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

Simon Barber <simon@superduper.net> Sun, 24 May 2015 18:41 UTC

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Date: Sun, 24 May 2015 11:41:22 -0700
From: Simon Barber <simon@superduper.net>
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To: Mikael Abrahamsson <swmike@swm.pp.se>
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Subject: Re: [aqm] I-D Action: draft-ietf-aqm-recommendation-04.txt
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OK - so this is within ISP networks. Could this be avoided by mapping 
the DSCPs on entry and exit of their network? Do you know about CS1 
within ISP networks? Or any impact at the edge?

Simon


On 5/24/2015 11:33 AM, Mikael Abrahamsson wrote:
> On Sun, 24 May 2015, Simon Barber wrote:
>
>> 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?
>
> If ISPs today allowed DSCP marking to get propagated Internet wide and 
> didn't change their settings from what they have today, some would 
> treat AF1 and AF2 higher than BE, some would treat AF1 lower than BE 
> and AF2 higher than BE, some would treat AF1 and AF2 lower than BE.
>
> That's why I'm saying AF1 and AF2 for less-than-BE isn't incrementally 
> deployable.
>