[DMM] Re: SRv6 replacement of GTP-U for 6G - Planned proposa l for a 3GPP study

Bill

RFC 9433 details how the RAN portions can be encoded in SRv6 SIDs.  There was also a hackathon at IETF 122 where BGP support was added for the new NLRIs.  GoBGP v 3.36 has full support for SRv6-MUP in this mode.

In both these cases, GTP is retained on N3 but I believe that it could be interesting to see how N3 could move to a pure SRv6 implementation and remove GTP in it’s entirety.

At present, the domain of a gNB is limited to the scope of the GTP.  Having a gNB support multiple PLMNs, each mapped to a different SRv6 SID or even within a QCI to different SIDs without having to deal with GTP could have great applicability to wholesale networks (those that support MVNOs).   Removing SRv6 would also remove the UDP + GTP header in each packet.

David

From: DanVoyer <[email protected]>
Date: Wednesday, 6 August 2025 at 15:11
To: Bill Gage <[email protected]>
Cc: [email protected] <[email protected]>
Subject: [DMM] Re: SRv6 replacement of GTP-U for 6G - Planned proposal for a 3GPP study

Hi Bill,

One of the values for SRv6, compared to GTP, is it's stateless. But, the goal for Marcus is open a study at 3GPP to come up with a comparable analysis for U-GTP and SRv6.

On your point for RAN-related information, I'll invite you to read the document TR. 29.892 section 6.2
6.2.2: Details how SRv6 can be applied within 5GC, including protocol adaptation to the N3/N9/N6 interfaces and mapping from GTP attributes (e.g., QFI, TEID) to SIDs.

Thanks,
Dan

On Thu, Jul 31, 2025 at 12:03 PM Bill Gage <[email protected]<mailto:[email protected]>> wrote:
Hello Markus -

I'm a bit confused by your proposal.

As indicated in the slide set, slides 1-7, SRv6 makes sense as a TE
replacement for MPLS in the user plane. But I don't see how SRv6 (at
least in its current form) provides value as a replacement for GTP-U.

In addition to the PDU (IP packet) being transported, GTP-U includes a
header that contains RAN-related information fields such as end point
identifier (for mapping to a radio bearer), sequence numbers, QoS
information, etc.

What value is SRv6 bringing to this capability?

/bill

On 2025-07-21 12:33 p.m., [email protected]<mailto:[email protected]> wrote:
> Dear DMM and SRv6ops community,
>
> I would like to draw your attention to an activity that we want to bring
> to 3GPP to investigate for 6G. It is about the replacement of GTP-U by
> SRv6 for mobile user plane. This should be of particular interest to all
> operators/vendors already using/implementing SRv6 or planning its
> introduction.
>
> The last three slides in the slide set at https://datatracker.ietf.org/
> meeting/123/materials/slides-123-srv6ops-21-advancing-deutsche-telekoms-
> traffic-engineering-for-srv6-01 <https://datatracker.ietf.org/
> meeting/123/materials/slides-123-srv6ops-21-advancing-deutsche-telekoms-
> traffic-engineering-for-srv6-01> provide more information about our
> motivation and will be presented by me tomorrow during srv6ops session.
>
> Please read them, attend tomorrow's SRv6ops session or contact me or
> Maria if you are interested.
>
> We are particularly interested in expanding our round of supporters in
> 3GPP, getting an assessment from you that you may have already done on
> this topic and studying with you if 3GPP agrees.
>
> Br
>
> Markus
>

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