From: SANCHEZ-MONGE,ANTONIO (HP-France,ex2) (antonio.sanchez-monge@hp.com)
Date: Wed Jan 21 2004 - 14:23:56 GMT-3
Hi,
I talked about IP precedence, not about CoS ;)
Cheers,
Ato.
-----Original Message-----
From: ccie2be [mailto:ccie2be@nyc.rr.com]
Sent: miircoles, 21 de enero de 2004 15:24
To: SANCHEZ-MONGE,ANTONIO (HP-France,ex2)
Cc: ccielab@groupstudy.com
Subject: Re: 3550 QoS
Hey Antonio,
Thanks for getting back to me.
IMHO, I think you're mistaken on this one because there's a different
command used for mapping cos to queue. That command is " wrr-queue cos-map
<q#> <cos#, cos#...>
I suppose it's possible for there to be 2 commands which do the same thing,
but it doesn't sound right to me. Hopefully, somebody will clear this up.
dt
----- Original Message -----
From: "SANCHEZ-MONGE,ANTONIO (HP-France,ex2)" <antonio.sanchez-monge@hp.com>
To: "'ccie2be'" <ccie2be@nyc.rr.com>
Cc: <ccielab@groupstudy.com>
Sent: Wednesday, January 21, 2004 3:30 AM
Subject: RE: 3550 QoS
Morning guys,
IMHO this map corresponds to Weighted Round Robin (WRR) which assigns
packets to 4 egress queues depending on IP precedence. In fact
"DSCP-to-switch priority" name is confusing, since the 3 last bits of DSCP
are ignored, only IP precedence is taken into account. Basically,
precedences are distributed in groups of 2 (0-1, 2-3, 4-5, 6-7), and the
corresponding packets are assigned to weighted queues (round-robin algorithm
giving preference to highest precedence queues). More details in:
http://www.cisco.com/en/US/tech/tk389/tk813/technologies_tech_note09186a0080
1558cb.shtml#topic4
I hope this helps,
Ato.
-----Original Message-----
From: ccie2be [mailto:ccie2be@nyc.rr.com]
Sent: miircoles, 21 de enero de 2004 5:48
To: Snow, Tim
Cc: ccielab@groupstudy.com
Subject: Re: 3550 QoS
No problem. Maybe there's someone on Group Study who understands this
better and is willing to jump in. I posted that question because I read the
same thing in the command reference but didn't know what to make of it. I
recall something that sounded similar when I was learning about the Cat 5k
series but I don't even recall ever seeing anything that says whether or
not the 3550 is a priority aware switch or has a switch fabric.
dt
----- Original Message -----
From: "Snow, Tim" <timothy.snow@eds.com>
To: "'ccie2be'" <ccie2be@nyc.rr.com>
Cc: <ccielab@groupstudy.com>
Sent: Tuesday, January 20, 2004 11:35 PM
Subject: RE: 3550 QoS
> 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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