD.
> 
>   Les
> 
> 
>> -----Original Message-----
>> From: Les Ginsberg (ginsberg)
>> Sent: Monday, January 08, 2018 12:13 AM
>> To: Xuxiaohu <xuxiaohu@huawei.com>om>; Ketan Talaulikar (ketant)
>> <ketant@cisco.com>om>; Christian Hopps <chopps@chopps.org>rg>; isis-
>> wg@ietf.org
>> Cc: isis-ads@ietf.org; draft-ietf-isis-segment-routing-msd@ietf.org
>> Subject: RE: [Isis-wg] WG Last Call for draft-ietf-isis-segment-routing-msd-07
>> 
>> Xiaohu -
>> 
>> Work on a revision to the MSD draft to make the names and text consistent
>> with the goal that multiple types of "MSD" will be advertised using the same
>> sub-TLV is in progress. Once authors have agreed on the changes you will see
>> a new revision.
>> 
>> Can I assume that once this is done you are open to changing the mpls-elc
>> drafts to use the more generic encoding for advertising RLD?
>> 
>> I think this is important to make judicious use of sub-TLV code points.
>> As written, https://tools.ietf.org/html/draft-ietf-isis-mpls-elc-03 requires a
>> distinct sub-TLV from the set of sub-TLVs defined for TLV 242 to advertise
>> RLD. If this model were to be applied for other types of "MSD", I can foresee
>> consumption of a significant number of sub-TLV codepoints just for all the
>> flavors of "MSD". This is one reason we defined the generic MSD sub-TLV
>> format in draft-ietf-isis-segment-routing-msd. A single sub-TLV can be used
>> to advertise as many different MSD types as necessary.
>> 
>> There are also other benefits:
>> 
>> An IGP agnostic registry is defined to assign MSD types. This means the same
>> type value can be used in OSPF, IS-IS, and in BGP-LS.
>> 
>> In IS-IS there is a small efficiency gain in that we do not have to advertise a
>> length for each MSD type.
>> 
>> I look forward to feedback from you once the new revision of the MSD draft
>> is published.
>> 
>> Thanx.
>> 
>>   Les
>> 
>> 
>> 
>>> -----Original Message-----
>>> From: Xuxiaohu [mailto:xuxiaohu@huawei.com]
>>> Sent: Wednesday, December 20, 2017 6:40 PM
>>> To: Les Ginsberg (ginsberg) <ginsberg@cisco.com>om>; Ketan Talaulikar
>>> (ketant) <ketant@cisco.com>om>; Christian Hopps <chopps@chopps.org>rg>;
>>> isis- wg@ietf.org
>>> Cc: isis-ads@ietf.org; draft-ietf-isis-segment-routing-msd@ietf.org
>>> Subject: 答复: [Isis-wg] WG Last Call for
>>> draft-ietf-isis-segment-routing-msd-
>>> 07
>>> 
>>> Hi Les,
>>> 
>>> If I understand it correctly, the MSD concept was originated from
>>> (https://tools.ietf.org/html/draft-ietf-pce-segment-routing-11#page-7)
>>> as described below:
>>> 
>>> "The "Maximum SID Depth" (1
>>>   octet) field (MSD) specifies the maximum number of SIDs (MPLS label
>>>   stack depth in the context of this document) that a PCC is capable of
>>>   imposing on a packet."
>>> 
>>> Before considering expanding the semantics of the MSD concept as
>>> defined in the above PCE-SR draft, how about first considering
>>> renaming the capability of imposing the maximum number of labels so as
>>> to eliminate possible confusions, e.g., Writable Label-stack Depth
>>> (WLD) as opposed to the Readable Label-stack Depth (RLD) as defined in
>>> (https://tools.ietf.org/html/draft-ietf-ospf-mpls-elc) and
>>> (https://tools.ietf.org/html/draft-ietf-isis-mpls-elc) ?
>>> 
>>> Best regards,
>>> Xiaohu
>>> 
>>>> -----邮件原件-----
>>>> 发件人: Isis-wg [mailto:isis-wg-bounces@ietf.org] 代表 Les Ginsberg
>>>> (ginsberg)
>>>> 发送时间: 2017年12月21日 4:02
>>>> 收件人: Ketan Talaulikar (ketant); Christian Hopps; isis-wg@ietf.org
>>>> 抄送: isis-ads@ietf.org; draft-ietf-isis-segment-routing-msd@ietf.org
>>>> 主题: Re: [Isis-wg] WG Last Call for
>>>> draft-ietf-isis-segment-routing-msd-07
>>>> 
>>>> Ketan -
>>>> 
>>>> Thanx for the comments.
>>>> I think we do want to allow MSD support for values other than
>>>> imposition values. We will revise the text so we are not restricted
>>>> to only
>>> imposition cases.
>>>> 
>>>>  Les
>>>> 
>>>> 
>>>>> -----Original Message-----
>>>>> From: Ketan Talaulikar (ketant)
>>>>> Sent: Wednesday, December 20, 2017 1:51 AM
>>>>> To: Christian Hopps <chopps@chopps.org>rg>; isis-wg@ietf.org
>>>>> Cc: isis-ads@ietf.org;
>>>>> draft-ietf-isis-segment-routing-msd@ietf.org
>>>>> Subject: RE: [Isis-wg] WG Last Call for
>>>>> draft-ietf-isis-segment-routing-msd-07
>>>>> 
>>>>> Hello,
>>>>> 
>>>>> I support this document and would like to ask the authors and WG
>>>>> to consider if we can expand the scope of this draft to not just
>>>>> "imposition" of the SID stack but also other similar limits
>>>>> related to other
>>>> actions (e.g.
>>>>> reading, processing, etc.). With Segment Routing, we are coming
>>>>> across various actions that nodes need to do with the SID stack
>>>>> for different purposes and IMHO it would be useful to extend the
>>>>> MSD ability to cover those as they arise.
>>>>> 
>>>>> Thanks,
>>>>> Ketan
>>>>> 
>>>>> -----Original Message-----
>>>>> From: Isis-wg [mailto:isis-wg-bounces@ietf.org] On Behalf Of
>>>>> Christian Hopps
>>>>> Sent: 20 December 2017 14:03
>>>>> To: isis-wg@ietf.org
>>>>> Cc: isis-ads@ietf.org;
>>>>> draft-ietf-isis-segment-routing-msd@ietf.org
>>>>> Subject: [Isis-wg] WG Last Call for
>>>>> draft-ietf-isis-segment-routing-msd-07
>>>>> 
>>>>> 
>>>>> The authors have asked for and we are starting a WG Last Call on
>>>>> 
>>>>> 
>>>>> https://datatracker.ietf.org/doc/draft-ietf-isis-segment-routing-m
>>>>> sd
>>>>> /
>>>>> 
>>>>> which will last an extended 4 weeks to allow for year-end PTO patterns.
>>>>> 
>>>>> An IPR statement exists:
>>>>> 
>>>>> 
>>>>> https://datatracker.ietf.org/ipr/search/?submit=draft&id=draft-iet
>>>>> f-
>>>>> is
>>>>> is-
>>>>> segment-routing-msd
>>>>> 
>>>>> Authors please reply to the list indicating whether you are aware
>>>>> of any
>>>>> *new* IPR.
>>>>> 
>>>>> Thanks,
>>>>> Chris.
>>>>> 
>>>>> _______________________________________________
>>>>> Isis-wg mailing list
>>>>> Isis-wg@ietf.org
>>>>> https://www.ietf.org/mailman/listinfo/isis-wg
>>>> 
>>>> _______________________________________________
>>>> Isis-wg mailing list
>>>> Isis-wg@ietf.org
>>>> https://www.ietf.org/mailman/listinfo/isis-wg