Re: [pim] [bess] [Idr] draft-hb-idr-sr-p2mp-policy (3/10 to 3/24/2022) - Adoption call

[Gyan Mishra <[e-mail]>]

Hi Jeffrey

Please see Gyan>


On Tue, Apr 5, 2022 at 7:38 PM Jeffrey (Zhaohui) Zhang <[e-mail]>
wrote:

> Hi Gyan,
>
>
>
> Please see zzh> below for my view.
>
>
>
>
>
> Juniper Business Use Only
>
> *From:* Gyan Mishra <[e-mail]>
> *Sent:* Tuesday, March 29, 2022 10:31 AM
> *To:* Jeffrey (Zhaohui) Zhang <[e-mail]>
> *Cc:* BESS <[e-mail]>; Bidgoli, Hooman (Nokia - CA/Ottawa) <
> [e-mail]>; Susan Hares <[e-mail]>; [e-mail];
> [e-mail]
> *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.
>

   Gyan> Ack

> 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.
>
>  Gyan> The adoption call draft is aligned with SR-TE policy as P2MP
> extension for simplicity for operators which I agree makes sense.
>
> 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.
>
>  Gyan> Ack
>
> 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).
>

    Gyan> Ack

> 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.
>

    Gyan> Both the BESS and IDR adoption draft are vastly different
solutions that have very different goals I don’t see any reason or need to
have similarities as far as TEA or SAFI encodings or usage.  The BGP
controller draft has a very wide scope, but also is more of an alternative
approach as it introduces new extensibility idea of utilizing TEA and wide
communities encoding to make the solution RFC 6513 and 6514 MVPN signaling
independent.  That is a drastic change for scalability for operations
traditional use of multicast X-PMSI P-Tree  leveraging the separation of
control plane from forwarding plane with RR using traditional MVPN
procedures.  As the ideas from the BESS draft as it builds on the BGP
Multicast draft is to eliminate soft state tree building protocols and with
the move towards hard state, thus the signaling paradigm change from
traditional MVPM procedures to alternate TEA and wide community encoding.
Am I reading that correctly as the goals of the BESS draft?  The BESS
document also mentions that the solution can be used for underlay and
overlay trees as replacement for MVPN signaling.  For underlay trees are
you referring to GTM?  I have many more questions about the BESS draft and
will ask in a new thread.

> 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 <zzhang=
> [e-mail]> 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
>
>
>
>
>
> Juniper Business Use Only
>
> *From:* Bidgoli, Hooman (Nokia - CA/Ottawa) <[e-mail]>
> *Sent:* Friday, March 25, 2022 11:34 AM
> *To:* Jeffrey (Zhaohui) Zhang <[e-mail]>; Susan Hares <
> [e-mail]>; [e-mail]
> *Cc:* '[e-mail]' <[e-mail]>; 'BESS' <[e-mail]>
> *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 <[e-mail]> *On Behalf Of *Jeffrey (Zhaohui) Zhang
> *Sent:* Friday, March 25, 2022 10:47 AM
> *To:* Susan Hares <[e-mail]>; [e-mail]
> *Cc:* '[e-mail]' <[e-mail]>; 'BESS' <[e-mail]>
> *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.
>
>
>
>
>
> Juniper Business Use Only
>
> *From:* Idr <[e-mail]> *On Behalf Of *Jeffrey (Zhaohui) Zhang
> *Sent:* Friday, March 25, 2022 6:30 AM
> *To:* Susan Hares <[e-mail]>; [e-mail]
> *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
>
>
>
>
>
> Juniper Business Use Only
>
> *From:* Idr <[e-mail]> *On Behalf Of *Susan Hares
> *Sent:* Thursday, March 10, 2022 10:28 AM
> *To:* [e-mail]
> *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:[e-mail] <[e-mail]>] *On
> Behalf Of *Susan Hares
> *Sent:* Thursday, March 10, 2022 9:55 AM
> *To:* [e-mail]; [e-mail]; [e-mail]
> *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
>
> _______________________________________________
> BESS mailing list
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>
> --
>
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>
> *Gyan Mishra*
>
> *Network Solutions Architect *
>
> *Email **[e-mail]* <[e-mail]>
>
> *M 301 502-1347*
>
>
>
-- 

<http://www.verizon.com/>

*Gyan Mishra*

*Network Solutions A**rchitect *

*Email [e-mail] <[e-mail]>*



*M 301 502-1347*