Hi Rishabh & authors,

To close out this discussion, in sections 2.1 and 2.2 we have:
There MAY be SIDs after the Replication SID in the segment list of a packet. 
These SIDs are used to provide additional context for processing a packet 
locally at the node where the Replication SID is the Active Segment. The 
processing of SIDs following the Replication SID MUST NOT forward the SR-MPLS 
packet to another node.

The chairs believe it would be helpful to add a sentence to clarity the scope 
and offer the following text "Coordination regarding the absence or presence 
and value of context information for replication leaves is outside the scope of 
this document.".

Thanks!

Jim, Joel & Bruno


From: Rishabh Parekh <risha...@gmail.com>
Sent: Thursday, February 16, 2023 12:37 AM
To: James Guichard <james.n.guich...@futurewei.com>
Cc: Xiejingrong (Jingrong) <xiejingrong=40huawei....@dmarc.ietf.org>; 
bruno.decra...@orange.com; SPRING WG <spring@ietf.org>
Subject: Re: WGLC for draft-ietf-spring-sr-replication-segment

James,

On Wed, Feb 15, 2023 at 8:05 AM James Guichard 
<james.n.guich...@futurewei.com<mailto:james.n.guich...@futurewei.com>> wrote:
Hi Jingrong & document authors,

I would like for now to leave aside the issue of whether or not application/VPN 
specifics should be outside the scope of this SPRING document (I will however 
be revisiting this point in subsequent emails) and focus on bringing closure to 
the technical comments detailed in 
https://mailarchive.ietf.org/arch/msg/spring/_1sSZCfCZWlHwXvYpfOtDZZ9M3g/<https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fmailarchive.ietf.org%2Farch%2Fmsg%2Fspring%2F_1sSZCfCZWlHwXvYpfOtDZZ9M3g%2F&data=05%7C01%7Cjames.n.guichard%40futurewei.com%7Cdb56daac0d014f3482a208db0fdfde76%7C0fee8ff2a3b240189c753a1d5591fedc%7C1%7C0%7C638121226437340003%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=xMx%2BHL31Nq%2FdqZZOXZf9ZEkPD5dptGq7Tsdp7mwieiU%3D&reserved=0>.

As I read through your comments Jingrong I think I can summarize your objection 
to be that you believe the proposal breaks the SRv6 architecture as the 
forwarding relies upon local state rather than state carried within the SRH. Do 
I have that right? If this is the case then you need to be specific in terms of 
which text/sentences in the document are in conflict with which text/sentences 
of existing RFCs. As written I think Rishabh's forwarding example is accurate 
as he describes a lookup on the Replication SID and the action is to either 
update the outer IPv6 address with the downstream nodes address, or 
re-encapsulate the packet with a new IPv6 header and SRH. I might draw your 
attention to  
https://www.rfc-editor.org/rfc/rfc8754.html#name-fib-entry-is-a-locally-inst<https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.rfc-editor.org%2Frfc%2Frfc8754.html%23name-fib-entry-is-a-locally-inst&data=05%7C01%7Cjames.n.guichard%40futurewei.com%7Cdb56daac0d014f3482a208db0fdfde76%7C0fee8ff2a3b240189c753a1d5591fedc%7C1%7C0%7C638121226437340003%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=q56RV5lZ8B6B%2F43YzGfa1LyhHu3l1JZbK9M%2Byx3hDvk%3D&reserved=0>
 which talks about the definition of future SIDs and their behaviors.

Further your comments appear to me to suggest that the VPN identification 
encapsulated at PE1 acts like a normal VPN SID in the sense that forwarding is 
based upon that IPv6 address. I don't think that is the intent here; I think 
the SID is used as an identifier for the VPN itself so that the downstream 
nodes are given the correct VPN forwarding context i.e. they are not supposed 
to use that SID to forward the packets back to PE1. Perhaps the authors could 
clarify this point further?

Hi Rishabh, it would be helpful if you could review the comments in 
https://mailarchive.ietf.org/arch/msg/spring/_1sSZCfCZWlHwXvYpfOtDZZ9M3g/<https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fmailarchive.ietf.org%2Farch%2Fmsg%2Fspring%2F_1sSZCfCZWlHwXvYpfOtDZZ9M3g%2F&data=05%7C01%7Cjames.n.guichard%40futurewei.com%7Cdb56daac0d014f3482a208db0fdfde76%7C0fee8ff2a3b240189c753a1d5591fedc%7C1%7C0%7C638121226437340003%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=xMx%2BHL31Nq%2FdqZZOXZf9ZEkPD5dptGq7Tsdp7mwieiU%3D&reserved=0>
 again and perhaps provide more clarity on the expected behavior as there seems 
to be a difference in understanding of the actual operation.

[RP] Exactly, the only purpose of VPN SID is to provide a VPN context at 
Leaf/Bud nodes to forward the inner packet (encapsulated at ingress PE).  I 
have removed most of the text related to VPN (in yet unpublished next revision) 
based on Bruno's earlier, but this has been explained earlier in the thread.

-Rishabh


_______________________________________________
spring mailing list
spring@ietf.org
https://www.ietf.org/mailman/listinfo/spring

Reply via email to