Re: New Liaison Statement, "LS on indicating service continuity usage of the additional IPv6 prefix in Router Advertisement"

["Sri Gundavelli (sgundave)" <[e-mail]>]

Dear 3GPP SA2 Chair:

Thank you for your LS query (Reference:
https://datatracker.ietf.org/liaison/1554/). The IETF DMM working group
has reviewed the LS statement and below is our response based on the
discussions in the WG and feedback.



In our view, the work-item described in the LS query has three components:


1.) The approach of coloring IPv4 and IPv6 addresses/prefixes with
mobility properties.

This is about standardizing IP address address/prefix ³types". Each ³type"
has a certain behavior that the network is expected to provide. Section
3.1, of draft-ietf-dmm-ondemand-mobility-13 defines the following four
address types, which are applicable to both IPv4 and IPv6 addresses and
prefixes. 

#a. Fixed IP Address
#b. Session-lasting IP Address
#c. Non-persistent IP Address
#d. Graceful Replacement IP Address


These modes, #a, #b, #c,and #d can be mapped to the 3GPP SSC modes 1, 2
and 3.

We are happy to report that this work-item is on track to become an
³informational standard", and will most likely will hit IESG very soon.



We request 3GPP to provide any feedback that you may have on this
draft.




2.) The approach of network including property meta-data in address
assignment procedures

There are multiple mechanisms for address configuration delivery to the
end-host:

#a.) DHCPv4
#b.) DHCPv6
#c.) IPv6 ND (PIO Options, others ..etc)
#d.) IKEv2 Address Configuration Options


There are many proposals on this including:

https://www.ietf.org/id/draft-feng-dmm-ra-prefixtype-01.txt
https://www.ietf.org/id/draft-moses-dmm-dhcp-ondemand-mobility-08.txt

Also, some proposals from the previous years, which may be related:

https://www.ietf.org/archive/id/draft-ietf-mif-mpvd-ndp-support-03.txt
https://www.ietf.org/archive/id/draft-ietf-mif-mpvd-id-02.txt
https://www.ietf.org/archive/id/draft-bhandari-dhc-class-based-prefix-05.tx
t
https://tools.ietf.org/html/draft-kaiser-nd-pd-01

...


Currently, some of these documents are under review in the IETF DMM WG.
However,
the DMM working group has not chosen any specific draft as WG document.
Given the interest from 3GPP for this work, we will try to accelerate the
document selection process and will try to move this work forward. This is
subject to finding consensus for taking up this work, and the charter
allowing
this to be in DMM scope.


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.




3.) The approach of indicating the coloring meta-data to the applications
on the mobile node (UE in 3GPP terminology).

This is about extending socket interface with the property tags. This is
covered in draft-ietf-dmm-ondemand-mobility-13,

We are happy to report that this work is on track to become an
³informational standard", and will most likely will hit IESG very soon.


We kindly request 3GPP to provide any feedback that you may have on this
draft.




Regards
Dapeng Liu and Sri Gundavelli
(Chairs IETF DMM Working Group)








On 1/16/18, 2:45 PM, "Liaison Statement Management Tool" <[e-mail]>
wrote:

>Title: LS on indicating service continuity usage of the additional IPv6
>prefix in Router Advertisement
>Submission Date: 2018-01-16
>URL of the IETF Web page: https://datatracker.ietf.org/liaison/1554/
>
>From: Chang hong <[e-mail]>
>To: Sri Gundavelli <[e-mail]>,Dapeng Liu
><[e-mail]>,Terry Manderson <[e-mail]>,Suresh
>Krishnan <[e-mail]>,Robert Hinden <[e-mail]>,Ole
>Troan <[e-mail]>
>Cc: Dapeng Liu <[e-mail]>,Terry Manderson
><[e-mail]>,IPv6 Maintenance Discussion List
><[e-mail]>,Ole Troan <[e-mail]>,Sri Gundavelli
><[e-mail]>,The IETF Chair <[e-mail]>,Robert Hinden
><[e-mail]>,Distributed Mobility Management Discussion List
><[e-mail]>,Suresh Krishnan <[e-mail]>
>Response Contacts: [e-mail],[e-mail]
>Technical Contacts:
>Purpose: For information
>
>Body: 1. Overall Description:
>3GPP working group SA2 (System Architecture) would like to inform the
>IETF that SA2 has defined three SSC (Session and Service Continuity)
>modes in 3GPP TS 23.501 ("Architecture for the 5G System") clause 5.6.9
>as follows:
>-	With SSC mode 1, the network preserves the connectivity service
>provided to the UE. For the case of PDU Session of IPv4 or IPv6 type, the
>IP address is preserved.
>-	With SSC mode 2, the network may release the connectivity service
>delivered to the UE and release the corresponding PDU Session. For the
>case of IPv4 or IPv6 type, the network may release IP address(es) that
>had been allocated to the UE.
>-	With SSC mode 3, changes to the user plane can be visible to the UE,
>while the network ensures that the UE suffers no loss of connectivity. A
>connection through new PDU Session Anchor point is established before the
>previous connection is terminated in order to allow for better service
>continuity. For the case of IPv4 or IPv6 type, the IP address is not
>preserved in this mode when the PDU Session Anchor changes.
>SA2 has also adopted the use of IPv6 multi-homing in a PDU Session
>(referred to as "multi-homed IPv6 PDU Session") as described in 3GPP TS
>23.501 clause 5.6.4.3, a PDU Session being an association between the UE
>and a Data Network that provides a data connectivity service, which is
>also defined in 3GPP TS 23.501.
>When a new IPv6 Prefix is assigned to the UE for a multi-homed IPv6 PDU
>Session, SA2 has decided to use the Router Advertisement message
>according to IETF RFC 4191 to deliver the new IPv6 prefix to the UE and
>configure the Routing Rules in the UE by using the Route Information
>Option. 
>SA2 is looking for a mechanism to deliver information regarding the
>service continuity usage (e.g. whether the prefix can be replaced with or
>without grace period) associated with the new IPv6 prefix to the UE via
>the 5G System user plane.
>
>SA2 understands that the IETF draft "draft-ietf-dmm-ondemand-mobility-12"
>defines four IP address types that can be mapped to the three SSC modes
>as follows:
>
>-	SSC mode 1 corresponds to either FIXED or SESSION_LASTING;
>-	SSC mode 2 corresponds to NON_PERSISTENT;
>-	SSC mode 3 corresponds to GRACEFUL_REPLACEMENT.
>
>SA2 would like to understand if there is any IETF work related to
>delivery of the IP address type (according to IETF draft
>"draft-ietf-dmm-ondemand-mobility-12") in the Router Advertisement
>message, which could be used for delivery of the service continuity usage
>associated with a new IPv6 prefix in a multi-homed IPv6 PDU Session.
>
>2. Actions:
>To IETF Internet Area, DMM, 6MAN:
>ACTION: 	SA2 respectfully asks IETF Internet Area, DMM and 6MAN to
>provide feedback on any IETF work related to delivery of IP address type
>(according to IETF draft "draft-ietf-dmm-ondemand-mobility-12") in the
>Router Advertisement message.
>
>3. Date of Next SA2 Meetings:
> 3GPPSA2#125  OR 22 - 26 Jan 2018    Gothenburg  	SE
> 3GPPSA2#126  OR 26 Feb - 2 Mar 2018    US	        US
>Attachments:
>
>    S2-179625_e-mail_rev2_S2-179363_LS_out_to_IETF_Internet_Area_DMM_6MAN
>    
>https://www.ietf.org/lib/dt/documents/LIAISON/liaison-2018-01-16-3gpp-tsgs
>a-sa2-int-6man-dmm-ls-on-indicating-service-continuity-usage-of-the-additi
>onal-ipv6-prefix-in-router-advertisement-attachment-1.doc
>