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New Member

what appened when use both bandwidth percent and police cir commands ?

Hi,

I attempt to understand configuration below:

TRAFFIC CLASSICIATION (I have only af31 and 1F11 in reality:

************************************************************************

class-map DSCP-OUT-D1INP

match not access-group DSCP-OUT-PROBE

match ip dscp  af31

exit

class-map DSCP-OUT-D2INP

match not access-group DSCP-OUT-PROBE

match ip dscp  af21

exit

class-map DSCP-OUT-D3INP

match not access-group DSCP-OUT-PROBE

match ip dscp  af11

exit

POLICIES APPLIED TO MY CLASSIFIED TRAFFIC:

***********************************************************

policy-map COS-OUT-D1

class DSCP-OUT-D1INP

  police cir 552 6900 => Normally police cir is indicated in bps but in my case it seems to be indicated in kbps ???

  police exceed-action set-dscp-transmit 28

exit

exit

policy-map COS-OUT-D2

class DSCP-OUT-D2INP

  police cir 276 4500

  police exceed-action set-dscp-transmit 20

exit

exit

policy-map COS-OUT-D3

class DSCP-OUT-D3INP

  police cir 92 4500

  police exceed-action set-dscp-transmit 12

exit

exit

GLOBAL POLICY APPLIED ON OUTPUT TRAFFIC:

************************************************************

policy-map COS-OUT

class DSCP-OUT-D1

  bandwidth percent 60 =>Does this parameter applie on normal traffic or during a congestion ? (For me, is during a congestion)

  service-policy COS-OUT-D1 => Why using police cir and bandwidth in a same time ?

exit

class DSCP-OUT-D2

  bandwidth percent 30

  service-policy COS-OUT-D2

exit

class DSCP-OUT-D3

  bandwidth percent 10

  service-policy COS-OUT-D3

exit

exit

interface atm 0.1

pvc ipoa vpi 8 vci 35

  ip address X.X.X.X Y.Y.Y.Z

  encapsulation mux

  inarp no

  qos vbr pcr 1280000 scr 1280000 mbs 1

  tx-ring max-buffers 4

  oam end-loopback

  execute

exit

description *** To my link description ***

service-policy input COUNT-IN

service-policy output COS-OUT

exit

**********************************************

police cir 552 6900 => Normally police cir is indicated in bps but in my case it seems to be indicated in kbps ???

bandwidth percent 60 =>Does this parameter applie on normal  traffic or during a congestion ? (For me, is during a congestion)

service-policy COS-OUT-D1 => Why using police cir and bandwidth in a same time ?

Which of both parameters (bandwidth percent and service-policy) will be applied in priority ?

I'am not an expert on Cisco QoS but I must be understanding this configuration for my client. Could you please help to understand correctly QoS configuration above ?

Thanks in advance, regards,

Franck

5 REPLIES
Super Bronze

Re: what appened when use both bandwidth percent and police cir

Disclaimer

The  Author of this posting offers the information contained within this  posting without consideration and with the reader's understanding that  there's no implied or expressed suitability or fitness for any purpose.  Information provided is for informational purposes only and should not  be construed as rendering professional advice of any kind. Usage of this  posting's information is solely at reader's own risk.

Liability Disclaimer

In  no event shall Author be liable for any damages whatsoever (including,  without limitation, damages for loss of use, data or profit) arising out  of the use or inability to use the posting's information even if Author  has been advised of the possibility of such damage.

Posting

CBWFQ's bandwidth command sets a logical minimum bandwidth guarantee (physically the command sets a descheduler weight).  The police (or shape) statement will set a hard bandwidth limit.

New Member

what appened when use both bandwidth percent and police cir comm

Thanks for your explanation,

After some search it seems that "bandwidth percent 60" permit to allocate a minimum of 60% of bandwdith during congestion. In addition, "police cir" and "police exceed-action" commands permit to threat more subtly the trafic during congestion for af31 trafic only.

In addition, I don't understand unit type used in commands below:

qos vbr pcr 1280000 scr 1280000 mbs 1 => this line correspond to a 1 megabit link but when I applying formula on cell rate result is illogical ????

police cir 552 6900 => normally cir/mir must be indicated in bps and this value must be between 8000 and 64000. Is it possible to use other values depending of routeur type ?

Thanks for your help, regards,

Franck

Super Bronze

Re: what appened when use both bandwidth percent and police cir

Disclaimer

The  Author of this posting offers the information contained within this  posting without consideration and with the reader's understanding that  there's no implied or expressed suitability or fitness for any purpose.  Information provided is for informational purposes only and should not  be construed as rendering professional advice of any kind. Usage of this  posting's information is solely at reader's own risk.

Liability Disclaimer

In  no event shall Author be liable for any damages whatsoever (including,  without limitation, damages for loss of use, data or profit) arising out  of the use or inability to use the posting's information even if Author  has been advised of the possibility of such damage.

Posting

The percentage in the bandwidth command, only is "accurate" if all 100% of the bandwidth had been defined, and all classes want at least the defined percentage of bandwidth.  Further, even though scheduler will dequeue traffic to try to meet the defined percentage, different traffic type behaviors can also skew actual bandwidth being used.

Yes, the police command is more exacting enforcing a bandwidth limitation.

The VBR command is something specific to ATM, and as ATM measures bandwidth consumption in cell transmission rates across virtual ATM circuits, it's very logical.  To understand it better you need to understand ATM.

All 3 can be used together to help form a QoS policy for certain conditions.  For example, the VBR command may define the maximum capacity an ATM PVC, while the and width command and police commands set minimum and maximum bandwidth limitation for a class of traffic using the PVC (assuming you have more than one class of traffic that will be using the ATM PVC).

New Member

Re: what appened when use both bandwidth percent and police cir

Thanks for your response.

I have not a comprehension problem of vbr, pcr,scr and mbs attribute but with the values of these parameters. 1280000 seems to be a highest value for 1 Megabit link.

It's the same question for values 552 and 6900 in "police cir 552 6900" command. If it's bps it's not enough and if it's kbps 6900 is too important. So, it difficult for me to understand correctly this provider configuration (it's not mine).

What do you think of these values ?

Super Bronze

Re: what appened when use both bandwidth percent and police cir

Disclaimer

The  Author of this posting offers the information contained within this  posting without consideration and with the reader's understanding that  there's no implied or expressed suitability or fitness for any purpose.  Information provided is for informational purposes only and should not  be construed as rendering professional advice of any kind. Usage of this  posting's information is solely at reader's own risk.

Liability Disclaimer

In  no event shall Author be liable for any damages whatsoever (including,  without limitation, damages for loss of use, data or profit) arising out  of the use or inability to use the posting's information even if Author  has been advised of the possibility of such damage.

Posting

Without knowing much more about the circuit and what the QoS goals are, can't really comment whether the settings make sense.

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