Re: Doubt in QoS

From: Anderson Mota Alves (mota_anderson@hotmail.com)
Date: Thu Jun 29 2006 - 09:45:43 ART

Hi Petr,

Based on your explanation below it's more clear to me that you cannot mix
"priority" and "shape" because one is for policing and the other for
shaping purposes.

But I've been seaching in cisco webpage and from the link below it says:

You can specify two types of traffic shaping; average rate shaping and
peak rate shaping. Average rate shaping limits the transmission rate to
the CIR. Using the CIR ensures that the average amount of traffic being
sent conforms to the rate expected by the network.

Peak rate shaping configures the router to send more traffic than the
CIR. To determine the peak rate, the router uses the following formula:

peak rate = CIR(1 + Be / Bc)

http://www.cisco.com/en/US/products/sw/iosswrel/ps1835/products_command_reference_chapter09186a0080087f34.html#wp1077189

But how do I know that configuring the "shape average 96000" I can send
traffic up to 192 kbps?

Thanks,

Andy

  --------------------------------------------------------------------

  From: "Petr Lapukhov" <petr@internetworkexpert.com>
  To: "Anderson Mota Alves" <mota_anderson@hotmail.com>,
  <ccielab@groupstudy.com>
  Subject: Re: Doubt in QoS
  Date: Thu, 29 Jun 2006 14:42:55 +0400
>The first one seems to be "almost" correct:
>
>You shape (limit) traffic up to 96kbit here - the only problem
>is "peak" keyword. This configuration actually permits you to send
>traffic up to 192kbit by default. So I would better do something
>like:
>
>...
>class CRITICAL
> shape average 96000
> bandwidth 84
>...
>
>This way you guarantee 84k in case of congestion,
>and limit flow up to 96k in any case.
>
>As for your second example - you can not mix priority and bandwidth:
>
>R6(config-pmap-c)#priority 64
>R6(config-pmap-c)#bandwidth 92
>Must remove priority configuration from this class first.
>
>Also remember that you cannot mix "priority" and "shape",
>and dont forget that "priority" actually police your traffic in
>case of congestion.
>
>Finally, you may choose "police" instead of "shape", with
>your first example. The decision should depend on task wording.
>
>HTH
>---
>Petr Lapukhov, CCIE #16379
>petr@internetworkexpert.com
>
>Internetwork Expert, Inc.
>http://www.InternetworkExpert.com
>Toll Free: 877-224-8987
>Outside US: 775-826-4344
>
>----- Original Message ----- From: "Anderson Mota Alves"
><mota_anderson@hotmail.com>
>To: <ccielab@groupstudy.com>
>Sent: Thursday, June 29, 2006 2:16 PM
>Subject: Doubt in QoS
>
>
>>Hi gurus, The question I need to complish is the following:
>>
>>Which configuration provides the mission-critical traffic class
>>with a
>>minimum
>>
>>bandwidth guarantee of 84 kbps and a maximum upper bandwidth limit
>>of 96
>>
>>kbps?
>>
>>I think I have to solution for this one but I'm not sure if I'm
>>right:
>>
>>policy-map shape
>>class mission-critical
>>bandwidth 84
>>shape peak 96000
>>
>>or
>>
>>policy-map shape
>>class mission-critical
>>priority 64
>>bandwidth 96
>>
>>Could anyone tell me which one I could use? Also I don't know if in
>>order
>>to use the shape peak I need to first configure the shape cir ir
>>order to
>>make sure that this will be the peak above the Cir.
>>
>>Thanks
>>
>>_______________________________________________________________________
>>Subscription information may be found at:
>>http://www.groupstudy.com/list/CCIELab.html

This archive was generated by hypermail 2.1.4 : Sat Jul 01 2006 - 07:57:34 ART