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Beginner

## Dual Rate Policing vs Shape Peak

Hi everyone!!!

Someone knows which is the difference between Dual Rate Policing (police cir pir) and Shaping with Shape Peak?

Do they fill the token bucket every Tc?

Thanks a lot!!!!

Juan

Everyone's tags (6)
1 ACCEPTED SOLUTION

Accepted Solutions

## Re: Dual Rate Policing vs Shape Peak

Hello

Shaping comes into play on your routers when your physical wan lines exceeds the your traffic rate by the ISP  or your neighboring site- eg: your access rate is 2mb but your  CIR ( committed information rate) is 1MB.

You can shape an average/peak/percent/rate/percent/percent remaining)  And all are different

However Shape average and Shape peak allow bursting of traffic

Note:
Shaping  is always an egress function- (exiting router) - queuing so router can use queuing tools to give better performance of particular type of packet

(Committed burst =BC & Excessive bursts=BE with a defined Time Interval = TC

Shape value = bps
Bc/Be value =bytes per second

Shaping average & peak tc/bc/values

Bc=Tc*CIR/8

Tc=Bc/Shaped rate(CIR

Be=Bc

TC= 0.125 default

TC= 0.025 for lower 320kps

TC= 0.010 for sensitive applications

BC=Tc*CIR
.125*640000=8000

Shape average ( default BC no BE)

Shape average 10240000

Shape average 10240000(bits) bc of 16000(bytes)
( this would send 16K bytes every .125  of a secs = 128000 byes *8 =1024000

Shape peak works a bit differently as it allows both Bc& Be to be sent over the TC
Shape peak
Shape peak 5120000 (mean to actual shape at 10240000)
Shape peak 5120000 (bits) bc of 8000(bytes)  Be 8000(bytes)

( 5120000 (1+8000/8000 = 10240000)

Policing default - entering first device in network from being overrun with too much traffic
===============================================================

Single rate, single bucket/two colour ( no violate acction or Be configured/no PIR)
BC = CIR/32
or
BC =CIR*0.25/8

Be=0

Single rate, Dual bucket/three colour (violate acction and/or Be configured/ no PIR)
BC = CIR/32
or
BC =CIR*0.25/8

Be=BC

Dual rate, Dual bucket/three colour (PIR is configured)
BC = CIR/32
or
BC =CIR*0.25/8

BE - PIR/32
or
BE =CIR*0.25/8

res

Paul

Thanks.

kind regards
Paul

Please rate and mark posts accordingly if you have found any of the information provided useful.
It will hopefully assist others with similar issues in the future
6 REPLIES 6
Hall of Fame Cisco Employee

## Dual Rate Policing vs Shape Peak

Hello Juan,

The Dual Rate Policing allows you to achieve two sustained rates - the CIR and EIR, in each timing interval. In effect, the Dual Rate Policing allows you to continuously send data at the total rate of CIR+EIR. This is accomplished by refilling both the Bc and Be buckets every Tc interval independently and simultaneously.

Regarding the shape peak - this is a matter of quite extensive debates. I suggest reading the following threads:

https://supportforums.cisco.com/message/3297548#3297548

https://supportforums.cisco.com/message/3510675#3510675

Best regards,

Peter

Beginner

## Dual Rate Policing vs Shape Peak

Thanks Peter!!!

Do you know why do the people recomend utilize this formula to shaping?

Bc= policerate x 1,5 /8

## Re: Dual Rate Policing vs Shape Peak

Hello

Shaping comes into play on your routers when your physical wan lines exceeds the your traffic rate by the ISP  or your neighboring site- eg: your access rate is 2mb but your  CIR ( committed information rate) is 1MB.

You can shape an average/peak/percent/rate/percent/percent remaining)  And all are different

However Shape average and Shape peak allow bursting of traffic

Note:
Shaping  is always an egress function- (exiting router) - queuing so router can use queuing tools to give better performance of particular type of packet

(Committed burst =BC & Excessive bursts=BE with a defined Time Interval = TC

Shape value = bps
Bc/Be value =bytes per second

Shaping average & peak tc/bc/values

Bc=Tc*CIR/8

Tc=Bc/Shaped rate(CIR

Be=Bc

TC= 0.125 default

TC= 0.025 for lower 320kps

TC= 0.010 for sensitive applications

BC=Tc*CIR
.125*640000=8000

Shape average ( default BC no BE)

Shape average 10240000

Shape average 10240000(bits) bc of 16000(bytes)
( this would send 16K bytes every .125  of a secs = 128000 byes *8 =1024000

Shape peak works a bit differently as it allows both Bc& Be to be sent over the TC
Shape peak
Shape peak 5120000 (mean to actual shape at 10240000)
Shape peak 5120000 (bits) bc of 8000(bytes)  Be 8000(bytes)

( 5120000 (1+8000/8000 = 10240000)

Policing default - entering first device in network from being overrun with too much traffic
===============================================================

Single rate, single bucket/two colour ( no violate acction or Be configured/no PIR)
BC = CIR/32
or
BC =CIR*0.25/8

Be=0

Single rate, Dual bucket/three colour (violate acction and/or Be configured/ no PIR)
BC = CIR/32
or
BC =CIR*0.25/8

Be=BC

Dual rate, Dual bucket/three colour (PIR is configured)
BC = CIR/32
or
BC =CIR*0.25/8

BE - PIR/32
or
BE =CIR*0.25/8

res

Paul

Thanks.

kind regards
Paul

Please rate and mark posts accordingly if you have found any of the information provided useful.
It will hopefully assist others with similar issues in the future
Highlighted
Beginner

## Re: Dual Rate Policing vs Shape Peak

Guauuu pdriver and all guys, many thanks!!! i´m very grateful. Many thanks from Argentina.

I have some ask for pdriver.

1. Why you say that the Bc and Be are configured in bytes? Like Cisco and his command reference, there are values in bits.

2. Like some docs by Cisco, the shape average has Be by default, and the value is the same that Bc. Is this correct?

3.What does command allows me to have more bandwidth? shape average 512000 or shape peak 256000?

I think, that after a period of inactivity, the shape average allow me 512000, plus the Be.

Thanks a lot!!!!

Juan from Argentina.

VIP Expert

## Re: Dual Rate Policing vs Shape Peak

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Posting

It's a rule-of-thumb to allow for bursting.

Hall of Fame Cisco Employee

## Re: Dual Rate Policing vs Shape Peak

Hello Juan,

To be honest, I am not familiar with that formula. In any case, in these matters, I completely trust Joseph Doherty who answered that is a rule of thumb.

Best regards,

Peter