Re: [aqm] I-D Action: draft-ietf-aqm-recommendation-04.txt

[Simon Barber <[e-mail]>]

Hi Roland,

My recent attention to DSCP has come from looking at what correct 
mappings to 802.1D (now 802.1Q) would be. I have also run across a 
couple of comments that legacy IP Precedence maps CS1 -> higher priority 
than BE. Do you have any knowledge of how prevalent this interpretation 
would be today, and whether it happens in any place that would be a 
problem? (i.e. are there applications that would generate these values, 
and rely on the behaivour, or routers that mis-prioritize things at 
places that are likely a bottleneck)? I.E. How important is it to 
consider these legacy behaivours today?

Simon

On 5/18/2015 8:52 AM, Bless, Roland (TM) wrote:
> CS1 is maybe a problem because originally (rfc 2474) CS1 means better 
> priority than CS0. At that point in time of RFC3662 the discussion was 
> to use CS1, because also in 802.1p 1 means "background". However, this 
> inconsistency makes it now hard to rely on any semantics of DSCP CS1. 
> IIRC the Diffserv chairs were opposed to spend another DSCP on LE and 
> therefore proposed to use an existing one. In retrospect, this seems 
> to have been a wrong decision given the problems of rtcweb and so on 
> these days.

> Regards, Roland