Re: [Idr] Part 3 of CAR/CT Adoption call (7/14/2022 to 7/27/2022) - Operational Differences

["Dhananjaya Rao (dhrao)" <[e-mail]>]

Hi Jinrong,

Thank you for your question, apologies for the delay in getting to it.

BGP-CAR SAFI is designed to support multiple transports consistently, and the current version describes the encoding mechanisms for SRv6.

As you probably gauged from the illustrations in the current version, the BGP-CAR control/dataplane flows for MPLS maintain consistency with the model established and deployed with BGP-LU. The approach would be similar for SRv6, where CAR leverages base SRv6 routing mechanisms already described in SRv6-overlay (RFC9252) and SRv6-MPLS interworking draft (draft-agrawal-spring-srv6-mpls-interworking).

However, there are additional options and operational considerations that do need to be described. We plan to include them along with illustrations in the next version of the draft.

Thank you for the draft reference. We will also review it.

Regards,
-Dhananjaya

From: Idr <[e-mail]> on behalf of "Xiejingrong (Jingrong)" <xiejingrong=[e-mail]>
Date: Tuesday, July 26, 2022 at 11:56 AM
To: Susan Hares <[e-mail]>, "[e-mail]" <[e-mail]>
Subject: Re: [Idr] Part 3 of CAR/CT Adoption call (7/14/2022 to 7/27/2022) - Operational Differences


Hi Working group:

I have received the response from Rajesh about the SRv6 data-plane of CT, very much appreciated.
I am still waiting for response and discussion from CAR about the detail of SRv6 data-plane support.
At the meantime, we detailed the thoughts and submitted a draft on this: https://datatracker.ietf.org/doc/draft-wang-idr-cpr/
Hope it is helpful to the discussion about the SRv6 data-plane support for e2e intent aware paths.

Regards,
Jingrong

From: Idr [mailto:[e-mail]] On Behalf Of Xiejingrong (Jingrong)
Sent: Friday, July 22, 2022 11:04 AM
To: Rajesh M <mrajesh=[e-mail]>; Susan Hares <[e-mail]>; [e-mail]
Subject: Re: [Idr] Part 3 of CAR/CT Adoption call (7/14/2022 to 7/27/2022) - Operational Differences

Hi Rajesh,

Thank you very much for providing the reading guidance.
I have read the related draft <draft-salih-spring-srv6-inter-domain-sids>, and the following is my understanding of the data plane:

(use the simple topology in the draft section 5.1 and 3.1)
{[1]----[2]----[4]}……{[6]----[8]----[10]}……{[12]----[15]----[16]}

1->2: (S=1, D=2)(16.DT4, B:4:REP::1, SL=2) (Customer-pkt)
2->4: (S=1, D=B:4:REP::1)(16.DT4, B:4:REP::1, SL=1) (Customer-pkt)
4->6: (S=1, D=B:6:REP6::1)(16.DT4, B:4:REP::1, SL=1) (Customer-pkt)
6->8: (S=6, D=8)(10, SL=1), (S=1, D=B:10:REP::1)(16.DT4, B:4:REP::1, SL=1) (Customer-pkt)
8->10: (S=6, D=10)(10, SL=0), (S=1, D=B:10:REP::1)(16.DT4, B:4:REP::1, SL=1) (Customer-pkt)
10->12: (S=1, D=B:12:REP6::1)(16.DT4, B:4:REP::1, SL=1) (Customer-pkt)
12->14: (S=12, D=14)(B:16:END::1, SL=1), (S=1, D= B:16:END::1)(16.DT4, B:4:REP::1, SL=1) (Customer-pkt)
14->16: (S=12, D= B:16:END::1)(B:16:END::1, SL=0), (S=1, D= B:16:END::1)(16.DT4, B:4:REP::1, SL=1) (Customer-pkt)

Representation remark:
(1) The red text is encap/decap procedure.
(2) The SRH is in “Reduced variant” mode as defined in RFC8754 section 4.1.
(3) the representation of SRH is using the representation of RFC8754 section 6.2.

Please let me know if the above understanding is correct.

Jingrong


From: Rajesh M [mailto:mrajesh=[e-mail]]
Sent: Thursday, July 21, 2022 12:51 PM
To: Xiejingrong (Jingrong) <[e-mail]<mailto:[e-mail]>>; Susan Hares <[e-mail]<mailto:[e-mail]>>; [e-mail]<mailto:[e-mail]>
Subject: RE: [Idr] Part 3 of CAR/CT Adoption call (7/14/2022 to 7/27/2022) - Operational Differences

HI Jingrong,

Thanks for bringing the valid point.


Regarding CT , this has been well explained in below draft at “section 5.1.  Option C Transport Interworking”.
https://datatracker.ietf.org/doc/draft-salih-spring-srv6-inter-domain-sids/

The example shows IBGP-CT connection between border routers in each domain and single hop EBGP-CT for inter-domain connections.



Please note, CT can support any srv6 requirement.



Thanks

Rajesh





Juniper Business Use Only
From: Idr <[e-mail]<mailto:[e-mail]>> On Behalf Of Xiejingrong (Jingrong)
Sent: Tuesday, July 19, 2022 2:59 PM
To: Susan Hares <[e-mail]<mailto:[e-mail]>>; [e-mail]<mailto:[e-mail]>
Subject: Re: [Idr] Part 3 of CAR/CT Adoption call (7/14/2022 to 7/27/2022) - Operational Differences

[External Email. Be cautious of content]

Dear authors of CAR/CT, and working group:

Both the drafts say they support SRv6 as well as MPLS data plane, but neither one has clear illustration how it may support.
Can the authors please provide an illustration of SRv6 data plane (e.g., E2E SRv6 & intra-domain SRv6) based on a sample topology ?
My feeling is that the difference in the encapsulation of SRv6 and SR-MPLS/MPLS may need to be considered and may have impact on the choice.

(following is a sample topology I am used to understand multi-domain network, where BR is ASBR, [AC1-P1-BR1] is an IGP domain, [BR3-BR4] is an IGP domain, and [BR2-P2-AC2] is an IGP domain)
[AC1----P1----BR1]----[BR3----BR4]----[BR2----P2 ----AC2]

Thank you very much.

Jingrong


From: Idr [mailto:[e-mail]] On Behalf Of Susan Hares
Sent: Friday, July 15, 2022 4:17 AM
To: [e-mail]<mailto:[e-mail]>
Subject: [Idr] Part 3 of CAR/CT Adoption call (7/14/2022 to 7/27/2022) - Operational Differences

The IDR Adoption call for CAR and CT technologies is extended for an extra week
(7/14/2022 to 7/27/2022).

The IDR adoption call on Q2 has brought many discussions on pro/cons of the CAR
and CT BGP technologies:
https://mailarchive.ietf.org/arch/msg/idr/AP_ClbZgpkX6CNy7TaZiU8SMD5w/<https://urldefense.com/v3/__https:/mailarchive.ietf.org/arch/msg/idr/AP_ClbZgpkX6CNy7TaZiU8SMD5w/__;!!NEt6yMaO-gk!CFnV3YRNlDWJvDd4D_J4NEH8TegI9bicDjQoTgPKVJDXHSgsTd4YZM_c5BUhUJ4BBK1haNnneIotPlNRfnnm4Z__WPXx_x8$>

Since the IDR chairs agree with the summary of Jeff Haas (IDR Co-chair) posted on March 21, 2022 –
that for route resolution and route origination/propagation, BGP-CAR and BGP-CT
are functionally identical, but operationally different.
    ( https://mailarchive.ietf.org/arch/msg/idr/e69NRd9i2aG0WUxFkShEfQHZsHo/<https://urldefense.com/v3/__https:/mailarchive.ietf.org/arch/msg/idr/e69NRd9i2aG0WUxFkShEfQHZsHo/__;!!NEt6yMaO-gk!CFnV3YRNlDWJvDd4D_J4NEH8TegI9bicDjQoTgPKVJDXHSgsTd4YZM_c5BUhUJ4BBK1haNnneIotPlNRfnnm4Z__hmcp9g0$>

This forum (Part 3) is place to discuss operational differences between the CAR and CT drafts.

These procedures for this mail thread are:

A.     On original discussion on point in a draft
1.       Text in either the CAR or CT draft that is applicable to the operational difference.
2.       Provide a sample topology.
3.       Discuss the pros/cons clearly stating whether your post is a: pro, con, or clarifying question.
Try to split clarifying question posts away from pro/con posts. Remember, you can post to this forum several times.
In your technical discussion, define your terms and avoid value judgement.


B.      On a discussion based on message in Q2 or Q1 mail list:
1.       Quote and link to Q1 or Q2 forum’s message.
2.       Text in either the CAR or CT draft that is applicable to the problem
      (Either provide the text or give specific reference (section, paragraph, and line(s)).

3.       Provide a sample topology.
4.       Summarize your viewpoint as: correction, clarifying question, pro, or con.
5.       Discuss the pro/con or text giving technical discussion.
In your technical discussion avoid define terms, give specific
examples in terms of draft text, sample topology, and facts.
If you state an opinion, back it up with technical facts.

If you are making a correction, assume the other person either misunderstood
or has a difference of opinion.  Respect each other as each IDR member is
entitled to their opinion. As a group we are working toward excellent BGP
in deployed technology.

In your delightful passion on these two technology additions to BGP (CAR and CT), please adhere to these rules.

Thank you, Susan Hares