Liaison statement
Response to WBA Liaison Statement on 5G & Wi-Fi RAN Convergence

State Posted
Submitted Date 2021-06-03
From Group tsvwg
From Contact David Black
To Group WBA
To Contacts WBA PMO
CcMartin Duke
Transport Area Working Group Discussion List
Gorry Fairhurst
Wesley Eddy
Zaheduzzaman Sarker
Response Contact Gorry Fairhurst
David Black
Wesley Eddy
Technical Contact David Black
Purpose In response
Attachments (None)
Liaisons referred by this one Liaison Statement on 5G & Wi-Fi RAN Convergence to IETF
Body
The IETF Transport Area Working Group (TSVWG) acknowledges the Wireless
Broadband Alliance (WBA) Liaison Statement on 5G & Wi-Fi RAN Convergence
(December 8, 2020) and thanks the WBA for their input.  The TSVWG chairs are
pleased to provide this liaison response on behalf of the TSVWG working group
and the IETF.

The TSVWG working group supports the WBA's objectives for differentiated QoS
across WiFi and 5G as described in the liaison communication, although the
scope of draft-henry-tsvwg-diffserv-to-qci appears to be significantly broader
than is necessary to achieve those objectives.  That breadth has led to
technical concerns in the IETF, particularly around the large number of
diffserv codepoints (DSCPs) used, as DSCPs are a severely limited resource.  In
addition, during TSVWG discussion of that draft, 3GPP clearly communicated
objections to the IETF standardizing mappings of DSCPs to QCIs and/or 5QIs for
use in public mobile networks.  We hope that the WBA appreciates the IETF's
reluctance to standardize mappings of DSCPs to QCIs and/or 5QIs in the presence
of clearly stated 3GPP opposition to use of those mappings in public mobile
networks.

We suggest a narrower approach that should have a better likelihood of success,
consisting of the following three steps based on the WiFi user priority to DSCP
mappings that the IETF has already standardized in RFC 8325 (Mapping Diffserv
to IEEE 802.11):
        i) Starting from the RFC 8325 mappings, identify a small set of
        existing DSCPs to initially focus on for use across WiFi and 5G
        networks. ii) Revise or replace draft-henry-tsvwg-diffserv-to-qci so
        that the resulting draft maps only that small set of DSCPs to QCIs
        and/or 5QIs. iii) Obtain 3GPP support for the resulting draft.

The TSVWG working group would definitely be interested in considering such a
draft for RFC standardization if that draft were accompanied by a supporting
3GPP liaison communication.

Sincerely,
David Black (TSVWG co-chair)