From: Snow, Tim (timothy.snow@eds.com)
Date: Wed Jan 21 2004 - 01:35:19 GMT-3
Dscp to switch priority map. It is used to signal a priority aware switch
fabric.
The default DSCP-to-switch-priority map maps DSCPs 0 to 15 to priority 0,
DSCPs 16 to 31 to
priority 1, DSCPs 32 to 47 to priority 2, and DSCPs 48 to 63 to priority 3.
Dscp-switch priority map:
d1 : d2 0 1 2 3 4 5 6 7 8 9
---------------------------------------
0 : 00 00 00 00 00 00 00 00 00 00
1 : 00 00 00 00 00 00 01 01 01 01
2 : 01 01 01 01 01 01 01 01 01 01
3 : 01 01 02 02 02 02 02 02 02 02
4 : 02 02 02 02 02 02 02 02 03 03
5 : 03 03 03 03 03 03 03 03 03 03
6 : 03 03 03 03
I wish I had a better explanation for you, but I don't.
T
#12042
-----Original Message-----
From: ccie2be [mailto:ccie2be@nyc.rr.com]
Sent: Tuesday, January 20, 2004 10:59 PM
To: Snow, Tim
Cc: ccielab@groupstudy.com
Subject: Re: 3550 QoS
Thanks Tim for getting back to me.
I have to admit though, I don't understand your answer. What does cos have
to do with "switch priority" and what does "switch priority" have to do with
the cos to dscp map? I'm sorry if I'm a bit thick skulled but I'm still
hoping you can explain this to me in a way I can understand.
If you see from the map table below, "switch priority" has 4 possible
values: 0, 1, 2, and 3. What do these values mean? And, under what
circumstances should I want or need to change them? And, if I'm going to
change them, what should I change them to?
Thanks in advance
----- Original Message -----
From: "Snow, Tim" <timothy.snow@eds.com>
To: "'ccie2be'" <ccie2be@nyc.rr.com>
Cc: <ccielab@groupstudy.com>
Sent: Tuesday, January 20, 2004 10:38 PM
Subject: RE: 3550 QoS
> The values are used internally when the switch maps cos to dscp for
queueing
> purposes.
>
> T
> #12042
>
> -----Original Message-----
> From: ccie2be [mailto:ccie2be@nyc.rr.com]
> Sent: Tuesday, January 20, 2004 7:13 PM
> To: Group Study
> Subject: 3550 QoS
>
>
> Hi,
>
> If you do a "show mls qos map", one of the tables you'll find
> according
to
> the 3550 command reference is the DSCP-to-Switch Priority and it looks
like
> this:
>
> Dscp-switch priority map:
> d1 : d2 0 1 2 3 4 5 6 7 8 9
> ---------------------------------------
> 0 : 00 00 00 00 00 00 00 00 00 00
> 1 : 00 00 00 00 00 00 01 01 01 01
> 2 : 01 01 01 01 01 01 01 01 01 01
> 3 : 01 01 02 02 02 02 02 02 02 02
> 4 : 02 02 02 02 02 02 02 02 03 03
> 5 : 03 03 03 03 03 03 03 03 03 03
> 6 : 03 03 03 03
>
> See the following link:
>
>
http://www.cisco.com/univercd/cc/td/doc/product/lan/c3550/12119ea1/3550cr/cl
> i
> 2.htm#2418454
>
> It seems to me that this Switch Priority has nothing to do with
> Spanning Tree (true?). I tried finding out what they mean by "Switch
> Priority",
but
> didn't come up with anything. Can anybody tell me what "Switch
> Priority"
is
> and where I can find additional info on it?
>
> Thanks in advance, dt
>
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