[tsvwg] NQB: WiFi e23 traversal - text proposal

["Black, David" <[e-mail]>]

>> [SM] Now, NQB also offers a higher chance of e2e traversal (or NQB will have failed), here is the 64K question, from the perspective of a potential abuser, does this outway the small risk of degradation?



> That's ultimately an engineering judgement call that I think ought to be noted in the draft.  I would expect that the higher likelihood of traversal is

> accompanied by a higher likelihood of full NQB support in the traversed networks, bringing traffic protection and shallow queues into play.

> I'll post some proposed text changes to the list in the next day or so.

Working from the 3 paragraphs that Greg posted, I have a proposed additional sentence to add to the end of the first paragraph:

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As stated above, the use of DSCP 45 (decimal) for NQB is not expected to create incentives for abuse by non-compliant applications in the Wi-Fi uplink direction.  The fact that the NQB DSCP brings with it the potential for degradation of non-compliant applications (traffic protection and/or a shallow queue resulting in reordering and/or packet loss) plus the existence of multiple other DSCP values that don't carry the risk of degradation, and which could be readily used to obtain prioritization (AC_VI or even AC_VO), leads to the conclusion that NQB non-compliant applications that are seeking prioritization in the Wi-Fi uplink would be better off selecting one of those other DSCPs.
NEW
This conclusion is not disturbed by network support for NQB increasing the likelihood of DSCP 45 traffic traversing network boundaries without change to the DSCP, as that likelihood of increased network boundary traversal is balanced by a likelihood of NQB traffic encountering the traffic-limiting aspects of NQB support, traffic protection and shallow buffers, which limit the potential for abuse.
END
In the case of traffic originating outside of the Wi-Fi network, the prioritization of traffic marked with the NQB DSCP via the Video Access Category (if left unchanged) could potentially erode the principle of alignment of incentives discussed in [Section 5]. In order to preserve the incentives principle for NQB, Wi-Fi systems MAY be configured such that the EDCA parameters for the Video Access Category match those of the Best Effort Access Category, which will mean AC_VI is at the same priority level as AC_BE. These changes might not be possible on all Access Points, and in any case the requirements and recommendations in [Section 4.4.1] would apply in this situation.

Similarly, systems that utilize [RFC8325 [ietf.org]<https://urldefense.com/v3/__https:/www.ietf.org/archive/id/draft-ietf-tsvwg-nqb-25.html*RFC8325__;Iw!!LpKI!kEwuENwtM7AUFzztaj3PiFHXT65NvS4zhUuZQAzzfTnGpTlcXesLcE9v4Ias5OmEsjF0nCbo_L--A9LJEgs$>;] but cannot provide a separate AC_BE queue for NQB traffic, SHOULD map the recommended NQB DSCP 45 (decimal) (or the locally determined alternative) to UP_5 in the "Video" Access Category (see [Section 7.3.2]).
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Thanks, --David

David L. Black, Sr. Distinguished Engineer, Technology & Standards
Infrastructure Solutions Group, Dell Technologies
mobile [phone] [e-mail]<mailto:[e-mail]>