Re: [RTG-DIR] Rtgdir last call review of draft-ietf-isis-sr-yang-17

"Pengshuping (Peng Shuping)" <> Mon, 04 December 2023 01:40 UTC

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From: "Pengshuping (Peng Shuping)" <>
To: Yingzhen Qu <>
CC: "" <>, "" <>, "" <>, "" <>
Thread-Topic: Rtgdir last call review of draft-ietf-isis-sr-yang-17
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Date: Mon, 04 Dec 2023 01:39:58 +0000
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Subject: Re: [RTG-DIR] Rtgdir last call review of draft-ietf-isis-sr-yang-17
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Hi Yingzhen,

Your responses are good to me. Thank you!

Best regards,

From: Yingzhen Qu []
Sent: Tuesday, November 28, 2023 5:49 PM
To: Pengshuping (Peng Shuping) <>
Subject: Re: Rtgdir last call review of draft-ietf-isis-sr-yang-17

Hi Shuping,

Thanks for the review. Please see my response below inline.


On Fri, Nov 24, 2023 at 12:37 AM Shuping Peng via Datatracker <<>> wrote:
Reviewer: Shuping Peng
Review result: Has Issues


I have been selected as the Routing Directorate reviewer for this draft. The
Routing Directorate seeks to review all routing or routing-related drafts as
they pass through IETF last call and IESG review, and sometimes on special
request. The purpose of the review is to provide assistance to the Routing ADs.
For more information about the Routing Directorate, please see

Although these comments are primarily for the use of the Routing ADs, it would
be helpful if you could consider them along with any other IETF Last Call
comments that you receive, and strive to resolve them through discussion or by
updating the draft.

Document: draft-ietf-isis-sr-yang
Reviewer: Shuping Peng
Review Date: 2023-11-24
IETF LC End Date: 2023-11-30
Intended Status: Standards

I have some minor concerns about this document that I think should be resolved
before publication.

Major Issues:
 "No major issues found."

Minor Issues:
1. Page 3, when configure adjacency-sid, do we need to indicate the neighbor's
systemid or IP in order to differentiate the different neighbors in the case of
having multiple neighbors?

augment /rt:routing/rt:control-plane-protocols
    +--rw segment-routing
       +--rw adjacency-sid
          +--rw adj-sids* [value]
          |  +--rw value-type?   enumeration
          |  +--rw value         uint32
          |  +--rw protected?    boolean

[Yingzhen]:  thanks for catching this. We didn't consider LAN interfaces, will fix this in the next version.

2. Page 4, since LFA, RLFA and TI-LFA are the three algorithm for computing
backup paths, why they are not in sibling relationship?

  augment /rt:routing/rt:control-plane-protocols
    +--rw ti-lfa {ti-lfa}?
       +--rw enable?   boolean
  augment /rt:routing/rt:control-plane-protocols
    +--rw use-segment-routing-path?   boolean {remote-lfa-sr}?
[Yingzhen]: the assumption here is that LFA is preferred when available.  Although in the ti-lfa draft, it says that LFA may not be preferred over ti-lfa, however if there is LFA route available, the chance of it also being post-convergence path is very high. I'll check with the ti-lfa authors and some implementations.

3. Page 4, the keys of the global-block and local-block are not clear.

  augment /rt:routing/rt:control-plane-protocols
    +--ro sr-capability
    |  +--ro sr-capability
    |  |  +--ro sr-capability-bits*   identityref
    |  +--ro global-blocks
    |     +--ro global-block* []
    |        +--ro range-size?    uint32
    |        +--ro sid-sub-tlv
    |           +--ro sid?   uint32
    +--ro sr-algorithms
    |  +--ro sr-algorithm*   uint8
    +--ro local-blocks
    |  +--ro local-block* []
    |     +--ro range-size?    uint32
    |     +--ro sid-sub-tlv
    |        +--ro sid?   uint32
    +--ro srms-preference
       +--ro preference?   uint8

[Yingzhen]: these are read-only data, so key is not a must.

4. Currently there is no configuration node for the micro loop avoidance
any thoughts or plan on it?
[Yingzhen]: we can do an augmentation when the mentioned draft is ready to progress.