This helps, thank you.

A ULA is not necessarily non-routable, though.  Would it be possible to use
the RFC 6666 discard prefix?

On Thu, Oct 16, 2025 at 9:48 PM Rishabh Parekh <[email protected]> wrote:

> Erik,
>
> Reply inline @ [RP]
>
> On Thu, Oct 16, 2025 at 8:55 PM Erik Kline via Datatracker <
> [email protected]> wrote:
>
>> Erik Kline has entered the following ballot position for
>> draft-ietf-bess-mvpn-evpn-sr-p2mp-15: Discuss
>>
>> When responding, please keep the subject line intact and reply to all
>> email addresses included in the To and CC lines. (Feel free to cut this
>> introductory paragraph, however.)
>>
>>
>> Please refer to
>> https://www.ietf.org/about/groups/iesg/statements/handling-ballot-positions/
>> for more information about how to handle DISCUSS and COMMENT positions.
>>
>>
>> The document, along with other ballot positions, can be found here:
>> https://datatracker.ietf.org/doc/draft-ietf-bess-mvpn-evpn-sr-p2mp/
>>
>>
>>
>> ----------------------------------------------------------------------
>> DISCUSS:
>> ----------------------------------------------------------------------
>>
>> # Internet AD comments for draft-ietf-bess-mvpn-evpn-sr-p2mp-15
>> CC @ekline
>>
>> * comment syntax:
>>   - https://github.com/mnot/ietf-comments/blob/main/format.md
>>
>> * "Handling Ballot Positions":
>>   -
>> https://ietf.org/about/groups/iesg/statements/handling-ballot-positions/
>>
>> ## Discuss
>>
>> ### S3.1.2
>>
>> * "The advertising ingress PE MAY
>>    use a non-routable prefix as LOC of the SRv6 Multicast Service SID to
>>    prevent packets being routed to it based on the SID."
>>
>>   Can you clarify what is intended here?  I'm afraid I couldn't figure out
>>   what is meant by a non-routable prefix to prevent packets being routed
>>   to the advertising router.
>>
>>   Possibly I just don't have the right mental model yet.  Is this for some
>>   scenario where discarding traffic is desired?
>>
>>
>>
> [RP] The use-case is when an SRv6 P2MP tree is shared across two or more
> MVPN contexts. In this case, the ingress PE advertises an upstream-assigned
> SID (one of End.DTMC4/6 specified in Section 5.21) to identify specific
> MVPN context for payload processing at an egress PE (which receives MVPN
> customer payload on the shared SRv6 P2MP tree). This upstream assigned SID
> is carried in SRH of an IPv6 encapsulated packet from the ingress PE. On
> the egress PE, this SID (or specifically FUNCT portion of the SID) should
> just be used to derive the MVPN context. If an egress PE mistakenly uses
> this SID to forward the packet (by setting it in the IPv6 DA header), the
> packet will incorrectly routed back to the ingress PE if the LOC portion of
> the SID identifies the ingress PE. To prevent incorrect re-routing using
> the SID, the ingress PE may use a non-routable IPv6 prefix (such as Unique
> Local Address prefix) as the LOC portion of End.DTMC4/6 SID.
>
> I hope this answers your question.
>
>
>>
>>
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