Hi Sasha,

Indeed, it is as you stated. If the IPv6 packed has inner IPv4/IPv6 header - 
the procedure described in draft-ali-6man-srv6-vpn-icmp-error-handling is 
triggered. If the IPv6 packed has no inner IPv4/IPv6 header - current procedure 
defined in [RFC4443], Section 3.3, and [RFC2473], Section 8 is used.

Moreover, in case of multiple IP encapsulations (for example original SRv6 
IP-VPN packet is forwarded across backup TI-LFA path in H.encap mode, which 
pushes additional IPv6 encap), the procedure applies to most inner IPv4/IPv6 
header.


We might clarify this in the updated text of the draft.


Regards,
Krzysztof



--
Krzysztof Grzegorz Szarkowicz
PLM, Solutions Architect
Networking, Routing Infrastructure Solutions
[email protected]
+49 89 203 012 127

Hewlett Packard Enterprise
HPE.com

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On 2026 Jul 22, at 10:36, Zafar Ali (zali) <[email protected]> 
wrote:

Hi Sasha

Many thanks for your comments and follow up.
Yes, you are right and I also answered along these lines.
Authors will be happy to add a clarification.

Thanks

Regards … Zafar

From: Alexander Vainshtein <[email protected]>
Date: Wednesday, July 22, 2026 at 4:33 AM
To: [email protected] 
<[email protected]>
Cc: [email protected] <[email protected]>
Subject: [spring] My question about draft-ali-6man-srv6-vpn-icmp-error-handling 
at the mike today

Hi all,
I have asked at he mike today how can the P router that detects a problem that 
triggers generation of the ICMP Error message differentiate between 
SRv6-encapsulated packets belonging to an IP-VPN service (and so could be 
tunneled to the egress PE for handling) and that belong to an EVPN service (so 
that tunneling them to the egress PE would be useless?

Such differentiation would be problematic in the case of services running on an 
IP/MPLS underlay, especially if EVPN service were not using the CW in the 
encapsulation.

Once I came back to my place, I understood that in the case of SRv6 undelay 
such a differentiation would be trivial: the P router that detects a problem 
could simply check the next header value at the end of the SRv6 encapsulation: 
IPv4 and IPv6 would indicate an IP-VPN service, while Ethernet would indicate 
an EVPN service.

I am not sure this is explicitly stated in the draft, but is trivial enough.

Regards,
Sasha




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