Re: "POliced-dscp transmit"

From: Narbik Kocharians (narbikk@gmail.com)
Date: Sun Feb 22 2009 - 16:10:48 ARST

The "policed-dscp" option can be used when you need to set the DSCP for the
conforming traffic to one value and the out of profile traffic to another
value. For example if you look at Daniels example, where he has mapped 40 to
8, this is what you would do:

I am NOT in front of a rack and i am doing this from memory so i apologies
if there are any typos. Let's assume that the "*class-map QOS*" is already
configured.

Policy-map TST
  class QOS
    set dscp 40
    police 1000000 8000 exceed-action policed-dscp-transmit

 Remember that we are configuring a switch and the conform-action is NOT
available, therefore, In this case you are marking the conforming traffic to
a DSCP value of 40 and you are also saying that the out of profile traffic
should be referring to the "policed-dscp" map.

Since the mapping by default is one-to-one, you must change that mapping to
reflect your configuration:

*mls qos map policed-dscp 40 to 8*

If you do a "*Show mls qos map policed-dscp*" you will see that the "d1 and
the d2" specify the conforming traffic and the body of the message refers to
the out of profile traffic.

For example, to see dscp 40, d1: (vertically) displays the "4" in the 40 and
the d2: (horizontally) displays the "0" in 40.
If you check where these two lines meet, you should see 8, which is the DSCP
vlaue set for the out of profile traffic.

On Sun, Feb 22, 2009 at 8:05 AM, NET HE <he_net@hotmail.com> wrote:

> This is what I understand. Since I couldn't lab it up, maybe somebody can
> correct me.
>
>
>
> When MLS QOS is enable on a switch, for ingress packets the switch must
> refer
> to a internal DSCP for qos processing, and then the egress packets DSCP
> field
> is replaced by the internal DSCP value. The flows would be, for example,
>
>
>
> Case 1: trust COS, regardless it's configured by policy-map or interface
> command. The switch then uses cos-to-dscp map to create the internal DSCP
> value.
>
>
>
> Case 2: trust DSCP, regardless it's configured by policy-map or interface
> command. The switch then uses dscp-to-dscp-mutation map to create the
> internal
> DSCP value.
>
>
>
> Case 3: trust IP Precedence, regardless it's configured by policy-map or
> interface command. The switch then uses ip-precedence-to-dscp map to create
> the internal DSCP value.
>
>
>
> *Case 4: policy-map police exceed-action policed-dscp-transmit, the switch
> then uses police-dscp-map to create the internal DSCP value for exceeding
> traffic.
>
>
>
> Best Regards,
> Net (Xin) He
>
>
>
>
> > Date: Sun, 22 Feb 2009 16:11:57 +0530
> > Subject: "POliced-dscp transmit"
> > From: gauravmadan1177@gmail.com
> > To: ccielab@groupstudy.com
> >
> > Hi Group
> >
> > I am not at all able to understand what this command achieves under
> > policy-map clas config
> >
> > exceed-action policed-dscp-transmit
> > Which global mapp it reads and how ..
> >
> > Rack1SW4#show mls qos maps ?
> > cos-dscp cos-dscp map keyword
> > cos-input-q cos-input queue map keyword
> > cos-output-q cos-output queue map keyword
> > dscp-cos dscp-cos map keyword
> > dscp-input-q dscp-input queue map keyword
> > dscp-mutation dscp-mutation map keyword
> > dscp-output-q dscp-output queue map keyword
> > ip-prec-dscp ip-prec-dscp map keyword
> > policed-dscp policed-dscp map keyword <<<<<<<<<<<<<<<<
> > | Output modifiers
> > <cr>
> > Rack1SW4#show mls qos maps po
> > Rack1SW4#show mls qos maps policed-dscp
> > Policed-dscp map:
> > d1 : d2 0 1 2 3 4 5 6 7 8 9
> > ---------------------------------------
> > 0 : 00 01 02 03 04 05 06 07 08 09
> > 1 : 10 11 12 13 14 15 16 17 18 19
> > 2 : 20 21 22 23 24 25 26 27 28 29
> > 3 : 30 31 32 33 34 35 36 37 38 39
> > 4 : 40 41 42 43 44 45 46 47 48 49
> > 5 : 50 51 52 53 54 55 56 57 58 59
> > 6 : 60 61 62 63
> >
> >
> > I will be greatful ; if someone explain this or give pouinter to good
> write
> > up on this .
> >
> > Gaurav Madan
> >
> >
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-- 
Narbik Kocharians
CCSI#30832, CCIE# 12410 (R&S, SP, Security)
www.MicronicsTraining.com
www.Net-Workbooks.com
Sr. Technical Instructor

Blogs and organic groups at http://www.ccie.net

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