Re: [tcpm] [tsvwg] inband signaling (was: Re: Agenda requests for TSVWG@IETF101)

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

HI Ingemar,

> The 3GPP QoS framework can be used to offer for instance a Guaranteed bandwidth (GBR) to applications. The operation is that the "bearer" gets increased scheduling priority once the throughput is below the GBR value.

That is technically correct: but a consideration to note here is that in LTE, operators typically operate only two bearers - one for IMS/VoLTE, which is GBR; and one 'best effort' (non-GBR) bearer for Internet traffic.  This is likely due to non-technical reasons.

Hence I also favour a bearer*-agnostic approach such as L4S, but appreciate that L4S will also have to operate within the constraints of the radio scheduler (which will still be 'best effort')

For 5G, certainly there can be more flexible and holistic scheduling approaches. For practical implementation though, all 'prioritisations' will need to meet regulatory directives on traffic management.

* i.e. GBR vs non-GBR bearer

All best,
Kevin


Vodafone Proprietary classified as C2 - Internal

-----Original Message-----
From: tsvwg [mailto:[e-mail]] On Behalf Of Ingemar Johansson S
Sent: 14 March 2018 07:56
To: [e-mail]; [e-mail]
Cc: Ingemar Johansson S <[e-mail]>; [e-mail]; [e-mail]; '[e-mail]' <[e-mail]>
Subject: Re: [tsvwg] [tcpm] inband signaling (was: Re: Agenda requests for TSVWG@IETF101)

Hi

This subject pops up every once in a while.

I would like to add my perspective, given how I understand that 3GPP technology works. The 3GPP QoS framework can be used to offer for instance a Guaranteed bandwidth (GBR) to applications. The operation is that the "bearer" gets increased scheduling priority once the throughput is below the GBR value.
In simulations I have verified that this framework can deliver a GBR to TCP flows when the network load increases, at least as long it is possible to push back other bearers with a lower priority. So, seen from my experience so far I am not fully confident that additional inband signaling is needed.

There can however be a benefit to e.g. determine an appropriate bitrate for a DASH session, depending on network load and/or coverage, but I would argue that out of band signaling is better in this case.

As regards to "worst case latency", I am not sure that I follow here, are we discussing TSN/Detnet technology here, general link failures, or is it about means to control the queue delay in the network ?. As to the latter, I believe that it is worthwhile to look more closely at L4S.

Regards
Ingemar Johansson


> Message: 2
> Date: Tue, 13 Mar 2018 19:27:18 +0000
> From: Lin Han <[e-mail]>
> To: Toerless Eckert <[e-mail]>, Gorry Fairhurst
> <[e-mail]>
> Cc: Thomas Nadeau <[e-mail]>, "[e-mail]"
> <[e-mail]>,  "[e-mail]" <[e-mail]>, "Scharf, Michael
> (Nokia - DE/Stuttgart)" <[e-mail]>,
> "[e-mail]" <[e-mail]>, Katsushi Kobayashi
> <[e-mail]>, Yingzhen Qu <[e-mail]>
> Subject: Re: [tcpm] [tsvwg] inband signaling (was: Re: Agenda requests
> for TSVWG@IETF101)
> Message-ID:
> <1D30AF33624CDD4A99E8C395069A2A162CDB9BA3@sjceml521-
> mbs.china.huawei.com>
>
> Content-Type: text/plain; charset="us-ascii"
>
> Hi, Gorry/Toerless
>
> Here is some explanation and clarification for two drafts
> (draft-han-tsvwg-cc and
> draft-han-6man-in-band-signaling-for-transport-qos)
>
> 1. About draft-han-tsvwg-cc compared with other CC for bandwidth
> guaranteed network, such as gTFRC.
> draft-han-tsvwg-cc is a split draft from
> draft-han-6man-in-band-signaling-for-
> transport-qos . It proposes a new CC for a network if the TCP
> session's bandwidth is guaranteed. Here the guaranteed  bandwidth is
> per TCP session and described by PIR/CIR and given directly by TCP end user.
>
> 2. About TCP-QS and draft-han-6man-in-band-signaling-for-transport-qos
> >From my understanding, TCP-QS and
> >draft-han-6man-in-band-signaling-for-
> transport-qos do have similarity, both are kind of using in-band
> signaling for the resource reservation. But they still have big difference.
> 1). draft-han-6man-in-band-signaling-for-transport-qos is more general
> in- band signaling method, it not only applies to TCP, but also UDP or
> other upper layer of protocol, even the draft only exemplifies the method to TCP.
> 2). draft-han-6man-in-band-signaling-for-transport-qos provides
> reserved resource for bandwidth and latency for the whole life of TCP
> session. It gives more flavors and more granularity for the QoS
> (unlike TCP-QS only has 16 values of starting bandwidth). Moreover, it
> can support the "worst case latency" at each hop; also, it can support
> the OAM to detect the congestion states, and support the "forwarding
> state" for host to be notified in real-time about if the resource
> reservation or QoS forwarding is interrupted by abnormal situation such as link/node failures.
>
> Best regards
>
> Lin
>