Re: [bcause] [Bcause] interest and scope?

[Greg Mirsky <[e-mail]>]

Hi Martin, et al.,
I'd not discuss whether PFCP can be extended to suit yet undocumented DBNG
CUPS requirements without changes to its architecture. Many stated that
they believe that that is achievable and I'm not to argue with what people
believe or don't believe in. I just want to point out that we have heard
from several operators that they are interested only in FN (fixed network)
DBNG CUPS. I interpret that these operators have and want to keep their
fixed and mobile networks operated separately. And even though PFCP may be
already is familiar to the operations team that manages their mobile
network, introducing the new protocol into the operation of the fixed
network will increase their operational cost. More so, operators that are
not looking to introduce hybrid access or 5G FMC at any time soon may have
a preference on which protocol selection as that is the reflection of their
operational model. I don't think that requests by these operators should be
ignored and the answer given by SDOs include only PFCP-based DBNG CUPS.
I've participated in the discussion and contributed to the charter. The
charter intended to work on FN-only DBNG CUPS first and deliver results
quickly. Adding hybrid access and 5G FMC could be discussed later,
including, based on findings by experts at BBF.

Regards,
Greg

On Mon, Mar 4, 2019 at 2:22 PM Vigoureux, Martin (Nokia - FR/Paris-Saclay) <
[e-mail]> wrote:

> Hello,
>
> as you might know, the RTGWG has hosted, for some time now, a set of
> documents that relate to the separation of the user plane and control
> plane of Broadband Network Gateways.
> These documents can be found at
> https://datatracker.ietf.org/group/rtgwg/documents/ and start with
> draft-cuspdt-* or draft-wadhwa-*
>
> Please read them if you haven't already.
>
> Recently, a group of persons has worked together and produced few
> paragraphs in support of their willingness to see a working group on
> this topic formed.
>
> Considering this, I am sharing this text with the IETF community in
> order to evaluate
> * the wider interest in, and willingness to work on, this topic,
> * the appropriateness of creating a focussed and short-lived working
> group (as opposed to continuing in rtgwg).
> To that effect, please read and comment on the text further down, it is
> here for being debated.
> As a matter of clarification: me sharing it, instead of the authors
> doing it, does not carry any special meaning.
>
> Important note: this topic has its roots in BroadBand Forum (BBF) with
> which IETF has exchanged few liaisons on the topic recently. These are
> important reads:
> https://datatracker.ietf.org/liaison/1619/
> https://datatracker.ietf.org/liaison/1615/
> https://datatracker.ietf.org/liaison/1600/
> https://datatracker.ietf.org/liaison/1566/
>
>
> ---
> Current Broadband Network Gateways (BNGs) that terminate residential
> broadband subscribers at the edge of service provider networks run as an
> integrated system where both the subscriber management control plane and
> traffic forwarding user plane are combined in a single system. In a
> large network, where the subscriber density is high, it is better to
> distribute and locate BNG systems closer to the subscribers, especially
> when the content caches are distributed to reduce backhaul costs and
> latency. In this scenario, as the BNG footprint grows, the subscriber
> management control points also proliferate, increasing operational
> complexity. This trend motivates the broadband network access industry
> to adopt new architectures that take advantage of the increasing ability
> to disaggregate and virtualize appropriate network access functions.
> Additional benefits can be realized by separating subscriber management
> control plane (CP) and traffic forwarding user plane (UP) for BNGs
> (referred to as Control and User Plane Separation (CUPS)). That
> simplifies operations, provides independent location, and scaling for CP
> and UP functions. A single CP function, running as a centralized VNF,
> can control and manage multiple UP instances, which may be distributed
> and separated from the CP via a multi-hop L2 or L3 network.  CUPS
> requires protocols for communication between CP and UP instances: from
> the CP to the UP to create and manage subscriber state instances and
> from the UP to the CP to handle relevant solicited or unsolicited events.
>
> The proposed Working Group is a narrowly scoped WG tasked to specify
> communication protocol(s) between the CP and UP of a BNG, a network
> element whose functions are defined by BBF. A BNG can deliver broadband
> services to subscriber over wireline access or over multiple access
> types to accommodate different deployments. The goal of the WG is to
> define protocol(s) for CUPS that may support multiple deployment
> scenarios for the BNG.
>
> The scope of the work covers protocol requirements, specification of the
> communications protocol, the information elements to be transferred with
> that protocol, and YANG data model(s) for Operations and Management as
> well as security, operational, and transport considerations.
> ---
>
>
> Thank you
> Martin
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