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Cisco ASR 901 Aggregation Services Router Command Reference Guide
OL-26031-07
Chapter 1 CLI Command Reference
shape (percent)
The calculated CIR bps rate must be in the range of 8000 and 154,400,000 bps. If the rate is less than
8000 bps, the associated policy map cannot be attached to the interface. If the interface bandwidth
changes (for example, more is added), the CIR bps values are recalculated on the basis of the revised
amount of bandwidth. If the CIR percentage is changed after the policy map is attached to the interface,
the bps value of the CIR is recalculated.
Conform Burst and Peak Burst Sizes in Milliseconds
This command also allows you to specify the values for the conform burst size and the peak burst size
in milliseconds. If you want bandwidth to be calculated as a percentage, the conform burst size and the
peak burst size must be specified in milliseconds (ms).
The traffic shape converge rate depends on the traffic pattern and the time slice (Tc) parameter, which is
directly affected by the bc that you configured. The Tc and the average rate configured are used to
calculate bits per interval sustained. Therefore, to ensure that the shape rate is enforced, use a bc that
results in a Tc greater than 10 ms.
How Bandwidth Is Calculated
The
shape
(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, see the “Congestion Management Overview” chapter in
the
Cisco IOS Quality of Service Solutions Configuration Guide.
Examples
The following example configures traffic shaping using an average shaping rate on the basis of a
percentage of bandwidth. In this example, 25 percent of the bandwidth has been specified. Additionally,
an optional be value and bc value (100 ms and 400 ms, respectively) have been specified.
Router>
enable
Router#
configure terminal
Router(config)#
policy-map policy1
Router(config-pmap)#
class-map class1
Router(config-pmap-c)#
shape average percent 25 20 ms be 100 ms bc 400 ms
Router(config-pmap-c)#
end
After the policy map and class maps are configured, the policy map is attached to interface as shown in
the following example.
Router>
enable
Router#
configure terminal
Router(config)#
interface gigabitethernet0/1
Router(config-if)#
service-policy input policy1
Router(config-if)#
end
Related Commands
