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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
Configuring Priority Queueing
This chapter describes the tasks for configuring priority queueing (PQ) on a router.
For complete conceptual information, see the section "Priority Queueing" in the chapter "Congestion Management Overview" in this book.
For a complete description of the PQ commands in this chapter, refer to the Cisco IOS Quality of Service Solutions Command Reference. To locate documentation of other commands that appear in this chapter, use the command reference master index or search online.
To identify the hardware platform or software image information associated with a feature, use the Feature Navigator on Cisco.com to search for information about the feature or refer to the software release notes for a specific release. For more information, see the "Identifying Supported Platforms" section in the "Using Cisco IOS Software" chapter in this book.
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.
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Defining the Priority List (Required)
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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.
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Assigning Packets to Priority Queues
Assign packets to priority queues based on the following qualities:
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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 including byte count, TCP service and port number assignments, and AppleTalk, IP, IPX, VINES, or XNS access list assignments. Refer to 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 10.
Table 10 Default Priority Queue Packet Limits
high-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:
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For information on how to configure PQ, see the section "Priority Queueing Configuration Task List" in this chapter.
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
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:
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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
