Subject: Re: [spring] Section 9.1 of the draft (IP/Optical)

From: "Ketan Talaulikar (ketant)" <[email-masked]>
Date: Thu, 1 Mar 2018 17:13:29 +0000

Hi Jeff/All,

Perhaps there is some misunderstanding on the content in the policy draft and let me try to clarify the same.

Section 4 of the policy draft introduces and describes the different Segment Types. We wanted to introduce a segment type to indicate in general a “non-IP” link that may be used to divert traffic into a link/segment as a part of an explicit segment list. This type of link could be an optical transport path, or some Layer-2 link/channel, or such. In the previous rev 04, we introduced a new Segment Type 12 for this purpose but after review/feedback, we realized that this was not necessary. Hence in the 05 version, it is clarified that Segment Type 5 or 7 may be used as such.

Section 9.1 is actually an illustration of the use-case of such a layer-2 segment type used for an SR Policy as described above. Even if the example is integrated-DWDM interface, it is clarified that the same applies for any other layer-2 or “non-IP” link representation on the router. The policy draft provides the SR Policy framework and definition.

The poi draft is very important IMHO as it covers and explains the optical transport SR Policies along with their use-cases. This draft actually specifies the Optical Transport SR policy in the form of Transport Segments – it introduces this new type of transport segment and SR policy as it references the policy draft. It also talks about the Optical Transport Policy being used through its BSID in the IP layers. This maps to Segment Type 1 in the policy draft – just similar to a SR Policy between IP segments. It is absolutely correct that the poi draft specifies the control plane extensions and TLV for the optical transport segments and capabilities. The policy draft does not do this.

So I do believe the policy and poi drafts are complementary.

Thanks,
Ketan

From: Jeff Tantsura [mailto:[email-masked]]
Sent: 01 March 2018 03:09
To: [email-masked]; [email-masked]
Cc: SPRING WG <[email-masked]>
Subject: Section 9.1 of the draft (IP/Optical)

Hello authors of draft-filsfils-spring-segment-routing-policy(further references as policy draft),

We, authors of draft-anand-spring-poi-sr draft(further referenced as poi draft) have noted that section 9.1 of 04 version of the policy draft now has IP/Optical use case, that is in great details described in the poi draft. It also references policy draft and in details explains how it could be used in IP/Optical case.

All control plane extensions needed for the solution to work are defined in the poi draft.
Rather than having 2 different drafts trying to specify same technology, we think that for the IP/Optical case a reference (normative) to the poi draft would be in place.

Thanks and looking forward to working with you!

Cheers,
Jeff on behalf of co-authors

P.S. Since Clarence is on the both drafts, I’d let him speak for himself.