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

["Jeffrey (Zhaohui) Zhang" <[e-mail]>]

Hi Gyan,

Please see zzh3> below.



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From: Gyan Mishra <[e-mail]>
Sent: Thursday, May 12, 2022 11:29 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

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Hi Jeffrey

Responses in-line Gyan3>

On Thu, May 5, 2022 at 9:43 AM Jeffrey (Zhaohui) Zhang <[e-mail]<mailto:[e-mail]>> wrote:
Hi Gyan,

Gyan2> What is the advantage of using TEA encoding as opposed to existing PTA RFC 6513 & RFC 6514 MVPN signaling?

This is about using procedures in draft-ietf-bess-bgp-multicast-controller to set up (s,g) forwarding state in a VRF, as an alternative to BGP-MVPN.
 Gyan3> Ack.  I think a drawing of service and transport controller would be good and how that plays into the operator deployment.  Would there  be a corresponding draft in PCE WG for stateful PCE instantiation of the BGP based Trees by the controller?
Zzh3> Will add a drawing in the next revision.
Zzh3> https://datatracker.ietf.org/doc/draft-li-pce-multicast/ is the PCE counter part.
As described in https://datatracker.ietf.org/doc/html/draft-ietf-bess-bgp-multicast-controller-09#section-2<https://urldefense.com/v3/__https:/datatracker.ietf.org/doc/html/draft-ietf-bess-bgp-multicast-controller-09*section-2__;Iw!!NEt6yMaO-gk!D-8-rhn36Jl-nSrpiv0mGDhH00ks-O4MceV0W9g5N73cAE2yvJFaa1mkaZ27Z0bpP8k_fOQTjb2ncW4Fl3rldQ$>, instead of ingress/egress PE figuring out the (s,g) state based on BGP-MVPN signaling and PIM signaling (for local OIFs to CEs), they simply take instructions from a control on what tunnel branches and which local OIFs to use – as if an operator is configuring them statically. This allows the PEs to be very dumb and simple.
 Gyan3>  So this is simplified MVPN signaling state paired down from RFC 6514 using same RR or eBGP mesh peering single or multi hop using MCAST-TREE SAFI new route types defined in BGP Multicast section 2 carrying the s,g hard state in BGP eliminating soft state, and extends the TEA encoding defined in BGP Multicast to as well SR use cases.
Zzh3> There was no soft state in RFC 6514 anyway. The key is that instead of PEs figuring out (s,g) forwarding state based on MVPN routes, they simply take instructions from the controller. Dumb but simple routers with omniscient/omnipotent controllers.
https://datatracker.ietf.org/doc/html/draft-ietf-bess-bgp-multicast-00#section-2.1<https://urldefense.com/v3/__https:/datatracker.ietf.org/doc/html/draft-ietf-bess-bgp-multicast-00*section-2.1__;Iw!!NEt6yMaO-gk!D-8-rhn36Jl-nSrpiv0mGDhH00ks-O4MceV0W9g5N73cAE2yvJFaa1mkaZ27Z0bpP8k_fOQTjb2ncW6NPliK9w$>


          3 -  S-PMSI A-D Route for (x,g)

          4 -  Leaf A-D Route

          5 -  Source Active A-D Route

       0x43 -  S-PMSI A-D Route for C-multicast mLDP

So RT-3 4 5 are existing RT from RFC 6514 and 0x43 is a new RT introduced in BGP multicast draft.  Does the controller draft use all 4 RTs and / or are there any additional RT used.   That should be spelled out in the draft all the MCAST-TREE SAFI RTs that carry over to the controller draft.  Also if there are any additional RFC 6514 RTs that are not included in the BGP multicast draft those should be spelled out as well.

Zzh3> RFC 6514 and bgp-mcast use different SAFIs, so the route types don’t really need to correlate with each other, even though the name/number and function bear some similarity.

I think the section 3.3 Replication state RT is the only additional to the list

From that point of view, there is no difference between “underlay” and “overlay” and the TEA is perfect to encode that information – each “tunnel” in the TEA is a replication branch.
Gyan3>Ack
That section does have the following that makes use of the PTA (attached to MCAST-TREE NLRIs for programing VRF (s,g) forwarding state):

   The Replication State route may also have a PMSI Tunnel Attribute
   (PTA) attached to specify the provider tunnel while the TEA specifies
   the local PE-CE interfaces where traffic need to be sent out.  This
   not only allows provider tunnel without a binding SID (e.g., in a
   non-SR network) to be specified without explicitly listing its
   replication branches, but also allows the service controller for MVPN
   overlay state to be independent of provider tunnel setup (which could
   be from a different transport controller or even without a
   controller).
 Gyan3> Ack
   In the draft you mention how the draft applies to SR P2MP policy and it sounds like this draft updates the PIM P2MP draft adding the new MCAST-TREE SAFI with procedures where each tunnel in TEA is a replication branch to instantiate the P2MP policy.  So  this draft is an alternative controller based option to building an SR P2MP tree using MCAST-TREE SAFI and TEA tunnel branch encoding as opposed to using Replication SID / Tree SID solution.

Zzh3> PIM SR-P2MP draft is  the “framework” document. An SR-P2MP tree can be set up with different signaling including PCEP and BGP. In the BGP case, the bess draft uses the MCAST-TREE SAFI with the same mechanisms as other tree types, while the IDR draft uses a different SAFI and mechanism for SR-P2MP only. The decision is to separate SR-P2MP out to an IDR draft and consolidate the solutions from the two drafts.

https://datatracker.ietf.org/doc/html/draft-ietf-bess-bgp-multicast-controller-09#section-1.7<https://urldefense.com/v3/__https:/datatracker.ietf.org/doc/html/draft-ietf-bess-bgp-multicast-controller-09*section-1.7__;Iw!!NEt6yMaO-gk!D-8-rhn36Jl-nSrpiv0mGDhH00ks-O4MceV0W9g5N73cAE2yvJFaa1mkaZ27Z0bpP8k_fOQTjb2ncW5JoRSkTg$>



   Procedures in this document can be used for controllers to set up SR

   P2MP trees with just an additional SR P2MP tree type and

   corresponding tree identification in the Replication State route.



   If/once the SR Replication Segment is extended to bi-redirectional,

   and SR MP2MP is introduced, the same procedures in this document

   would apply to SR MP2MP as well.



Section 3.1.1 Any Encapsulation tunnel



So would this controller procedure support I am guessing RFC 4023 MPLSoGRE RFC 7510 MPLSoUDP and

RFC 8663 SR-MPLS over IP as well as SRv6?



https://datatracker.ietf.org/doc/html/draft-ietf-bess-bgp-multicast-controller-09#section-3.1.1<https://urldefense.com/v3/__https:/datatracker.ietf.org/doc/html/draft-ietf-bess-bgp-multicast-controller-09*section-3.1.1__;Iw!!NEt6yMaO-gk!D-8-rhn36Jl-nSrpiv0mGDhH00ks-O4MceV0W9g5N73cAE2yvJFaa1mkaZ27Z0bpP8k_fOQTjb2ncW4z2dGotw$>



Maybe listing all the encapsulation tunnels supported and caveats would be good.



Zzh3> Listing them out would be limiting and could soon become outdated. The “Any Encapsulation” name means that it does not matter what base tunnel is used.

Section 3.1.2 talks about TEA enhancements adding load balancing tunnel sub TLV.  Would there also be corresponding update to SR P2MP policy as far as load balancing as load balancing can be configured by the SR policy directly?  What is the interaction between SR P2MP policy instantiation and the TEA encoding of the replication branches?


Zzh3> Do you mean policy on the tunnel root, and the candidate paths in the policy?

SR policy uses TEA already for the policy encoding

https://datatracker.ietf.org/doc/html/draft-ietf-idr-segment-routing-te-policy-17#section-2.4.4<https://urldefense.com/v3/__https:/datatracker.ietf.org/doc/html/draft-ietf-idr-segment-routing-te-policy-17*section-2.4.4__;Iw!!NEt6yMaO-gk!D-8-rhn36Jl-nSrpiv0mGDhH00ks-O4MceV0W9g5N73cAE2yvJFaa1mkaZ27Z0bpP8k_fOQTjb2ncW73iX1w8g$>

zzh3> I don’t think using TEA to encode policy information is really a good match for the TEA’s original purpose (please see https://mailarchive.ietf.org/arch/msg/idr/p0SkN-O8j5_RLyq_A21uffFZ7RM/), but that’s water under a bridge now.
Zzh3> That explains why the bess draft uses wide community to encode policy information, though I am fine with taking the TEA approach in the consolidated the idr SR-P2MP draft (even though a new BGP Path Attribute would be a better choice in my view).

Section 3.1.3 Segment list tunnel

So is something new being added or are we just reiterating section 2.4.4 of SR policy draft.  If nothing is changing and we are using the same sub TLV in SR policy section 2.4.4 maybe state that is the case.  So all the other sub TLV listed in section 3 are all new sub TLV that would update SR policy draft TEA encoding of sub TLVs, correct?  As the SR policy draft is the base draft for SR policy, here with this draft we are extending the SR policy TEA encoding with all the additional TLVs listed.

Zzh3> It’s a new tunnel type defined in this draft but it uses sub-TLVs from the policy draft.
Zzh3> Other sub TLVs in section 3 are for this new tunnel type, so they don’t update the SR policy draft.

Section 3.1.7 Backup Tunnel Sub TLV

Could this apply to unicast P2P tunnel  and not just multicast P2MP tunnel  for backup tunnel for live-live protection?

Zzh3> Yes, but I’m not trying to assert that in this draft.

Section 3.4.2 BGP Community container

SR policy draft does not use BGP Wide communities for encoding.

So this would be something new that we would be encoding the SR P2MP policy using BGP Wide Community new optional atoms TLV.

Could this also apply to unicast SR P2P policy as well?

What is the benefit of encoding the SR P2MP policy  in wide community containers versus encoding as defined in SR policy draft?

https://datatracker.ietf.org/doc/html/draft-ietf-idr-segment-routing-te-policy-17<https://urldefense.com/v3/__https:/datatracker.ietf.org/doc/html/draft-ietf-idr-segment-routing-te-policy-17__;!!NEt6yMaO-gk!D-8-rhn36Jl-nSrpiv0mGDhH00ks-O4MceV0W9g5N73cAE2yvJFaa1mkaZ27Z0bpP8k_fOQTjb2ncW4S-fpInA$>

zzh3> Please see earlier comments above.
Zzh3> Thanks.
Zzh3> Jeffrey

Jeffrey



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From: Gyan Mishra <[e-mail]<mailto:[e-mail]>>
Sent: Thursday, April 28, 2022 12:19 AM
To: Jeffrey (Zhaohui) Zhang <[e-mail]<mailto:[e-mail]>>
Cc: BESS <[e-mail]<mailto:[e-mail]>>; Bidgoli, Hooman (Nokia - CA/Ottawa) <[e-mail]<mailto:[e-mail]>>; Susan Hares <[e-mail]<mailto:[e-mail]>>; [e-mail]<mailto:[e-mail]>; [e-mail]<mailto:[e-mail]>
Subject: Re: [bess] [Idr] draft-hb-idr-sr-p2mp-policy (3/10 to 3/24/2022) - Adoption call

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Hi Jeffrey

Please see Gyan2>

On Tue, Apr 12, 2022 at 11:02 AM Jeffrey (Zhaohui) Zhang <[e-mail]<mailto:[e-mail]>> wrote:
Hi Gyan,

Please see zzh2> below.



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From: Gyan Mishra <[e-mail]<mailto:[e-mail]>>
Sent: Friday, April 8, 2022 8:48 PM
To: Jeffrey (Zhaohui) Zhang <[e-mail]<mailto:[e-mail]>>
Cc: BESS <[e-mail]<mailto:[e-mail]>>; Bidgoli, Hooman (Nokia - CA/Ottawa) <[e-mail]<mailto:[e-mail]>>; Susan Hares <[e-mail]<mailto:[e-mail]>>; [e-mail]<mailto:[e-mail]>; [e-mail]<mailto:[e-mail]>
Subject: Re: [bess] [Idr] draft-hb-idr-sr-p2mp-policy (3/10 to 3/24/2022) - Adoption call

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Hi Jeffrey

Please see Gyan>


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

Please see zzh> below for my view.



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

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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.
Zzh2> Correction – the MCAST-TREE SAFI is defined in draft-ietf-bess-bgp-multicast.

   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?

Zzh2> Not really 😊
 Gyan> Ok
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.

Zzh2> draft-ietf-bess-bgp-multicast-controller was initially intended to build traditional IP multicast trees (w/o any VPN specifics) and mLDP tunnels (started in September 2017) with calculation on and signaling from controllers. SR-P2MP was added in -03 (July 2020) because the generic mechanism for IP/mLDP trees can be used for SR-P2MP as well. These can all be considered as underlay.
    Gyan> Ack
Zzh2> Overlay support – as an MVPN replacement – was added in -06 (February 2021), but the concept is *not different* from underlay at all – we’re just setting up (s, g) IP multicast state in VRFs, with downstream nodes including remote VRFs connected by some sort of tunnels. That is not different from setting up state in global table at all.

     Gyan2> Ack

   Gyan2> What is the advantage of using TEA encoding as opposed to existing PTA RFC 6513 & RFC 6514 MVPN signaling?
Zzh2> Thanks.
Zzh2> Jeffrey
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]<mailto:[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



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

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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]<mailto:[e-mail]>> On Behalf Of Jeffrey (Zhaohui) Zhang
Sent: Friday, March 25, 2022 10:47 AM
To: Susan Hares <[e-mail]<mailto:[e-mail]>>; [e-mail]<mailto:[e-mail]>
Cc: '[e-mail]<mailto:[e-mail]>' <[e-mail]<mailto:[e-mail]>>; 'BESS' <[e-mail]<mailto:[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.



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Sent: Friday, March 25, 2022 6:30 AM
To: Susan Hares <[e-mail]<mailto:[e-mail]>>; [e-mail]<mailto:[e-mail]>
Subject: Re: [Idr] draft-hb-idr-sr-p2mp-policy (3/10 to 3/24/2022) - Adoption call

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

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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]] On Behalf Of Susan Hares
Sent: Thursday, March 10, 2022 9:55 AM
To: [e-mail]<mailto:[e-mail]>; [e-mail]<mailto:[e-mail]>; [e-mail]<mailto:[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
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Gyan Mishra

Network Solutions Architect

Email [e-mail]<mailto:[e-mail]>

M 301 502-1347

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Gyan Mishra

Network Solutions Architect

Email [e-mail]<mailto:[e-mail]>

M 301 502-1347

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Gyan Mishra

Network Solutions Architect

Email [e-mail]<mailto:[e-mail]>

M 301 502-1347

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Gyan Mishra

Network Solutions Architect

Email [e-mail]<mailto:[e-mail]>

M 301 502-1347