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This chapter describes the tasks for configuring QoS custom queueing (CQ) on a router.
For complete conceptual information, see the section "Custom Queueing" in the chapter "Congestion Management Overview" in this book.
For a complete description of the CQ 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.
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Note Custom queueing is not supported on any tunnels. |
You must follow certain required, basic steps to enable custom queueing for your network. In addition, you can choose to assign packets to custom queues based on protocol type, interface where the packets enter the router, or other criteria you specify.
To configure CQ, perform the tasks in the following sections. The first and third sections are required; the remaining sections are optional.
See the end of this chapter for the section "Custom Queueing Configuration Examples."
To assign a custom queue list to an interface, use the following commands beginning in global configuration mode:
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Note Use the custom-queue-list command in place of the priority-list command. Only one queue list can be assigned per interface. |
Custom queueing allows a fairness not provided with priority queueing. With custom queueing, you can control the available bandwidth on an interface when it is unable to accommodate the aggregate traffic enqueued. Associated with each output queue is a configurable byte count, which specifies how many bytes of data should be delivered from the current queue by the system before the system moves on to the next queue. When a particular queue is being processed, packets are sent until the number of bytes sent exceeds the queue byte count defined by the queue-list queue byte-count command (see the following section, "Specifying the Maximum Size of the Custom Queues"), or until the queue is empty.
You can specify the maximum number of packets allowed in each of the custom queues. The default is 20 entries.
You can also specify the approximate number of bytes to be forwarded from each queue during its turn in the cycle. The number is used as an average number, because whole packets must be forwarded.
To specify the approximate number of bytes to be forwarded from each queue during its turn in the cycle, use one of the following commands in global configuration mode:
| Command | Purpose |
|---|---|
queue-list list-number queue queue-number limit limit-number | Specifies the maximum number of packets allowed in each of the custom queues. The limit-number argument specifies the number of packets that can be enqueued at any one time. The range is 0 to 32767. |
queue-list list-number queue queue-number byte-count byte-count-number | Designates the average number of bytes forwarded per queue. The byte-count-number argument specifies the average number of bytes the system allows to be delivered from a given queue during a particular cycle. |
You can assign packets to custom queues based on the protocol type or interface where the packets enter the router. Additionally, you can set the default queue for packets that do not match other assignment rules. You can also specify multiple rules.
To define the custom queueing lists, use one of the following commands in global configuration mode:
| Command | Purpose |
|---|---|
queue-list list-number protocol protocol-name queue-number queue-keyword keyword-value | Establishes queueing priorities based on the protocol type. |
queue-list list-number interface interface-type interface-number queue-number | Establishes custom queueing based on packets entering from a given interface. |
queue-list list-number default queue-number | Assigns a queue number for those packets that do not match any other rule in the custom queue list. |
All protocols supported by Cisco are allowed. The queue-keyword variable provides additional options, including byte count, TCP service and port number assignments, and AppleTalk, IP, IPX, VINES, or XNS access list assignments. See the queue-list protocol command syntax description in the Cisco IOS Quality of Service Solutions Command Reference.
When you use multiple rules, remember that the system reads the queue-list commands in order of appearance. When classifying a packet, the system searches the list of rules specified by queue-list commands for a matching protocol or interface type. When a match is found, the packet is assigned to the appropriate queue. The list is searched in the order it is specified, and the first matching rule terminates the search.
To show information about the input and output queues when custom queueing is enabled on an interface, use one or more of the following commands in EXEC mode:
| Command | Purpose |
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show queue interface-type interface-number | Displays the contents of packets inside a queue for a particular interface or VC. |
show queueing custom | Displays the status of the custom queueing lists. |
show interfaces interface-type interface-number | Displays the current status of the custom output queues when custom queueing is enabled. |
The following sections provide custom queueing examples:
For information on how to configure CQ, see the section "Custom Queueing Configuration Task List" earlier in this chapter.
The following example illustrates how to assign custom queue list number 3 to serial interface 0:
interface serial 0 custom-queue-list 3
The following example specifies the maximum number of packets allowed in each custom queue. The queue length of queue 10 is increased from the default 20 packets to 40 packets.
queue-list 3 queue 10 limit 40
The queue length limit is the maximum number of packets that can be enqueued at any time, with the range being 0 to 32767 queue entries.
The following example decreases queue list 9 from the default byte count of 1500 to 1400 for queue number 10:
queue-list 9 queue 10 byte-count 1400
The byte count establishes the lowest number of bytes the system allows to be delivered from a given queue during a particular cycle.
The following examples assign packets to custom queues by either protocol type or interface type, and the default assignment for unmatched packets.
The following example assigns traffic that matches IP access list 10 to queue number 1:
queue-list 1 protocol ip 1 list 10
The following example assigns Telnet packets to queue number 2:
queue-list 4 protocol ip 2 tcp 23
The following example assigns UDP Domain Name Service (DNS) packets to queue number 3:
queue-list 4 protocol ip 3 udp 53
In this example, queue list 4 establishes queueing priorities for packets entering on serial interface 0. The queue number assigned is 10.
queue-list 4 interface serial 0 10
You can define multiple rules; the system reads the priority settings in order of appearance. The system searches the list in the order it is specified, and the first matching rule terminates the search. When a match is found, the packet is assigned to the appropriate queue.
You can specify a default queue for packets that do not match other assignment rules. In this example, the default queue for list 10 is set to queue number 2.
queue-list 10 default 2
Posted: Mon Aug 21 21:25:50 PDT 2000
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