Set a Rate Policy
Using a rate policy, you can establish a minimum rate for each
flow of an application, allow the flow prioritized access to excess bandwidth
if it's available, and set a limit on the total bandwidth that a flow
can consume. A rate policy is especially suited for traffic that tends
to burst.
A rate policy enables precise management of TCP traffic. For User Datagram
Protocol (UDP) traffic, a rate policy uses delay-bound scheduling. Rate
policies are not recommended for non-IP traffic.
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Note: To perform this task from PolicyCenter, you must first select a group and/or unit configuration from the Group:
and Unit: drop-down lists at the top of the page.
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To apply a rate policy to a traffic class:
1. Click the manage tab.
2. In the left window pane, select the class to which
you want to apply a rate policy.
3. Click policy and select add from
the drop-down list. The New Policy window appears.
4. Click rate in the New Policy window.
 show screen
5. Configure the policy's attributes, as described
in the following table:
| Field |
Description |
| Guaranteed |
The minimum guaranteed rate given to each connection. Rates may
be specified as integer bits per second, followed by a “k”
(thousands) or “M” (millions). When a specific minimum rate
is not required, set the rate to 0 bps and configure the Burstable
option.
Tip: You can use the traffic flow command in the CLI
to see how many concurrent flows of a specific type are present. This
will help to estimate guaranteed rate requirements.
Note: If the traffic class has a partition, be sure that the
guaranteed rate setting does not exceed the committed partition size.
To determine the committed partition size, look at the Size
field in the Partition window. If the policy's guaranteed rate
is higher than the committed partition size, each flow will be "squeezed"
to less than 256 bps, thereby invoking admission control. For information
on admission control, see Apply Admission
Control. |
| Burstable at Priority |
When this checkbox is selected, the traffic class can access unused
bandwidth at the specified priority level (0-7, where 7 is the highest
priority). The priority level defines how this class will compete
with other classes for excess bandwidth. Priority 7 is very assertive,
so save it for the most important traffic types. See Priority
Guidelines. |
Limit
(optional) |
Caps the excess rate available to the selected class. If a limit
is specified, it must be a minimum of 256 bps and must be greater
than the policy's guaranteed rate. |
Certain types of traffic offer specialized rate policy
options. The Policy window displays buttons for the following
functions if they are relevant to the selected traffic type:
6. Click add policy.
Note: In order for policies to take effect, traffic shaping must
be enabled. See Enable/Disable
Traffic Shaping.
See also:
Rate Policy Examples
How Bandwidth is Allocated
Protect
Critical Application Performance
Insulate
Users of the Same Application
Policy Overview
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