Liaison statement
Reply LS on 3GPP Work on Explicit Congestion Notification for Lower Layer Protocols

1. Overall Description:
IETF tsvwg requested information from 3GPP.
1) to tell the IETF tsvwg which 3GPP working groups could be affected by this
work. The working groups that could be affected by ongoing work on ECN include
SA2, SA4, RAN2, CT1, CT3,  and CT4. 2) To inform the IETF tsvwg of any specific
3GPP specifications affected by this work. The following Technical
Specifications either include a normative citation or normative text relying up
RFC 3168.

Working Group           Technical Specification
3GPP TSG SA WG2 23.060, 23.228, 23.401
3GPP TSG SA WG4 26.114, 26.223, 26.247
3GPP TSG CT WG1 24.229
3GPP TSG CT WG3 29.162, 29.163, 29.213, 29.292
3GPP TSG CT WG4 23.333, 29.333 (Iq stage 2 and stage 3), 23.334, 29.334 (Mp
stage 2 and    stage3), 29.238 (Ix stage 3), 29.332 (Mn stage 3), 29.232 (Mc
stage 3) 3GPP TSG RAN WG2        36.300 3GPP TSG RAN WG3        25.401

26.114, 29.162, 29.232, 29.238, 29.332, 29.333, 29.334 contain normative text
concerning the use of ECN in the 3GPP system. All of the listed specifications
contain references to other specifications concerning ECN support.

3) to forward this liaison statement to these affected working groups, and to
invite them to review the latest draft of the guidelines, available here:
         < http://tools.ietf.org/html/draft-ietf-tsvwg-ecn-encap-guidelines>

The usage of adding ECN to 3GPP protocols encapsulating or based on IP has not
been studied by 3GPP Working Groups. Therefore, no specific review comments on
the IETF tsvwg documents are provided at this time.

References to IETF RFC 3168, RFC 6679 (and related ECN specifications) were
added to 3GPP specifications from Release 10 onwards. Furthermore, numerous
3GPP specifications refer and employ TCP, UDP and other IP-based protocols.
Therefore, TSG SA requests IETF to kindly keep TSG SA informed of any changes
to ECN functionality (e.g. per IETF RFC 3168, RFC 6679 etc), along with changes
to various IP-based protocols such as TCP as a result of the ECN work of IETF
tsvwg.

2. Actions:
To RAN2, RAN3, SA2, SA4, CT1, CT3 and CT4 groups.
ACTION:         SA requests that if RAN2, RAN3, SA2, SA4, CT1, CT3 and CT4 have
further comments to IETF tsvwg documents that these comments be sent also to
SA, along with the WGs listed in CC, for the purposes of coordinating the
discussion. To IETF tsvwg: ACTION:         SA kindly requests IETF tsvwg to
take the information contained in this LS into account. Further, TSG SA
requests IETF to kindly keep TSG SA and affected WGs informed of any changes to
ECN functionality (e.g. per IETF RFC 3168, RFC 6679 etc), along with changes to
various IP-based protocols such as TCP as a result of the ECN work of IETF
tsvwg.

3. Date of Next TSG SA Meetings:
TSG SA #71      9 - 11 Mar 2016 Goteborg, Sweden
TSG SA #72      15 - 17 Jun 2016        South Korea