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This chapter describes how to configure the QoS priority queuing feature on the Cisco 1000 Series Connected Grid Router (hereafter referred to as the Cisco CG-OS router). This chapter includes the following sections:
•Information About Priority Queuing
•Prerequisites for Priority Queuing
•Verifying the Priority Queuing Configuration
The Cisco CG-OS router employs priority queuing to manage the flow of traffic within the network and to achieve throughput and latency targets. Priority queuing employs index values, which you assign to class-maps to determine the order in which the Cisco CG-OS router forwards the associated packets.
You can only assign priority queue indexes to Layer 3 interfaces that are QoS classified or marked. Table 5-1 lists the Layer 3 interfaces supported on the Cisco CG-OS router.
The Cisco CG-OS router supports four priority queue settings for QoS, indexes 1 to 4, where 1 is the highest priority and 4 is the lowest. The Cisco CG-OS router sends outgoing traffic for each Layer 3 interface (see Table 5-1) based on its assigned priority queue index (see Table 5-2). You can assign these priority queue levels to traffic classes (class maps) to manage the sequencing of packets to yield a more consistent flow of traffic within the network.
For example, the Cisco CG-OS router forwards all outgoing traffic with a priority queue index of one, the highest priority setting, before forwarding any outgoing traffic with a priority queue index of 2. Likewise, the Cisco CG-OS router forwards all traffic with a priority queue index of 2 before traffic with a priority queue index of 3. This pattern continues until the Cisco CG-OS router forwards traffic from the lowest priority queue (4), which has an index of 4.
When the queue buffer overloads, the Cisco CG-OS router drops packets.
You must be familiar with Chapter 2 "Using Modular QoS CLI."
You are logged on to the Cisco CG-OS router.
Configure system-defined class maps with care because the changes occur immediately and traffic might be disrupted.
You configure priority queuing by creating policy maps of type qos that you can apply to outgoing (egress) traffic on an interface. You can modify system-defined class maps, which are used in policy maps to define classes of traffic to which you want to apply policies. For information about configuring policy maps and class maps, see Chapter 2 "Using Modular QoS CLI."
This section includes the following topics:
•Assigning Priority Queues to Layer 3 Interfaces
Configure the policy map. See Configuring or Modifying a Policy Map.
Configure the class map. See Configuring or Modifying a Class Map.
This example shows how to configure a priority queue index of 2 for the type qos class map, priority_queuing2:
router# configure terminal
router(config)# policy-map type qos priority_queuing2
router(config-pmap-qos)# class type_queuing
router(config-pmap-c-qos)# priority level 2
router(config-pmap-c-qos)# copy running-config startup-config
You can assign a priority queue index to Layer 3 interfaces. Table 5-1 lists supported interfaces.
Configure the priority queue. See Configuring Priority Queuing.
This example shows how to configure a priority queue of level 2 for a specific queue:
router# configure terminal
router(config)# interface cellular 3/1
router(config-if)# service-policy output priority_queuing2
router(config-if)# copy running-config startup-config
Note For details on how to view QoS statistics on the interfaces, see Chapter 6 "Monitoring QoS Statistics."
To verify the QoS priority queuing configuration, enter the following command:
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show policy-map type qos [policy-map-name] |
(Optional) Displays information about all configured policy maps or a selected policy map of type qos. |