Re: [spring] [DMM] How Encoded SID should be placed in SL (SRv6-mobile-uplane)

[Satoru Matsushima <[e-mail]>]

Hi Kentaro,


On Mon, Aug 28, 2017 at 11:52 PM, Kentaro Ebisawa <[e-mail]>
wrote:

> Hi,
>
> I have a few questions about how Encoded SID should be placed in Segment
> List and IPv6 Dst Address in Mobile User-Plane use case.
>
> # Refering to draft-matsushima-spring-dmm-srv6-mobile-uplane-01.
> # I tried to check Slides from IETF 99 but link seems to be missing.
> # https://datatracker.ietf.org/doc/slides-99-dmm-srv6-for-mobi
> le-user-plane/


That looks weird. It's not only for that document.
All ietf99 meeting materials are mis-linked from "
https://datatracker.ietf.org/meeting/99/agenda" page.



>
> Q1) Up Link packet (existing network to SRv6)
>
> > outer IPv4 and tunnel header. And then the endpoint does T.Insert
> > process with the SID which consists of the allocated domain-wise SID
> > prefix, source and destination addresses, and tunnel identifier as
> > described in Figure 3. Then the endpoint send out the packet to the
> > SRv6 network along with its routing policy.
>


In above text, we assumed that the payload encapsulated in the IPv4 tunnel
is an IPv6 packet.
So the source address of the packet should be an MN's address.


> How would IPv6 src/dst addr and Segment List look like for this Up Link
> packet? (existing network to SRv6)
> My understanding is usually source address of the T.Insert node is not
> included in Segment List.
> But from above description, it looks like you intend to require Encoded
> SID (Fig 3) to be included in the Segment List of UL packet.
>
> For example, is below packet structure what you intended in case you have
> n segments to traverse in SRv6 nework?
>
> IPv6 Src: Encoded SID or T.Insert node ??
> IPv6 Dst: SL[n]
> Segment Left = n
> SL[0] = Segment 0
> SL[n] = Segment n
> SL[n+1] = Encoded SID
>
>
SL[0] must be original destination address of the IPv6 packet which the MN
sends out.
The SID which consists of the existing network tunnel info would be placed
at SL[1]. In case of that it means that the endpoint which the SID
indicates is egress of the SRv6 domain. If any other endpoints exist in the
segment list, that SID would be placed at SL[n] where n >=2.



> Q2) Down Link packet (SRv6 to existing network)
>
> > When the endpoint receives packet and the active segment of the
> > packet indicates the SID, the endpoint pop the SRH of the SID, and
>
> On the other hand, are there any reason that description in page 7 does
> not mandate m to be zero while requiring to pop the SRH?
>

As similar with UL, SL[0] must be original destination address. In DL
direction the interworking node must be egress of the SRv6 domain so that
the tunnel info encoded SID should be placed in SL[1].

Best regards,
--satoru



> My understanding of DL packet (SRv6 to existing network) is as below.
>
> IPv6 Src: Origin Host
> IPv6 Dst: SL[n]
> Segment Left = n
> SL[m] = Encoded SID
> SL[m+1] = Segment m+1
> SL[n] = Segment n
>
>
> Regards,
> --
> Ponto Networks, Inc.
> Kentaro Ebisawa <[e-mail]>
>
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