Rishabh,

Pls see inline..



Juniper Business Use Only
From: Rishabh Parekh <risha...@gmail.com>
Sent: Friday, December 9, 2022 10:50 PM
To: Shraddha Hegde <shrad...@juniper.net>
Cc: Xiejingrong (Jingrong) <xiejingrong=40huawei....@dmarc.ietf.org>; James 
Guichard <james.n.guich...@futurewei.com>; SPRING WG <spring@ietf.org>; 
spring-cha...@ietf.org
Subject: Re: [spring] WGLC for draft-ietf-spring-sr-replication-segment

[External Email. Be cautious of content]

Shraddha,

As I clarified to Jingron in an earlier email in this thread, this restriction 
applies to Replication nodes, not to intermediate nodes on the paths between 
upstream and downstream replication nodes.
<SH> I did see your response earlier and I am not convinced with the reasoning 
and hence reiterating

Even if two replication nodes in an Anycast set or PeerSet have the same 
Replication SID, a packet sent to them using Anycast SID or PeerSet will be 
delivered to only one of these nodes.
<SH> Yes the packet is delivered to only one node not to both of them. The 
reason the controller included Anycast SID in segment list is for redundancy . 
The actual multicast tree really needs only one of these two nodes to replicate.


Pls see example below

[cid:image002.png@01D90C24.C49E87A0]
The segment list consists of anycast-SID for 5 and 6 and a replication SID. The 
actual multicast tree doesn't require traffic to go to 5 and 6 but it requires 
traffic to go to only one of them. Use of anycast SID is for redundancy in case 
of failure.

We will update the text in the next revision to specify the restriction only 
applies to the downstream nodes.
<SH> I really don't understand what you mean by this. I am expecting you to 
remove the MUST NOT restriction.
If you don't agree, would be good if you can provide example where the 
restriction makes sense.

-Rishabh

On Fri, Dec 9, 2022 at 4:29 AM Shraddha Hegde 
<shrad...@juniper.net<mailto:shrad...@juniper.net>> wrote:
Authors,

I have below comment on the draft.

1.
An Anycast SID or BGP PeerSID MUST NOT appear in segment
   list preceding a Replication SID.

The replication SIDs are similar to Binding-SIDs and Binding-SIds do not have 
any
such limitation. If there is an anycast SID before Replication SID,
The two anycast nodes should have same replication SID for the <Replication-ID, 
root-id>
pair. Intelligent controllers may be able to achieve this. The "MUST NOT" 
restriction
seems unnecessary.

2. BGP PeerSID MUST NOT appear in segment list
   preceding a Replication SID

   I understand this is meant to be PeerSet SID.
   These kind of restrictions don't seem necessary.
   If a multicast tree need to be built across multiple domains
   then it may use BGP PeerSetSID for the inter-domain link as long as the same 
replication SID is used
on the nodes which correspond to the PeerSetSID.

Rgds
Shraddha


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