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Cisco MWR 2941 Mobile Wireless Edge Router Release 3.5 Command Reference, Cisco IOS Release 15.1(3)MR

OL-26895-01

Chapter Cisco MWR 2941 Router Command Reference, Release 15.1(3)MR

police (percent)

Bandwidth and Hierarchical Policy Maps

The police (percent) command uses the maximum rate of bandwidth available as the reference point for

calculating the bandwidth percentage. When the police (percent) command is configured in a child

policy map, the police (percent) command uses the bandwidth amount specified in the next higher-level

policy (in this case, the parent policy map). If the parent policy map does not specify the maximum

bandwidth rate available, the police (percent) command uses the maximum bandwidth rate available on

the next higher level (in this case, the physical interface, the highest point in the hierarchy) as the

reference point. The police (percent) command always looks to the next higher level for the bandwidth

reference point. The following sample configuration illustrates this point:

Policymap parent_policy

class parent

shape average 512000

service-policy child_policy

Policymap child_policy

class normal_type

police cir percent 30

In this sample configuration, there are two hierarchical policies: one called parent_policy and one called

child_policy. In the policy map called child_policy, the police command has been configured in the class

called normal_type. In this class, the percentage specified by for the police (percent) command is

30 percent. The command will use 512 kbps, the peak rate, as the bandwidth reference point for class

parent in the parent_policy. The police (percent) command will use 512 kbps as the basis for calculating

the cir rate (512 kbps * 30 percent).

interface serial 4/0

service-policy output parent_policy

Policymap parent_policy

class parent

bandwidth 512

service-policy child_policy

In the above example, there is one policy map called parent_policy. In this policy map, a peak rate has

not been specified. The bandwidth command has been used, but this command does not represent the

maximum rate of bandwidth available. Therefore, the police (percent) command will look to the next

higher level (in this case serial interface 4/0) to get the bandwidth reference point. Assuming the

bandwidth of serial interface 4/0 is 1.5 Mbps, the police (percent) command will use 1.5 Mbps as the

basis for calculating the cir rate (1500000 * 30 percent).

How Bandwidth Is Calculated

The police (percent) command is often used in conjunction with the bandwidth and priority commands.

The bandwidth and priority commands can be used to calculate the total amount of bandwidth available

on an entity (for example, a physical interface). When the bandwidth and priority commands calculate

the total amount of bandwidth available on an entity, the following guidelines are invoked:

• If the entity is a physical interface, the total bandwidth is the bandwidth on the physical interface.

• If the entity is a shaped ATM permanent virtual circuit (PVC), the total bandwidth is calculated as

follows:

–

For a variable bit rate (VBR) virtual circuit (VC), the sustained cell rate (SCR) is used in the

calculation.

–

For an available bit rate (ABR) VC, the minimum cell rate (MCR) is used in the calculation.

For more information on bandwidth allocation, refer to the “Congestion Management Overview” chapter

in the Cisco IOS Quality of Service Solutions Configuration Guide.

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