Hi Gyan,

Please see zzh> below for my view.



Juniper Business Use Only
From: Gyan Mishra <[email protected]>
Sent: Tuesday, March 29, 2022 10:31 AM
To: Jeffrey (Zhaohui) Zhang <[email protected]>
Cc: BESS <[email protected]>; Bidgoli, Hooman (Nokia - CA/Ottawa) 
<[email protected]>; Susan Hares <[email protected]>; [email protected]; 
[email protected]
Subject: Re: [bess] [Idr] draft-hb-idr-sr-p2mp-policy (3/10 to 3/24/2022) - 
Adoption call

[External Email. Be cautious of content]


Dear authors

Can you describe in more detail the relationship and interaction between the 
two SR P2MP variants below:

Defines new SAFI for SR P2MP variant
https://datatracker.ietf.org/doc/html/draft-hb-idr-sr-p2mp-policy-04<https://urldefense.com/v3/__https:/datatracker.ietf.org/doc/html/draft-hb-idr-sr-p2mp-policy-04__;!!NEt6yMaO-gk!RNg1gSHc7bgU2dou9enCSiVF-PXIWQ2Wk4mTxBBHjYxjFPb_mdHB9D5C3jKh83Sr$>

zzh> draft-ietf-bess-bgp-multicast-controller (referred to as draft-bess) 
defines a SAFI and different route types of that SAFI to setup replication 
state on IP/mLDP/SR-P2MP tree nodes. One of the route types is for SR-P2MP 
purposes.
Zzh> draft-hb-idr-sr-p2mp-policy (draft in this adoption call, referred to as 
draft-hb) defines a different SAFI and route types for the same SR-P2MP 
purposes.

Does this draft utilize all the drafts below Tree sid / Replication sid and SR 
P2MP MVPN procedures for auto discovery etc.

Zzh> Both drafts are for realizing the two tree-sid drafts mentioned below; 
both can be used for draft-ietf-bess-mvpn-evpn-sr-p2mp.

Zzh> As I mentioned before, both draft-bess and draft-hb have its own 
considerations. The biggest difference is how the replication information is 
encoded in the Tunnel Encapsulation Attribute (TEA).
Zzh> I can understand that the IDR/PIM/BESS WGs may decide to accept both ways 
of encoding replication information in the TEA, but I believe we should share 
SAFI and route types between the two drafts - only the TEA would be different.
Zzh> Jeffrey

Defines Tree SID stitching of replication SID SR policy P2MP variant
https://datatracker.ietf.org/doc/html/draft-voyer-pim-sr-p2mp-policy-00<https://urldefense.com/v3/__https:/datatracker.ietf.org/doc/html/draft-voyer-pim-sr-p2mp-policy-00__;!!NEt6yMaO-gk!RNg1gSHc7bgU2dou9enCSiVF-PXIWQ2Wk4mTxBBHjYxjFPb_mdHB9D5C3gdi0hAB$>

Replication SID
https://datatracker.ietf.org/doc/html/draft-ietf-spring-sr-replication-segment<https://urldefense.com/v3/__https:/datatracker.ietf.org/doc/html/draft-ietf-spring-sr-replication-segment__;!!NEt6yMaO-gk!RNg1gSHc7bgU2dou9enCSiVF-PXIWQ2Wk4mTxBBHjYxjFPb_mdHB9D5C3smIMNzh$>

Defines new SR P2MP PTA using MVPN procedures
https://datatracker.ietf.org/doc/html/draft-ietf-bess-mvpn-evpn-sr-p2mp<https://urldefense.com/v3/__https:/datatracker.ietf.org/doc/html/draft-ietf-bess-mvpn-evpn-sr-p2mp__;!!NEt6yMaO-gk!RNg1gSHc7bgU2dou9enCSiVF-PXIWQ2Wk4mTxBBHjYxjFPb_mdHB9D5C3g-W3jH0$>


Kind Regards

Gyan


On Mon, Mar 28, 2022 at 3:39 PM Jeffrey (Zhaohui) Zhang 
<[email protected]<mailto:[email protected]>> 
wrote:
Hi,

When it comes to SR-P2MP state downloading, there are three aspects involved 
here:


  1.  NLRI to encode policy information
  2.  NLRI to encode <tree/path/instance, node> identification
  3.  Tunnel Encapsulation Attribute (TEA) that encodes actual replication 
branches

The major difference between the two ways is on #3. Indeed, we could not reach 
consensus - there are two ways of encoding the TEA and each has its own 
considerations. The draft-ietf-bess way (even when used for SR-P2MP) is aligned 
with other non-SR multicast trees (IP/mLDP) for a unified approach, while 
draft-hb is aligned to unicast BGP SR policy.

I want to initiate a discussion and I can understand that WGs may eventually 
choose to allow both ways for #3. Even so, I think we should strive for 
consistent approach at least for #1 and #2 (and for that I am not saying that 
draft-ietf-bess way must be used). For example, use the same SAFI and route 
types for both ways, but use different TEA encoding methods.

Thanks.

Jeffrey



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From: Bidgoli, Hooman (Nokia - CA/Ottawa) 
<[email protected]<mailto:[email protected]>>
Sent: Friday, March 25, 2022 11:34 AM
To: Jeffrey (Zhaohui) Zhang <[email protected]<mailto:[email protected]>>; 
Susan Hares <[email protected]<mailto:[email protected]>>; 
[email protected]<mailto:[email protected]>
Cc: '[email protected]<mailto:[email protected]>' 
<[email protected]<mailto:[email protected]>>; 'BESS' 
<[email protected]<mailto:[email protected]>>
Subject: RE: [Idr] draft-hb-idr-sr-p2mp-policy (3/10 to 3/24/2022) - Adoption 
call

[External Email. Be cautious of content]

Hi All

Zzh> I do think BGP signaling for SR P2MP is appropriate. We just need to 
discuss the two ways and figure out how to proceed. The authors have discussed 
before though we have not reached consensus.

HB> yes there was discussion and there was no consensus to merge the 2 drafts 
as their approach is widely different. The authors of this draft have kept the 
implementation very close to unicast BGP SR Policy for the segment list, which 
simplifies the implementation and deployment of the technology. As you said 
there seems to be two way to download this policy and the segment list and we 
can work on both.
Given the solid support I don't see why the adoption of this draft should  be 
delayed because of these arguments.

Thanks
Hooman

From: pim <[email protected]<mailto:[email protected]>> On Behalf Of 
Jeffrey (Zhaohui) Zhang
Sent: Friday, March 25, 2022 10:47 AM
To: Susan Hares <[email protected]<mailto:[email protected]>>; 
[email protected]<mailto:[email protected]>
Cc: '[email protected]<mailto:[email protected]>' 
<[email protected]<mailto:[email protected]>>; 'BESS' 
<[email protected]<mailto:[email protected]>>
Subject: Re: [pim] [Idr] draft-hb-idr-sr-p2mp-policy (3/10 to 3/24/2022) - 
Adoption call

[+ BESS, PIM]

Hi,

I realized that in a hurry I did not respond to the specific questions below. 
Please see zzh> next to the questions.

Looks like that there are some comments on BESS/PIM list and I will go through 
those to see if I have any addition/follow-up on those.



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From: Idr <[email protected]<mailto:[email protected]>> On Behalf Of 
Jeffrey (Zhaohui) Zhang
Sent: Friday, March 25, 2022 6:30 AM
To: Susan Hares <[email protected]<mailto:[email protected]>>; 
[email protected]<mailto:[email protected]>
Subject: Re: [Idr] draft-hb-idr-sr-p2mp-policy (3/10 to 3/24/2022) - Adoption 
call

[External Email. Be cautious of content]

I am sorry for responding late. I somehow missed this.

I think we should discuss the relationship with 
daft-ietf-bess-bgp-multicast-controller further before adopting this.

Thanks.
Jeffrey



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From: Idr <[email protected]<mailto:[email protected]>> On Behalf Of 
Susan Hares
Sent: Thursday, March 10, 2022 10:28 AM
To: [email protected]<mailto:[email protected]>
Subject: Re: [Idr] draft-hb-idr-sr-p2mp-policy (3/10 to 3/24/2022) - Adoption 
call

[External Email. Be cautious of content]

IDR WG:

If you just wish to respond to the IDR list,
you may respond to this email on the adoption call.

Cheers, Sue

From: Idr [mailto:[email protected]] On Behalf Of Susan Hares
Sent: Thursday, March 10, 2022 9:55 AM
To: [email protected]<mailto:[email protected]>; [email protected]<mailto:[email protected]>; 
[email protected]<mailto:[email protected]>
Subject: [Idr] draft-hb-idr-sr-p2mp-policy (3/10 to 3/24/2022)

This begins a 2 week WG adoption call for:
draft-hb-idr-sr-p2mp-policy from (3/10 to 3/24/2022)

You can obtain the draft at:
https://datatracker.ietf.org/doc/draft-hb-idr-sr-p2mp-policy/<https://urldefense.com/v3/__https:/datatracker.ietf.org/doc/draft-hb-idr-sr-p2mp-policy/__;!!NEt6yMaO-gk!TfiPI1NfecN3db3pj6WZ8paxUr4s6OvmVZ91mapddPFeCkFZJodxFk8aTGCpYg34$>

In your comments for this call please consider:

Zzh> I want to point out that 
https://datatracker.ietf.org/doc/draft-ietf-bess-bgp-multicast-controller/<https://urldefense.com/v3/__https:/datatracker.ietf.org/doc/draft-ietf-bess-bgp-multicast-controller/__;!!NEt6yMaO-gk!S33KKHGKJVywLaE5hTpBZvb2Og_8GrdduTTT-6xmknLUl8Yylk7RNo3lGazDpUZk$>
 is another way to do the same. I also explained in 
https://mailarchive.ietf.org/arch/msg/idr/KObeSgKPu3HRbd0ZN7L7fWq_Eto/<https://urldefense.com/v3/__https:/mailarchive.ietf.org/arch/msg/idr/KObeSgKPu3HRbd0ZN7L7fWq_Eto/__;!!NEt6yMaO-gk!S33KKHGKJVywLaE5hTpBZvb2Og_8GrdduTTT-6xmknLUl8Yylk7RNo3lGW1pXg_c$>
 why it was in the bess WG.
Zzh> In addition, the bess draft supports *other* multicast trees (IP, mLDP 
besides SR-P2MP) using a consistent way.

1)  Does this technology support the SR P2MP features
that distributes candidate paths which connect
a multicast distribution tree (tree to leaves).

Zzh> It is one way to use BGP to support that. The bess draft specifies another 
way.

2) Is the technology correctly specified for the
NLRI (AFI/SAFI) and the tunnel encapsulation attribute
additions (sections 2 and 3)?

Zzh> The specified SAFI and tunnel encapsulation attribute additions are one 
way for the BGP signaling for SR-P2MP. The bess draft specifies another way.

3) Does the P2MP policy operation (section 4)
provide enough information for those implementing this
technology and those deploying the technology?

4) Do you think this multicast technology is a good
Place to start for P2MP policy advertisement via BGP?

Zzh> Both ways are good place to start. We just need to figure out how to 
proceed with the two proposals.

5) Do you think this SR P2MP policies should not be advertised
via BGP?

Zzh> I do think BGP signaling for SR P2MP is appropriate. We just need to 
discuss the two ways and figure out how to proceed. The authors have discussed 
before though we have not reached consensus.
Zzh> Thanks!
Zzh> Jeffrey

Cheers, Susan Hares
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Gyan Mishra

Network Solutions Architect

Email [email protected]<mailto:[email protected]>

M 301 502-1347

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