Table Of Contents
Priority Queueing Configuration Task List
Assigning Packets to Priority Queues
Specifying the Maximum Size of the Priority Queues
Assigning the Priority List to an Interface
Monitoring Priority Queueing Lists
Priority Queueing Configuration Examples
Priority Queueing Based on Protocol Type: Example
Priority Queueing Based on Interface: Example
Maximum Specified Size of the Priority Queue: Example
Priority List Assigned to an Interface: Example
Priority Queueing Using Multiple Rules: Example
Feature Information for Configuring Priority Queueing
Configuring Priority Queueing
This chapter describes the tasks for configuring priority queueing (PQ) on a router.
For complete conceptual information, see the "Congestion Management Overview" module.
Finding Feature Information
For the latest feature information and caveats, see the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the "Feature Information for Configuring Priority Queueing" section.
Use Cisco Feature Navigator to find information about platform support and Cisco IOS, Catalyst OS, and Cisco IOS XE software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.
Priority Queueing Configuration Task List
To configure PQ, perform the tasks described in the following sections. The tasks in the first two sections are required; the task in remaining section is optional.
•Defining the Priority List (Required)
•Assigning the Priority List to an Interface (Required)
•Monitoring Priority Queueing Lists (Optional)
See the end of this chapter for the section "Priority Queueing Configuration Examples."
Defining the Priority List
A priority list contains the definitions for a set of priority queues. The priority list specifies which queue a packet will be placed in and, optionally, the maximum length of the different queues.
In order to perform queueing using a priority list, you must assign the list to an interface. The same priority list can be applied to multiple interfaces. Alternatively, you can create many different priority policies to apply to different interfaces.
To define a priority list, perform the tasks described in the following sections. The task in the first section is required; the task in the remaining section is optional.
•Assigning Packets to Priority Queues (Required)
•Specifying the Maximum Size of the Priority Queues (Optional)
Assigning Packets to Priority Queues
Assign packets to priority queues based on the following qualities:
•Protocol type
•Interface where the packets enter the router
You can specify multiple assignment rules. The priority-list commands are read in order of appearance until a matching protocol or interface type is found. When a match is found, the packet is assigned to the appropriate queue and the search ends. Packets that do not match other assignment rules are assigned to the default queue.
To specify which queue to place a packet in, use the following commands in global configuration mode:
All protocols supported by Cisco are allowed. The queue-keyword argument provides additional options. See the priority-list protocol command syntax description in the Cisco IOS Quality of Service Solutions Command Reference.
Specifying the Maximum Size of the Priority Queues
To specify the maximum number of packets allowed in each of the priority queues, use the following command in global configuration mode:
Use the priority-list queue-limit command for each priority list. The default queue limit arguments are listed in Table 1.
Table 1 Default Priority Queue Packet Limits
Priority Queue Argument Packet Limitshigh-limit
20
medium-limit
40
normal-limit
60
low-limit
80
Assigning the Priority List to an Interface
You can assign a priority list number to an interface. Only one list can be assigned per interface. To assign a priority group to an interface, use the following commands beginning in global configuration mode:
Monitoring Priority Queueing Lists
To display information about the input and output queues, use the following commands in EXEC mode, as needed:
Priority Queueing Configuration Examples
The following sections provide PQ configuration examples:
•Priority Queueing Based on Protocol Type: Example
•Priority Queueing Based on Interface: Example
•Maximum Specified Size of the Priority Queue: Example
•Priority List Assigned to an Interface: Example
•Priority Queueing Using Multiple Rules: Example
For information on how to configure PQ, see the section "Priority Queueing Configuration Task List" in this module.
Priority Queueing Based on Protocol Type: Example
The following example establishes queueing based on protocol type. The example assigns 1 as the arbitrary priority list number, specifies IP as the protocol type, and assigns a high priority level to traffic that matches IP access list 10.
access-list 10 permit 239.1.1.0 0.0.0.255priority-list 1 protocol ip high list 10Priority Queueing Based on Interface: Example
The following example establishes queueing based on interface. The example sets any packet type entering on Ethernet interface 0 to a medium priority.
priority-list 3 interface ethernet 0 mediumMaximum Specified Size of the Priority Queue: Example
The following example changes the maximum number of packets in the high priority queue to 10. The medium-limit, normal, and low-limit queue sizes remain at their default 40-, 60-, and 80-packet limits.
priority-list 4 queue-limit 10 40 60 80Priority List Assigned to an Interface: Example
The following example assigns priority group list 4 to serial interface 0:
interface serial 0priority-group 4
Note The priority-group list-number command is not available on ATM interfaces that do not support fancy queueing.
Priority Queueing Using Multiple Rules: Example
When classifying a packet, the system searches the list of rules specified by priority-list commands for a matching protocol type. The following example specifies four rules:
•DECnet packets with a byte count less than 200 are assigned a medium priority queue level.
•IP packets originating or destined to TCP port 23 are assigned a medium priority queue level.
•IP packets originating or destined to User Datagram Protocol (UDP) port 53 are assigned a medium priority queue level.
•All IP packets are assigned a high priority queue level.
Remember that when using multiple rules for a single protocol, the system reads the priority settings in the order of appearance.
priority-list 4 protocol decnet medium lt 200priority-list 4 protocol ip medium tcp 23priority-list 4 protocol ip medium udp 53priority-list 4 protocol ip high
Feature Information for Configuring Priority Queueing
Table 2 lists the features in this module and provides links to specific configuration information.
Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which Cisco IOS XE software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.
Note Table 2 lists only the Cisco IOS XE software release that introduced support for a given feature in a given Cisco IOS XE software release train. Unless noted otherwise, subsequent releases of that Cisco IOS XE software release train also support that feature.
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