Liaison statement
Response to IETF liaison: ‘Potential RTGWG work related to the disaggregated BNG architecture’

Dear colleagues,

Thank you for your 3 December 2018 liaison ‘Potential RTGWG work related to the
disaggregated BNG architecture’ regarding the IETF RTGWG work on a set of proposals for
protocols to realize the separation of the control and user plane for the disaggregated BNG
architecture for fixed network subscribers.

In response to your request for feedback and further dialog, we would like to provide you initial
feedback based on conversations on this topic during our recent 4Q2018 meeting. In addition,
we plan to review and provide comments to you on the following individual drafts for control and
user plane separation for disaggregated BNGs:

Requirements:
• draft-cuspdt-rtgwg-cusp-requirements-03
• draft-wadhwa-rtgwg-bng-cups-protocol-requirements-01

Architecture:
• draft-cuspdt-rtgwg-cu-separation-bng-architecture-03
• draft-wadhwa-rtgwg-bng-cups-02

During our 4Q2018 meeting we discussed our current work for Cloud Central Office (CloudCO)
and Wireline and Wireless Convergence (WWC) as it relates to the need for new protocols for
the separation of the control and user plane for disaggregated BNGs for fixed network
subscribers.

In the context of WWC our current state of 5G Fixed Mobile Convergence (FMC) work with
respect to Control and User Plane Separation (CUPS) is that our preferred direction would be
for the BBF to specify extensions to 3GPP's PFCP protocol (TS 29.244). We have already
started a project that will verify this preferred direction.

In the context of our CloudCO work, we would like to inform you of the following:

• The TR-384 Cloud Central Office Reference Architectural Framework technical report is a
framework document where multiple deployment options are possible and the BBF
doesn’t mandate a particular deployment. As such the deployment option for the
separation of the control and user plane described in section 5.2.5 Decomposition of the
BNG is one of a number of possible deployment options.

• With respect to the separation of the control and user plane for disaggregated BNGs, the
BBF has not identified the need or requirements at this time for a new protocol based on
known use cases that are documented in our Application Notes.

• We would like to inform you that as our Application Note related to the Converged Coreas-
a-Service (with PNF based User Plane), the BBF is starting work in that context on
the disaggregated BNG.

With respect to the review of the individual drafts mentioned previously we intend to complete
the review of the drafts and communicate any comments to you by mid-February 2019.

As stated in your liaison request we would welcome further coordination as the work of both
organizations progresses on this topic. While the BBF is working on the on-going activities
(verification of the PFCP protocol for 5G FMC, disaggregated BNG) communicated in this
liaison, we would like to state that we do not object to the IETF continuing work in parallel on a
protocol for the separation of the control and user plane.

Sincerely,

Lincoln Lavoie,
Broadband Forum Technical Committee Chair