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    Create Policies for Classes

    Select Modify > QoS > CoS Policies to define CoS policies.

    Figure 1: CoS Policies Window

    CoS Policies Window

    Field

    Description

    Router ID

    This specifies one of the existing routers that this CoS Policy is applied to. The "-" means that the policy will be applied to all routers.

    Policy Name

    This specifies the name of this CoS Policy.

    Type

    This specifies the type of queueing algorithm used for this CoS Policy. The types include the following: CBWFQ, MDRR, MDRR strict, MDRR alternate, ERX.

    Status

    This displays the status of the CoS Policy, whether or not it contains CoS classes that do not have a CoS alias defined, or contains multiple CoS classes that are in the same CoS alias. It will show either “Valid” or “Invalid”. To make an invalid policy valid, the user must fix whatever problems exist in the CoS Classes window. The Check button in the CoS Classes window is useful for listing all problems with CoS class definitions.

    Click on the Add button to add a new CoS policy.

    Figure 2: Add CoS Policy Window

    Add CoS Policy Window

    In the previous example there are four defined classes: voice, first_class_data, business_data, and economy_data.

    This window has the following fields:

    Field

    Description

    Router

    This is a drop down menu that lets the user choose one of the existing routers. “[Any router]” means that the policy will be applied to all routers.

    Policy Name

    CoS Policy Name

    Type

    This is a drop down menu that lets the user select the type of queueing algorithm that this CoS policy uses: CBWFQ, MDRR, MDRR strict, MDRR alternate, or HWRR.

    Class

    For each class entry, the user can select the class name to be displayed from the drop down menu. Each drop down menu only contains the class names that have been defined for that particular CoS alias in the CoS Classes window.

    BW (Kbps)

    If the queueing algorithm Type is set to CBWFQ:

    • For the priority class, this is the maximum bandwidth allowed for that class. Packets over that limit are dropped.
    • For other classes, this is the guaranteed minimum bandwidth for the class during congestion. Packets over that limit may be accepted.
    • Default unit is Kbps (Kilobits per second).
    • To specify bandwidth reservation for a CoS policy, you can specify the actual bandwidth (e.g. 3M) or a percentage of the trunk bandwidth (e.g. 30%)
    • You can also specify remaining % of bandwidth not already reserved by other CoS classes using rX%. Example, to specify 100% of remaining BW use r100% and to specify 30% of remaining BW use r30%.

    Note: The total of all the bandwidths defined in the class policies of the policy map must be less than 75% of the capacity of the link.

    Weight

    This field appears in place of the BW field if the type is set to MDRR (strict or alternate). Each MDRR queue can be assigned a relative weight that determines relative bandwidth for each queue when congestion occurs. If no Weight is specified then the default value of 10 is used. The priority class for MDRR strict policies cannot have a weight defined.

    Queue Size (packets)

    The maximum number of packets allowed in the queue for the specified class.

    Note: The priority class has no queue, so the user cannot specify its queue size. Queue sizes for other classes can be specified by the user.

    Note: The maximum allowable value is 64 packets.


    Related Cisco commands:


    At the config level the command used to create policies is:

    Router(config) # policy-map policy-map-name

    Then, a class has to be specified by the following command.

    Router(config-pmap) # class class-name

    The policy is now applied for that class. After the above command, bandwidth and queue-limit can be specified to characterize the class’s queue. The commands to do that are:

    Router(config-pmap-c) # bandwidth bandwidth-kbps
    Router(config-pmap-c) # bandwidth percent percentage
    Router(config-pmap-c) # queue-limit number-of-packets

    Example:


    Router(config) # policy-map policy1
    Router(config-pmap) # class class1
    Router(config-pmap-c) # bandwidth 3000
    Router(config-pmap-c) # queue-limit 30
    Router(config-pmap) # class class2
    Router(config-pmap-c) # bandwidth percent 10

    HWRR Policies


    For HWRR policies, the user is presented with a more advanced policy configuration window. Because ERX HWRR policies can contain multiple levels of scheduler nodes, the user has the ability to define two types of objects in the HWRR policy editor: nodes and queues.

    Figure 3: CoS HWRR Policy Window - Scheduler Nodes

    CoS HWRR Policy Window - Scheduler Nodes

    To Add a Scheduler Node


    1. Select the parent node in the left tree under which the new scheduler node will be added.
    2. Select Scheduler Nodes from the Hierarchy Type dropdown menu.
    3. Enter a name for the new scheduler node into the Scheduler Node column.
    4. (Optional) Enter a Weight for the new scheduler node.
    5. (Optional) Enter a Shaping Rate for the new scheduler node.
    6. Click the Add button to add the new scheduler node.

    Figure 4: CoS HWRR Policy Window - Queues

    CoS HWRR Policy Window - Queues

    To Add a Queue


    1. Select the node in the left tree under which the new queue will be added.
    2. Select Queues from the Hierarchy Type dropdown menu.
    3. Select a class for the new queue from the Class dropdown menu.
    4. (Optional) Enter a Weight for the new queue.
    5. (Optional) Enter a Queue Size for the new queue.
    6. Click OK, or continue editing the policy. The queues are saved automatically.

    Modified: 2016-11-08