Hi Alex,

As you know, I have written a draft that defines an extension to DHCPv6 for 
supporting OnDemand values (also for SSC modes - Service and Session 
Continuity) with prefix delegation. I discussed that with SA2 people and they 
are aware of that possibility. Currently, SA2 prefer the RA mobility extension 
and there was not enough support in the dmm WG for the DHCPv6 option. 

So, unfortunately I do not think we should advocate for an approach that is not 
supported by us (dmm).

Please also note that SSC modes is part of release 15. Please refer to TS 
23.501 and TS 23.502 for more technical details. Stage 2 of release 15 has been 
finalized in December 2017 and Stage 3 is scheduled for the summer of 2018 (I 
do not remember the exact date).

Unfortunately, we (IETF) are often too late in providing specifications in time 
for 3GPP releases. This is partially due to our tendency to drag our work (in 
my opinion). Just see how long the OnDemand work is taking us. Here we have a 
chance to provide a specification that will be gladly adopted by the Cellular 
world. If not in release 15, at least in release 16.

Let's meet the challenge and prove to ourselves that we can be useful in this 
case.

By the way, my personal view is that we should provide the extensions to both 
RA and DHCPv6. I accept that due to the fact that SA2 prefers RA, we should 
give it a higher priority.

Regards,
Danny   

-----Original Message-----
From: dmm [mailto:[email protected]] On Behalf Of Alexandre Petrescu
Sent: Friday, March 23, 2018 09:48
To: [email protected]
Subject: Re: [DMM] New Liaison Statement, "LS on indicating service continuity 
usage of the additional IPv6 prefix in Router Advertisement"



Le 22/03/2018 à 18:49, Liaison Statement Management Tool a écrit :
[...]

> SA2 would like to point out that among the four mechanisms for address 
> configuration delivery mentioned in your LS reply (i.e.
> DHCPv4, DHCPv6, IPv6 ND and IKEv2) only the IPv6 ND mechanisms, and in 
> particular the Router Advertisement message, seem to be applicable in 
> the 5G System architecture in the specific context of Multi-homed
> IPv6 PDU Sessions.
Please tell SA2 that current 4G cellular networks are specified to, and do use 
to some extent, DHCPv6 Prefix Delegation to assign a prefix to an end node like 
an IoT Router.

A /56 prefix delivered to the end node should have the same capabilities as an 
address. We also want that /56 prefix to be more stable, or less stable, etc.

I dont understand why 5G System architecture excludes DHCPv6 from the list of 
applicable address configuration delivery.

I understand why 5G System architectures prefers ND - it is for addresses.

Alex

> 
> 
> With respect to the following question in the IETF’s reply LS:
>                  We also like to point out that, all though the LS statement 
> explicitly refers to both IPv4 and IPv6 address types, however it only 
> mentions about (RA) (IPv6
>                  ND implied) as the mechanism for address property delivery. 
> It is to be noted that the approach of delivering coloring meta-data in RA 
> messages will most
>                  likely be to limited to IPv6 address/prefix types and will 
> not be extended to IPv4 addresses. If this capability is required for IPv4, 
> we may have to possibly
>                  extend DHCP protocol(s).
> 
>                  We request 3GPP to clarify if the Ask is explicitly for 
> IPv6, or if its for both IPv4 and IPv6 address/prefix types.
> 
> 
> SA2 would like to clarify that the request is explicitly for IPv6. SA2 
> discussed the example documents that were referenced in your LS reply and 
> concluded that the following draft seems to be the most promising candidate 
> for the problem under discussion in this correspondence: 
> https://www.ietf.org/id/draft-feng-dmm-ra-prefixtype-01.txt.
> SA2 would like to kindly ask IETF DMM working group to keep SA2 updated of 
> the work on the subject of including property meta-data in IPv6 ND address 
> assignment procedures for potential use in the 5G System to indicate the 
> mobility property of additional IPv6 prefixes assigned as part of the 
> Multi-homed IPv6 PDU Session functionality.
> 
> 
> 2     Actions
> To IETF DMM working group:
>      ACTION: SA2 would like to kindly ask IETF DMM working group to keep SA2 
> updated of the work on the subject of including property meta-data in IPv6 ND 
> address assignment procedures for potential use in the 5G System to indicate 
> the mobility property of additional IPv6 prefixes assigned as part of the 
> Multi-homed IPv6 PDU Session functionality.
> 
> 
> 3     Dates of next TSG SA WG2 meetings
> TSG SA WG2 Meeting 127        16 - 20 Apr 2018        Sanya, CN
> TSG SA WG2 Meeting 127-Bis    28 May – 1 Jun 2018     Newport Beach, US
> Attachments:
> 
>      S2-182967_was2844_LS_IETF_SSC3
>      
> https://www.ietf.org/lib/dt/documents/LIAISON/liaison-2018-03-22-3gpp-
> tsgsa-sa2-int-6man-dmm-ls-on-indicating-service-continuity-usage-of-th
> e-additional-ipv6-prefix-in-router-advertisement-attachment-1.docx
> 
> _______________________________________________
> dmm mailing list
> [email protected]
> https://www.ietf.org/mailman/listinfo/dmm
> 

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