Re: [tsvwg] New Version Notification for draft-white-tsvwg-nqb-02.txt

["Smith, Kevin, (R&D) Vodafone Group" <[e-mail]>]

Thanks Greg and Thomas, this indeed looks beneficial for cellular networks, and I would be happy to discuss radio lab testing. It will be interesting to compare against best effort on 5G NR which has a reduced Time Transmission Interval (~7 times more frequent transmissions).

Two comments:
(1) Historically the addition of bearers was prohibitive due to expense, but that is now easier with the rise in Multi-RAB (Radio Access Bearer) devices. Note however that the definition of bearers and QOS changes in 5G, so a suggested addition is to append that to this sentence in 8.2:

> To support the NQB PHB, the mobile network MUST be configured to give UEs a dedicated, low-latency, non-GBR, EPS bearer with QCI 7 in
   addition to the default EPS bearer; >> or a Data Radio Bearer with 5QI 7 in a 5G system.

(Reference: Table 5.7.4-1: Standardized 5QI to QoS characteristics mapping in 3GPP TS 23.501, 'System Architecture for 5G'.
Acronym: QI = QoS Identifier )

(2) I think the key point for 8.2 is the volatility of cellular radio links due to rapidly changing SINR (Signal-to-Interference-plus-Noise Ratio) incurred by  devices. This causes sudden and drastic bandwidth fluctuations, as described in https://tools.ietf.org/html/draft-johansson-cc-for-4g-5g-02 , and especially under handover scenarios. As a result, and as a means to utilise as many radio resource blocks as possible when they become available, cellular operators often run deep buffers at the scheduler. This is not ideal for NQB traffic, hence the need to investigate your proposal.

The point about why operators typically run default bearers for Internet traffic is more complex than written here - other factors include historic cost and support of additional bearers, requirements to publish dropped voice call percentages, Net Neutrality in EU etc. , so I'm not sure it's worth going into detail; rather just to note the use of a single default "best effort" bearer.

All best,
Kevin


C2 General

-----Original Message-----
From: tsvwg <[e-mail]> On Behalf Of Greg White
Sent: 28 June 2019 21:21
To: [e-mail]
Subject: [tsvwg] FW: New Version Notification for draft-white-tsvwg-nqb-02.txt

All,

Thomas Fossati and I have posted an updated draft of the proposed NQB DSCP/PHB.  This version incorporates the relevant text from draft-fossati-tsvwg-lola, and discusses intersection with RFC8325 (DSCP-WMM mapping), thereby extending the use-case discussion beyond DOCSIS to include both mobile networks and WiFi.  I believe that we took into account all of the comments received on the previous draft (thanks all who provided comments), but please let us know if we missed something or if you believe we could/should have addressed them differently.

The technology proposed is independent of (but compatible with) the L4S architecture.

My hope is that TSVWG can consider this draft for adoption as a WG draft.

Best Regards,
Greg


On 6/28/19, 12:31 PM, "[e-mail]" <[e-mail]> wrote:


    A new version of I-D, draft-white-tsvwg-nqb-02.txt
    has been successfully submitted by Greg White and posted to the
    IETF repository.

    Name:draft-white-tsvwg-nqb
    Revision:02
    Title:Identifying and Handling Non Queue Building Flows in a Bottleneck Link
    Document date:2019-06-28
    Group:Individual Submission
    Pages:12
    URL:            https://www.ietf.org/internet-drafts/draft-white-tsvwg-nqb-02.txt
    Status:         https://datatracker.ietf.org/doc/draft-white-tsvwg-nqb/
    Htmlized:       https://tools.ietf.org/html/draft-white-tsvwg-nqb-02
    Htmlized:       https://datatracker.ietf.org/doc/html/draft-white-tsvwg-nqb
    Diff:           https://www.ietf.org/rfcdiff?url2=draft-white-tsvwg-nqb-02

    Abstract:
       This draft proposes the definition of a standardized DiffServ code
       point (DSCP) to identify Non-Queue-Building flows (for example:
       interactive voice and video, gaming, machine to machine
       applications), along with a Per-Hop-Behavior (PHB) that provides a
       separate queue for such flows.

       The purpose of such a marking scheme is to enable networks to provide
       and utilize queues that are optimized to provide low latency and low
       loss for such Non-Queue-Building flows (e.g. shallow buffers,
       optimized media access parameters, etc.).

       This marking scheme and PHB has been developed primarily for use by
       access network segments, where queuing delays and queuing loss caused
       by Queue-Building protocols are manifested.  In particular,
       applications to cable broadband links and mobile network radio and
       core segments are discussed.




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