Re: [rtcweb] Comments on draft-jennings-rtcweb-qos (Re: Call for adoption of QoS draft)

[Harald Alvestrand <[e-mail]>]

On 09/17/2012 03:56 PM, Martin Thomson wrote:
> On 17 September 2012 15:19, Cullen Jennings (fluffy) <[e-mail]> wrote:
>> I have not tracked this all down but have been told that it might not be possible for a browser to do this in some versions of the windows operating system so I suspect the DSCP would end up being SHOULD not a MUST
> As I understand it, setting DSCP can be disabled by group policy.
> This is an explicit request from certain network operators, usually
> enterprises who have the ability to set such policies.
>
> As a matter of interest, some of the same networks do still perform
> traffic prioritization for audio and video traffic.  They do it based
> on port ranges.  You could infer some requirements from that.
<choosing to not go with the witty repartee>

The normal case for client-server communication is that the server has 
fixed port numbers, and the client just uses the port number the OS 
gives it; the network's priority setting is then done on the server port 
number range.

There are "fun" issues with trying to set port numbers on clients, 
including how to ACL them (I don't know of an OS that can do that), and 
the problem of port number collision.
For client-client communication, I think DSCP has a better chance of 
succeeding (not a big chance. Just a better chance).