[spring] Re: Follow up "SID as source" in CE-CE ICMP case(uniform mode)

[linchangwang <[e-mail]>]

Hi Zafar,


As a co-author, thank you for your valuable feedback and detailed response.

We will update it in the next version by adding ICMP error handling.
Yes, the handling of ICMP errors may be correctly processed at the ingress PE, as detailed in Section 4.1.1 of RFC 8986.

Thank you again.

Thanks,
Changwang

发件人: Zafar Ali (zali) <zali=[e-mail]>
发送时间: 2026年4月2日 13:13
收件人: [e-mail]; 'Zafar Ali (zali)' <zali=[e-mail]>
抄送: 'SPRING WG' <[e-mail]>; [e-mail]; Zafar Ali (zali) <[e-mail]>
主题: [spring] Re: Follow up "SID as source" in CE-CE ICMP case(uniform mode)


Hi Feng

What I meant is that you need to explain in your draft how the source node (which uses a VPN SID as the source address) handles the ICMP error encountered by the data traffic (e.g., MTU exceeded).
Given the SID pseudo codes covers the upper layer processing, I think it should be fine.
But please document it in your draft.

Thanks
Regards … Zafar
From: [e-mail]<mailto:[e-mail]> <[e-mail]<mailto:[e-mail]>>
Date: Wednesday, April 1, 2026 at 11:46 PM
To: 'Zafar Ali (zali)' <zali=[e-mail]<mailto:zali=[e-mail]>>
Cc: 'SPRING WG' <[e-mail]<mailto:[e-mail]>>, [e-mail]<mailto:[e-mail]> <[e-mail]<mailto:[e-mail]>>, Zafar Ali (zali) <[e-mail]<mailto:[e-mail]>>
Subject: 回复: [spring] Re: Follow up "SID as source" in CE-CE ICMP case(uniform mode)
Hi Zafar,

Thanks for your response. In my opinion, the SRv6 compatible with firewall is orthogonal with the ICMP handling.

The source SRv6 node will receive ICMP (not encaped by SRv6 header) if the TTL gets expired in the network. There are 2 relevant cases in my head.
·         Case1: trace route from CE in uniform mode.  I did not give proposal.
·         Case2: Srv6 ping on PE. I gave proposal using VPN SID.

If you want have some proposals in the draft. I would say there are 2 existing proposals regarding ICMP handling. Proposal 1 is P node set the VPN SID as ICMP destination address (draft-varhal-6man-icmp-srv6-vpn). Proposal 2 is MPLS style, which forwarding to egress PE(draft-ali-6man-srv6-vpn-icmp-error-handling).

Since my draft is to address the firewall issue, I would say handling of ICMP should consider firewall case. To be more clear, the expected ICMP address pair would be a pair of VPN SID. Thus it will not only matter of ingress node, but will also relevant with P and egress PE.

BR,
Feng

发件人: Zafar Ali (zali) <zali=[e-mail]<mailto:zali=[e-mail]>>
发送时间: 2026年4月2日 8:51
收件人: [e-mail]<mailto:[e-mail]>
抄送: 'SPRING WG' <[e-mail]<mailto:[e-mail]>>; [e-mail]<mailto:[e-mail]>; Zafar Ali (zali) <[e-mail]<mailto:[e-mail]>>
主题: [spring] Re: Follow up "SID as source" in CE-CE ICMP case(uniform mode)

Hi Feng

My comments have nothing to do with the CE-CE trace route in uniform mode proposal in 6man.
You need to explain how the source node processes the ICMP error if it receives it from the network.
You cannot exclude ICMP error handling from your proposal.

Hope it helps.

Thanks
Regards … Zafar
From: [e-mail]<mailto:[e-mail]> <[e-mail]<mailto:[e-mail]>>
Date: Thursday, March 26, 2026 at 2:18 AM
To: Zafar Ali (zali) <[e-mail]<mailto:[e-mail]>>
Cc: 'SPRING WG' <[e-mail]<mailto:[e-mail]>>, [e-mail]<mailto:[e-mail]> <[e-mail]<mailto:[e-mail]>>
Subject: Follow up "SID as source" in CE-CE ICMP case(uniform mode)
Hi Zafar,

Thanks for your comments on SPRING meeting last week. You mentioned the CE-CE ICMP issue with uniform mode in provider network, and there are some proposals in 6man.

Here comes my proposal:
I would exclude that scenario in the scope of “draft-yang-spring-sid-as-source-address”. Will that be an acceptable solution for you?

BR,
Feng Yang
China Mobile Research Institute

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