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Table of Contents

Quality of Service Commands

Quality of Service Commands

Use the commands in this chapter to configure quality of service (QoS), a measure of performance for a transmission system that reflects its transmission quality and service availability. The commands are arranged alphabetically.

For QoS configuration information and examples, refer to the Quality of Service Solutions Configuration Guide.

access-list rate-limit

To configure an access list for use with committed access rate (CAR) policies, use the access-list rate-limit global configuration command. To remove the access list from the configuration, use the no form of this command.

access-list rate-limit acl-index {precedence | mac-address | mask prec-mask}
no access-list rate-limit acl-index {precedence | mac-address | mask prec-mask}

Syntax Description

acl-index

Access list number. Use any number from 1 to 99 to classify packets by precedence or precedence mask, and use any number from 100 to 199 to classify by MAC address.

precedence

IP precedence.

mac-address

Address of the MAC.

mask prec-mask

IP precedence mask; a two-digit hexadecimal number. Use this option when you want to assign multiple precedences to the same rate-limit access list.

Default

No CAR access lists are configured.

Command Mode

Global configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 11.1 CC.

This command classifies packets by the specified IP precedence or MAC address for a particular CAR access list. You can then apply CAR policies, using the rate-limit command, to individual rate limit access lists. Thus, packets with different IP precedences or MAC addresses are treated differently by the CAR process.

You can specify only one command for each rate limit access list. If you enter this command multiple times with the same access list number, the new command will overwrite the previous command.

Use the mask keyword to assign multiple IP precedences to the same rate-limit list. To determine the mask value, perform the following steps:

Step 1 Decide which precedences you want to assign to this rate-limit access list.

Step 2 Convert the precedences into an 8-bit number with each bit corresponding to one precedence. For example, an IP precedence of 0 corresponds to 00000001, 1 corresponds to 00000010, 6 corresponds to 01000000, and 7 corresponds to 10000000.

Step 3 Add the 8-bit numbers for the selected precedences. For example, the mask for precedences 1 and 6 is 01000010.

Step 4 The command expects hexadecimal format. Convert the binary mask into the corresponding hexadecimal number. For example, 01000010 becomes 42. This value is used in the access-list rate-limit command. Any packets that have an IP precedence of 1 or 6 will match this access list.

A mask of FF matches any precedence, and 00 does not match any precedence.

Examples

The following example assigns any packets with a MAC address of 00e0.34b0.7777 to rate-limit access list 100:

router(config)# access-list rate-limit 100 00e0.34b0.7777
 

The following example assigns packets with an IP precedence of 0, 1, or 2 to the rate-limit access list 25:

router(config)# access-list rate-limit 25 mask 42
 

Related Commands

You can use the master indexes or search online to find documentation of related commands.

show access-lists rate-limit
show ip cef

bgp-policy

To enable Policy Propagation via Border Gateway Protocol (BGP) on the interface, use the bgp-policy interface configuration command. To disable Policy Propagation via BGP, use the no form of this command.

bgp-policy ip-prec-map
no bgp-policy
ip-prec-map

Syntax Description

ip-prec-map

QoS policy based on the IP precedence.

Default

Policy Propagation via BGP is disabled.

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 11.1 CC.

For the Policy Propagation via BGP feature to work, you must enable BGP and CEF/DCEF. In addition, the proper route-map configuration must be in place to specify the IP precedence (for example, set ip precedence route-map configuration command).


Note If you specify both source and destination on the interface, the software looks up the source address in the routing table and classifies the packet based on the source address first; then the software looks up the destination address in the routing table and reclassifies the packet based on the destination address.

To display QoS policy information for the interface, use the show ip interface command.

Example

The following example enables Policy Propagation via BGP on an interface based on the source address and the IP precedence setting:

router# configure terminal
router(config)# interface ethernet 4/0/0
router(config-if)# bgp-policy ip-prec-map
router(config-if)# end
router#

custom-queue-list

To assign a custom queue list to an interface, use the custom-queue-list interface configuration command. To remove a specific list or all list assignments, use the no form of the command.

custom-queue-list list
no custom-queue-list [list]

Syntax Description

list

Any number from 1 to 16 for the custom queue list.

Default

No custom queue list is assigned.

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

Only one queue list can be assigned per interface. Use this command in place of the priority-list command (not in addition to it). Custom queueing allows a fairness not provided with priority queueing. With custom queueing, you can control the interface's available bandwidth 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 or until the queue is empty.

Use the show queueing custom and show interface commands to display the current status of the custom output queues.

Example

In the following example, custom queue list number 3 is assigned to serial interface 0:

router(config)# interface serial 0
router(config-if)# custom-queue-list 3

Related Commands

You can use the master indexes or search online to find documentation of related commands.

queue-list default
queue-list interface
queue-list queue byte-count
queue-list queue limit
show interfaces
show queue
show queueing

fair-queue

To enable weighted fair queueing (WFQ) for an interface, use the fair-queue interface configuration command. To disable weighted fair queueing for an interface, use the no form of this command.

fair-queue [congestive-discard-threshold [dynamic-queues [reservable-queues]]]
no fair-queue

Syntax Description

congestive-discard-threshold

(Optional) Number of messages allowed in each queue. The default is 64 messages, and a new threshold must be a power of 2 in the range 16 to 4096. When a conversation reaches this threshold, new message packets are discarded.

dynamic-queues

(Optional) Number of dynamic queues used for best-effort conversations (that is, a normal conversation not requiring any special network services). Values are 16, 32, 64, 128, 256, 512, 1024, 2048, and 4096. The default is 256.

reservable-queues

(Optional) Number of reservable queues used for reserved conversations in the range 0 to 1000. The default is 0. Reservable queues are used for interfaces configured for features such as Resource Reservation Protocol (RSVP).

Default

Fair queueing is enabled by default for physical interfaces whose bandwidth is less than or equal to 2.048 Mbps and that do not use the following: X.25 and Synchronous Data Link Control (SDLC) encapsulations; Link Access Procedure, Balanced (LAPB); tunnels; loopbacks; dialer; bridges; or virtual interfaces. Fair queueing is not an option for these protocols. However, if custom queueing or priority queueing is enabled for a qualifying link, it overrides fair queueing, effectively disabling it. Additionally, fair queueing is automatically disabled if you enable the autonomous or silicon switching engine mechanisms. Fair queueing is also enabled automatically on interfaces configured for Multilink PPP.

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 11.0.

The command enables WFQ. With WFQ, packets are classified by flow. For example, packets with the same source IP address, destination IP address, source TCP or UDP port, destination TCP or UDP port, protocol, and type of service (ToS) field belong to the same flow; see Table 3 for a full list of protocols and traffic stream discrimination fields.

When enabled for an interface, WFQ provides traffic priority management that automatically sorts among individual traffic streams without requiring that you first define access lists. Enabling WFQ requires use of this command only.

When WFQ is enabled for an interface, new messages for high-bandwidth traffic streams are discarded after the configured or default congestive discard threshold has been met. However, low-bandwidth conversations, which include control message conversations, continue to enqueue data. As a result, the fair queue may occasionally contain more messages than its configured threshold number specifies.

WFQ uses a traffic data stream discrimination registry service to determine which traffic stream a message belongs to. For each forwarding protocol, Table 3 shows the attributes of a message that are used to classify traffic into data streams.


Table 3: Weighted Fair Queueing Traffic Stream Discrimination Fields
Forwarder Fields Used

AppleTalk

  • Source net, node, socket

  • Destination net, node, socket

  • Type

CLNS

  • Source NSAP

  • Destination NSAP

DECnet

  • Source address

  • Destination address

Frame Relay switching

  • DLCI value

IP

  • ToS

  • IP protocol

  • Source IP address (if message is not fragmented)

  • Destination IP address (if message is not fragmented)

  • Source TCP/UDP port

  • Destination TCP/UDP port

Transparent bridging

  • Unicast: source MAC, destination MAC

  • Ethertype SAP/SNAP multicast: destination MAC address

Source-route bridging

  • Unicast: source MAC, destination MAC

  • SAP/SNAP multicast: destination MAC address

VINES

  • Source network/host

  • Destination network/host

  • Level 2 protocol

Apollo

  • Source network/host/socket

  • Destination network/host/socket

  • Level 2 protocol

XNS

  • Source/destination network/host/socket

  • Level 2 protocol

Novell NetWare

  • Source/destination network/host/socket

  • Level 2 protocol

All others (default)

  • Control protocols (one queue per protocol)

It is important to note that IP precedence, congestion in Frame Relay switching, and discard eligibility flags affect the weights used for queueing.

IP precedence, which is set by the host or by policy maps, is a number in the range of 0 to 7. Data streams of precedence number are weighted so that they are given an effective bit rate of number+1 times as fast as a data stream of precedence 0, which is normal.

In Frame Relay switching, message flags for forward explicit congestion notification (FECN), backward explicit congestion notification (BECN), and discard eligibility (DE) message flags cause the algorithm to select weights that effectively impose reduced queue priority, providing the application with "slow down" feedback and sorting traffic, giving the best service to applications within their committed information rate (CIR).

Fair queueing is supported for all LAN and line (WAN) protocols except X.25, including LAPB and SDLC; see the notes in the section "Default." Because tunnels are software interfaces that are themselves routed over physical interfaces, fair queueing is not supported for tunnels. Fair queueing is on by default for interfaces with bandwidth less than or equal to 2 Mbps.


Note For Release 10.3 and earlier for the Cisco 7000 and 7500 routers with an RSP card, if you used the tx-queue-limit command to set the transmit limit available to an interface on an MCI or SCI card and you configured custom queueing or priority queueing for that interface, the configured transmit limit was automatically overridden and set to 1. With Cisco IOS Release 12.0, for weighted fair queueing, custom queueing, and priority queueing, the configured transmit limit is derived from the bandwidth value set for the interface using the bandwidth command. Bandwidth value divided by 512 rounded up yields the effective transmit limit. However, the derived value only applies in the absence of a tx-queue-limit command; that is, a configured transmit limit overrides this derivation.

When Resource Reservation Protocol (RSVP) is configured on an interface that supports fair queueing or on an interface that is configured for fair queueing with the reservable queues set to 0 (the default), the reservable queue size is automatically configured using the following method: interface bandwidth divided by 32 kbps. You can override this default by specifying a reservable queue other than 0. For more information on RSVP, refer to the chapter "Configuring RSVP" in the Network Protocols Configuration Guide, Part 1.

Examples

The following example enables use of WFQ on serial interface 0, with a congestive threshold of 300. This threshold means that messages will be discarded from the queueing system only when 300 or more messages have been queued and the message is in a data stream that has more than one message in the queue. The transmit queue limit is set to 2, based on the 384-kilobit (Kb) line set by the bandwidth command:

router(config)# interface serial 0
router(config-if)# bandwidth 384
router(config-if)# fair-queue 300

Unspecified parameters take the default values.

The following example requests a fair queue with a congestive discard threshold of 64 messages,
512 dynamic queues, and 18 RSVP queues:

router(config)# interface Serial 3/0
router(config-if)# ip unnumbered Ethernet 0/0
router(config-if)# fair-queue 64 512 18

Related Commands

You can use the master indexes or search online to find documentation of related commands.

custom-queue-list
priority-group
priority-list default
show interfaces
show queue
show queueing

fair-queue (DWFQ)

To enable distributed weighted fair queueing (DWFQ), use the fair-queue interface configuration command. The command enables DWFQ on an interface using a VIP2-40 or greater interface processor. To disable DWFQ, use the no form of this command.

fair-queue
no fair-queue

Syntax Description

This command has no arguments or keywords.

Default

DWFQ is enabled by default for physical interfaces whose bandwidth is less than or equal to
2.048 Mbps.

DWFQ can be configured on interfaces but not subinterfaces. It is not supported on Fast EtherChannel, tunnel, or other logical or virtual interfaces such as Multilink Point-to-Point Protocol.

Table 4 lists the default queue lengths and thresholds.


Table 4: Default Fair Queues and Thresholds
Queue or Threshold Default

Congestive discard threshold

64 messages

Dynamic queues

256

Reservable queues

0

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 11.1.

With DWFQ, packets are classified by flow. Packets with the same source IP address, destination IP address, source TCP or UDP port, destination TCP or UDP port, protocol, and type of service (ToS) field belong to the same flow.

DWFQ allocates an equal share of the bandwidth to each flow.

Example

The following example enables DWFQ on the HSSI 0/0/0 interface:

router(config)# interface Hssi0/0/0
router(config-if)# description 45Mbps to R2
router(config-if)# ip address 200.200.14.250 255.255.255.252
router(config-if)# fair-queue

Related Commands

show interfaces
show interfaces fair-queue

ip rsvp bandwidth

To enable RSVP for IP on an interface, use the ip rsvp bandwidth interface configuration command. To disable RSVP, use the no form of the command.

ip rsvp bandwidth [interface-kbps [single-flow-kbps]]
no ip rsvp bandwidth [interface-kbps [single-flow-kbps]]

Syntax Description

interface-kbps

(Optional) Amount of bandwidth (in kbps) on interface to be reserved. The range is 1 to 10000000.

single-flow-kbps

(Optional) Amount of bandwidth (in kbps) allocated to a single flow. The range is 1 to 10000000.

Default

RSVP is disabled if this command is not entered. When enabled without the optional arguments, RSVP is enabled on 75 percent of the link bandwidth.

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 11.2.

This command is not supported on VIP-based routers. RSVP is disabled by default to allow backward compatibility with systems that do not implement RSVP. Weighted Random Early Detection (WRED) or fair queueing must be enabled first.

Example

The following example shows a T1 (1536 kbps) link configured to permit RSVP reservation of up to 1158 kbps, but no more than 100 kbps for any given flow on serial interface 0. Fair queueing is configured with 15 reservable queues to support those reserved flows, should they be required.

router(config)# interface serial 0
router(config-if)# fair-queue 64 256 15 router(config-if)# ip rsvp bandwidth 1158 100

Related Commands

You can use the master indexes or search online to find documentation of related commands.

fair-queue
ip rsvp neighbors
ip rsvp reservation
ip rsvp sender
ip rsvp udp-multicast
random-detect
show ip rsvp installed
show ip rsvp interface
show ip rsvp neighbor
show ip rsvp reservation
show ip rsvp sender

ip rsvp neighbors

To enable neighbors to request a reservation, use the ip rsvp neighbors interface configuration command. To disable this feature, use the no form of the command.

ip rsvp neighbors access-list-number
no ip rsvp neighbors access-list-number

Syntax Description

access-list-number

Number of a standard or extended access list. It can be any number from 1 to 199.

Default

The router accepts messages from any neighbor.

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 11.2.

This command is not supported on VIP-based routers. Use this command to allow only specific RSVP neighbors to make a reservation. If no limits are specified, any neighbor can request a reservation. If an access list is specified, only neighbors meeting the specified access list requirements can make a reservation.

Example

The following example allows neighbors meeting access list 1 requirements to request a reservation:

router(config)# interface ethernet 0
router(config-if)# ip rsvp neighbors 1

Related Commands

You can use the master indexes or search online to find documentation of related commands.

fair-queue
ip rsvp bandwidth
ip rsvp reservation
ip rsvp sender
ip rsvp udp-multicast
random-detect
show ip rsvp installed
show ip rsvp interface
show ip rsvp neighbor
show ip rsvp reservation
show ip rsvp sender

ip rsvp reservation

To enable a router to generate an RSVP RESV message, use the ip rsvp reservation interface configuration command. To disable this feature, use the no form of the command.

ip rsvp reservation session-ip-address sender-ip-address {tcp | udp | ip-protocol}
session-dport sender-sport next-hop-ip-address next-hop-interface {ff | se | wf}
{rate | load} [bandwidth [burst-size]]
no ip rsvp reservation session-ip-address sender-ip-address {tcp | udp | ip-protocol}
session-dport sender-sport next-hop-ip-address next-hop-interface {ff | se | wf}
{rate | load} [bandwidth [burst-size]]

Syntax Description

session-ip-address

For unicast sessions, this is the address of the intended receiver; for multicast sessions, it is the IP multicast address of the session.

sender-ip-address

The IP address of the sender.

tcp | udp | ip-protocol

TCP, UDP, or IP protocol in the range 0 to 255.

session-dport
sender-sport

Session-dport is the destination port. Sender-sport is the source port. Port numbers are specified in all cases, as the use of 16-bit ports following the IP header is not limited to UDP or TCP. If destination is zero, source must be zero, and the implication is that ports are not checked. If destination is nonzero, source must be nonzero.

next-hop-ip-address

Host name or address of the receiver or the router closest to the receiver.

next-hop-interface

Next hop interface or subinterface type and number. Interface type can be ethernet, loopback, null, or serial.

ff | se | wf

Reservation style:

Fixed Filter (ff) is single reservation.

Shared Explicit (se) is shared reservation, limited scope.

Wild Card Filter (wf) is shared reservation, unlimited scope.

rate | load

QoS guaranteed bit rate service or controlled load service.

bandwidth

(Optional) Average bit rate (kbps) to reserve up to 75 percent of total on interface. The range is 1 to 10000000.

burst-size

(Optional) Maximum burst size (kilobytes of data in queue). The range is 1 to 65535.

Default

The router does not simulate receiving an RSVP RESV message by default.

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 11.2.

Use this command to force the router to act like it is generating RSVP RESV messages from the receiver.

This command is not supported on VIP-based routers.

Examples

The following example specifies the use of a Shared Explicit Filter style of reservation and the Controlled Load Service, with token buckets of 100 or 150 kbps and 60 or 65 kbps maximum queue depth:

router(config)# interface ethernet 0
router(config-if)# ip rsvp reservation 224.250.0.2 132.240.1.1 UDP 20 30 132.240.4.1 Et1 se load 100 60
router(config-if)# ip rsvp reservation 224.250.0.2 132.240.2.1 TCP 20 30 132.240.4.1 Et1 se load 150 65
 

The following example specifies the use of a Wild Card Filter style of reservation and the Guaranteed Bit Rate Service, with token buckets of 300 or 350 kbps and 60 or 65 kbps maximum queue depth:

router(config)# interface ethernet 0
router(config-if)# ip rsvp reservation 224.250.0.3 0.0.0.0 UDP 20 0 132.240.4.1  Et1 wf rate 300 60
router(config-if)# ip rsvp reservation 224.250.0.3 0.0.0.0 UDP 20 0 132.240.4.1  Et1 wf rate 350 65
 

Note that the Wild Card Filter does not admit the specification of the sender; it accepts all senders. This action is denoted by setting the source address and port to zero. If, in any filter style, the destination port is specified to be zero, RSVP does not permit the source port to be anything else; it understands that such protocols do not use ports or that the specification applies to all ports.

Related Commands

You can use the master indexes or search online to find documentation of related commands.

fair-queue
ip rsvp bandwidth
ip rsvp neighbors
ip rsvp sender
ip rsvp udp-multicast
random-detect
show ip rsvp installed
show ip rsvp interface
show ip rsvp neighbor
show ip rsvp reservation
show ip rsvp sender

ip rsvp sender

To enable a router to generate an RSVP PATH message, use the ip rsvp sender interface configuration command. To disable this feature, use the no form of the command.

ip rsvp sender session-ip-address sender-ip-address {tcp | udp | ip-protocol} session-dport
sender-sport previous-hop-ip-address previous-hop-interface
[bandwidth] [burst-size]
no ip rsvp sender session-ip-address sender-ip-address {tcp | udp | ip-protocol} session-dport
sender-sport previous-hop-ip-address previous-hop-interface
[bandwidth] [burst-size]

Syntax Description

session-ip-address

For unicast sessions, this is the address of the intended receiver; for multicast sessions, it is the IP multicast address of the session.

sender-ip-address

The IP address of the sender.

tcp | udp | ip-protocol

TCP, UDP, or IP protocol in the range 0 to 255.

session-dport sender-sport

Session-dport is the destination port. Sender-sport is the source port. Port numbers are specified in all cases, as the use of 16-bit ports following the IP header is not limited to UDP or TCP. If destination is zero, source must be zero, and the implication is that ports are not checked. If destination is nonzero, source must be nonzero.

previous-hop-ip-address

Address of the sender or the router closest to the sender.

previous-hop-interface

Address of the previous hop interface or subinterface. Interface type can be ethernet, loopback, null, or serial.

bandwidth

(Optional) Average bit rate (kbps) to reserve up to 75 percent of total on interface. The range is 1 to 10000000.

burst-size

(Optional) Maximum burst size (kilobytes of data in queue). The range is 1 to 65535.

Default

The router does not simulate RSVP PATH message generation by default.

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 11.2.

Use this command to force the router to act like it is receiving RSVP PATH messages from the sender.

This command is not supported on VIP-based routers.

Example

The following example sets up the router to act like it is receiving RSVP PATH messages using UDP over the loopback 1 interface:

router(config)# interface ethernet 0
router(config-if)# ip rsvp sender 224.250.0.1 132.240.2.1 udp 20 30 132.240.2.1 loopback 1 50 5
router(config-if)# ip rsvp sender 224.250.0.2 132.240.2.1 udp 20 30 132.240.2.1 loopback 1 50 5
router(config-if)# ip rsvp sender 224.250.0.2 132.240.2.28 udp 20 30 132.240.2.28 loopback 1 50 5

Related Commands

You can use the master indexes or search online to find documentation of related commands.

fair-queue
ip rsvp bandwidth
ip rsvp neighbors
ip rsvp reservation
ip rsvp udp-multicast
random-detect
show ip rsvp installed
show ip rsvp interface
show ip rsvp neighbor
show ip rsvp reservation
show ip rsvp sender

ip rsvp udp-multicast

To instruct the router to generate UDP-encapsulated RSVP multicasts whenever it generates an IP-encapsulated multicast packet, use the ip rsvp udp-multicast interface configuration command. To disable this feature, use the no form of the command.

ip rsvp udp-multicast [multicast-address]
no ip rsvp udp-multicast [multicast-address]

Syntax Description

multicast-address

(Optional) Host name or UDP multicast address of router.

Default

The generation of UDP multicasts is disabled. If a system sends a UDP-encapsulated RSVP message to the router, the router starts using UDP for contact with the neighboring system. The router uses multicast address 224.0.0.14 and starts sending to UDP port 1699. If the command is entered without specifying a multicast address, the router uses the same multicast address.

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 11.2.

Use this command to instruct a router to generate UDP-encapsulated RSVP multicasts whenever it generates an IP-encapsulated multicast packet. Some hosts require this trigger from the router.

Example

The following example reserves up to 7500 kbps on Ethernet interface 2, with up to 1 Mbps per flow. The router is configured to use UDP encapsulation with the multicast address 224.0.0.14.

router(config)# interface ethernet 2
router(config-if)# ip rsvp bandwidth 7500 1000
router(config-if)# ip rsvp udp-multicast 224.0.0.14

Related Commands

You can use the master indexes or search online to find documentation of related commands.

ip rsvp bandwidth
ip rsvp neighbors
ip rsvp reservation
ip rsvp sender

priority-group

To assign the specified priority list to an interface, use the priority-group interface configuration command. To remove the specified priority group assignment, use the no form of this command.

priority-group list-number
no priority-group

Syntax Description

list-number

Priority list number assigned to the interface. Any number from 1 to 16.

Default

This command is not enabled by default.

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

Only one list can be assigned per interface. Priority output queueing provides a mechanism to prioritize packets transmitted on an interface.

Use the show queueing priority and show interface commands to display the current status of the output queues.

Example

The following example causes packets for transmission on serial interface 0 to be classified by priority list 1:

router(config)# interface serial 0
router(config-if)# priority-group 1

Related Commands

You can use the master indexes or search online to find documentation of related commands.

priority-list default
priority-list interface
priority-list protocol
priority-list queue-limit

show interfaces
show queue
show queueing

priority-list default

To assign a priority queue for those packets that do not match any other rule in the priority list, use the priority-list default global configuration command. To return to the default or assign normal as the default, use the no form of this command.

priority-list list-number default {high | medium | normal | low}
no priority-list list-number

Syntax Description

list-number

Any number from 1 to 16 that identifies the priority list.

high | medium | normal | low

Priority queue level.

Default

The normal queue, if you use the no form of the command.

Command Mode

Global configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

When you use multiple rules, remember that the system reads the priority settings in order of appearance. When classifying a packet, the system searches the list of rules specified by priority-list commands for a matching protocol or interface type. When a match is found, the system assigns the packet to the appropriate queue. The system searches the list in the order it is specified, and the first matching rule terminates the search.

Example

The following example sets the priority queue for those packets that do not match any other rule in the priority list to a low priority:

router(config)# priority-list 1 default low

Related Commands

You can use the master indexes or search online to find documentation of related commands.

priority-group
priority-list interface
priority-list protocol
priority-list queue-limit
show queue
show queueing

priority-list interface

To establish queueing priorities on packets entering from a given interface, use the priority-list interface global configuration command. To remove an entry from the list, use the no form of this command with the appropriate arguments.

priority-list list-number interface interface-type interface-number {high | medium |
normal | low}
no priority-list list-number

Syntax Description

list-number

Arbitrary integer from 1 to 16 that identifies the priority list selected by the user.

interface-type

The name of the interface.

interface-number

The number of the interface.

high | medium | normal | low

Priority queue level.

Default

No queueing priorities are established.

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

When you use multiple rules, remember that the system reads the priority settings in order of appearance. When classifying a packet, the system searches the list of rules specified by priority-list commands for a matching protocol or interface type. When a match is found, the system assigns the packet to the appropriate queue. The system searches the list in the order it is specified, and the first matching rule terminates the search.

Example

The following example assigns a list entering on serial interface 0 to a medium priority queue level:

router(config)# interface serial 0
router(config-if)# priority-list 3 interface serial 0 medium

Note These commands define a rule that determines how packets are attached to an interface. Once the rule is defined, the packet is actually attached to the interface using the priority-group command.

Related Commands

You can use the master indexes or search online to find documentation of related commands.

priority-group
priority-list default
priority-list protocol
priority-list queue-limit
show queue
show queueing

priority-list protocol

To establish queueing priorities based upon the protocol type, use the priority-list protocol global configuration command. To remove a priority list entry assigned by protocol type, use the no form of the command followed by the appropriate list-number argument and the protocol keyword.

priority-list list-number protocol protocol-name {high | medium | normal | low}
queue-keyword keyword-value
no priority-list list-number protocol [protocol-name {high | medium | normal | low}
queue-keyword keyword-value]

Syntax Description

list-number

Any number from 1 to 16 that identifies the priority list selected by the user.

protocol-name

Protocol type: aarp, apollo, appletalk, arp, bridge (transparent), clns, clns_es, clns_is, compressedtcp, cmns, decnet, decnet_node, decnet_router-l1, decnet_router-l2, dlsw, ip, ipx, pad, rsrb, stun, vines, xns, and x25.

high | medium | normal | low

Priority queue level.

queue-keyword keyword-value

Possible keywords are fragments, gt, list, lt, tcp, and udp. See Table 5.

Default

No queueing priorities are established.

Command Mode

Global configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

When you use multiple rules for a single protocol, remember that the system reads the priority settings in order of appearance. When classifying a packet, the system searches the list of rules specified by priority-list commands for a matching protocol type. When a match is found, the system assigns the packet to the appropriate queue. The system searches the list in the order it is specified, and the first matching rule terminates the search.

The decnet_router-l1 keyword refers to the multicast address for all level 1 routers, which are intra-area routers, and the decnet_router-l2 keyword refers to all level 2 routers, which are interarea routers.

The dlsw, rsrb, and stun keywords refer only to direct encapsulation.

Use Table 5, Table 6, and Table 7 to configure the queueing priorities for your system.


Table 5: Protocol Priority Queue Keywords and Values
Option Description

fragments

Assigns the priority level defined to fragmented IP packets (for use with the IP protocol only). More specifically, this command matches IP packets whose fragment offset field is nonzero. The initial fragment of a fragmented IP packet has a fragment offset of zero, so such packets are not matched by this command.

Note Packets with a nonzero fragment offset do not contain TCP or UDP headers, so other instances of this command that use the tcp or udp keyword will always fail to match such packets.

gt byte-count

Specifies a greater-than count. The priority level assigned goes into effect when a packet size exceeds the value entered for the argument byte-count.

Note The size of the packet must also include additional bytes because of MAC encapsulation on the outgoing interface.

list list-number

Assigns traffic priorities according to a specified list when used with AppleTalk, bridging, IP, IPX, VINES, or XNS. The argument list-number is the access list number as specified by the access-list global configuration command for the specified protocol-name. For example, if the protocol is AppleTalk, list-number should be a valid AppleTalk access list number.

lt byte-count

Specifies a less-than count. The priority level assigned goes into effect when a packet size is less than the value entered for the argument byte-count.

Note The size of the packet must also include additional bytes because of MAC encapsulation on the outgoing interface.

tcp port

Assigns the priority level defined to TCP segments originating from or destined to a specified port (for use with the IP protocol only). Table 6 lists common TCP services and their port numbers.

udp port

Assigns the priority level defined to UDP packets originating from or destined to a specified port (for use with the IP protocol only). Table 7 lists common UDP services and their port numbers.


Table 6: Common TCP Services and Their Port Numbers
Service Port

FTP data

20

FTP

21

SMTP

25

Telnet

23


Table 7: Common UDP Services and Their Port Numbers
Service Port

DNS

53

NFS

2049

RPC

111

SNMP

161

TFTP

69


Note 
Table 6 and Table 7 include some of the more common TCP and UDP port numbers. However, you can specify any port number to be prioritized; you are not limited to those listed.
For some protocols, such as TFTP and FTP, only the initial request uses port 69. Subsequent packets use a randomly chosen port number. For these types of protocols, the use of port numbers fails to be an effective method to manage queued traffic.

Examples

The following example assigns 1 as the arbitrary priority list number, specifies DECnet as the protocol type, and assigns a high-priority level to the DECnet packets transmitted on this interface:

router(config)# priority-list 1 protocol decnet high
 

The following example assigns a medium-priority level to every DECnet packet with a size greater than 200 bytes:

router(config)# priority-list 2 protocol decnet medium gt 200
 

The following example assigns a medium-priority level to every DECnet packet with a size less than 200 bytes:

router(config)# priority-list 4 protocol decnet medium lt 200
 

The following example assigns a high-priority level to traffic that matches IP access list 10:

router(config)# priority-list 1 protocol ip high list 10
 

The following example assigns a medium-priority level to Telnet packets:

router(config)# priority-list 4 protocol ip medium tcp 23
 

The following example assigns a medium-priority level to UDP Domain Name Service packets:

router(config)# priority-list 4 protocol ip medium udp 53
 

The following example assigns a high-priority level to traffic that matches Ethernet type code access list 201:

router(config)# priority-list 1 protocol bridge high list 201
 

The following example assigns a high-priority level to DLSw+ traffic with TCP encapsulation:

router(config)# priority-list 1 protocol ip high tcp 2065
 

The following example assigns a high-priority level to DLSw+ traffic with direct encapsulation:

router(config)# priority-list 1 protocol dlsw high

Note These commands define a rule that determines how packets are attached to an interface. Once the rule is defined, the packet is actually attached to the interface using the priority-group command.

Related Commands

You can use the master indexes or search online to find documentation of related commands.

priority-group
priority-list default
priority-list interface
priority-list queue-limit
show queue
show queueing

priority-list queue-limit

To specify the maximum number of packets that can be waiting in each of the priority queues, use the priority-list queue-limit global configuration command. To select the normal queue, use the no form of this command.

priority-list list-number queue-limit [high-limit [medium-limit [normal-limit [low-limit]]]]
no priority-list list-number queue-limit

Syntax Description

list-number

Any number from 1 to 16 that identifies the priority list.

high-limit
medium-limit
normal-limit
low-limit

(Optional) Priority queue maximum length. A value of 0 for any of the four arguments means that the queue can be of unlimited size for that particular queue.

Default

The default queue limit arguments are listed in Table 8.


Table 8: Default Priority Queue Packet Limits
Priority Queue Argument Packet Limits

high-limit

20

medium-limit

40

normal-limit

60

low-limit

80

Command Mode

Global configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

If a priority queue overflows, excess packets are discarded and quench messages can be sent, if appropriate, for the protocol.

Example

The following example sets the maximum packets in the priority queue to 10:

router(config)# priority-list 2 queue-limit 10 40 60 80

Related Commands

You can use the master indexes or search online to find documentation of related commands.

priority-group
priority-list default
priority-list interface
priority-list protocol
show queue
show queueing

queue-list default

To assign a priority queue for those packets that do not match any other rule in the queue list, use the queue-list default global configuration command. To restore the default value, use the no form of this command.

queue-list list-number default queue-number
no queue-list list-number default queue-number

Syntax Description

list-number

Number of the queue list. Any number from 1 to 16.

queue-number

Number of the queue. Any number from 1 to 16.

Default

The default number of the queue list is queue number 1.

Command Mode

Global configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

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 system assigns the packet to the appropriate queue. The system searches the list in the order it is specified, and the first matching rule terminates the search.

Queue number 0 is a system queue. It is emptied before any of the other queues are processed. The system enqueues high-priority packets, such as keepalives, to this queue.

Use the show interfaces command to display the current status of the output queues.

Example

In the following example, the default queue for list 10 is set to queue number 2:

router(config)# queue-list 10 default 2

Related Commands

You can use the master indexes or search online to find documentation of related commands.

custom-queue-list
queue-list interface
queue-list protocol
queue-list queue byte-count
queue-list queue limit
show queue
show queueing

queue-list interface

To establish queueing priorities on packets entering on an interface, use the queue-list interface global configuration command. To remove an entry from the list, use the no form of the command.

queue-list list-number interface interface-type interface-number queue-number
no queue-list list-number interface interface-type interface-number queue-number

Syntax Description

list-number

Number of the queue list. Any number from 1 to 16.

interface-type

Name of the interface.

interface-number

Number of the interface.

queue-number

Number of the queue. Any number from 1 to 16.

Default

No queueing priorities are established.

Command Mode

Global configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

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 system assigns the packet to the appropriate queue. The list is searched in the order it is specified, and the first matching rule terminates the search.

Example

In the following example, queue list 4 establishes queueing priorities for packets entering on interface tunnel 3. The queue number assigned is 10.

router(config)# queue-list 4 interface tunnel 3 10

Related Commands

You can use the master indexes or search online to find documentation of related commands.

custom-queue-list
queue-list default
queue-list protocol
queue-list queue byte-count
queue-list queue limit
show queue
show queueing

queue-list protocol

To establish queueing priority based upon the protocol type, use the queue-list protocol global configuration command. To remove an entry from the list, use the no form of this command with the appropriate list number.

queue-list list-number protocol protocol-name queue-number queue-keyword keyword-value
no queue-list list-number protocol protocol-name queue-number queue-keyword keyword-value

Syntax Description

list-number

Number of the queue list. Any number from 1 to 16.

protocol-name

Required argument that specifies the protocol type: aarp, apollo, appletalk, arp, bridge (transparent), clns, clns_es, clns_is, cmns, compressedtcp, decnet, decnet_node, decnet_routerl1, decnet_routerl2, dlsw, ip, ipx, pad, rsrb, stun, vines, xns, and x25.

queue-number

Number of the queue. Any number from 1 to 16.

queue-keyword keyword-value

Possible keywords are gt, list, lt, tcp, and udp. See Table 5.

Default

No queueing priorities are established.

Command Mode

Global configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

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.

The decnet_router-l1 keyword refers to the multicast address for all level 1 routers, which are intra-area routers, and the decnet_router-l2 keyword refers to all level 2 routers, which are interarea routers.

The dlsw, rsrb, and stun keywords refer only to direct encapsulation.

Use Table 5, Table 6, and Table 7 from the priority-list protocol command to configure the queueing priorities for your system.

Examples

The following example assigns 1 as the custom queue list, specifies DECnet as the protocol type, and assigns 3 as a queue number to the packets transmitted on this interface:

router(config)# queue-list 1 protocol decnet 3
 

The following example assigns DECnet packets with a size greater than 200 bytes to queue number  2:

router(config)# queue-list 2 protocol decnet 2 gt 200
 

The following example assigns DECnet packets with a size less than 200 bytes to queue number 2:

router(config)# queue-list 4 protocol decnet 2 lt 200
 

The following example assigns traffic that matches IP access list 10 to queue number 1:

router(config)# queue-list 1 protocol ip 1 list 10
 

The following example assigns Telnet packets to queue number 2:

router(config)# queue-list 4 protocol ip 2 tcp 23
 

The following example assigns UDP Domain Name Service packets to queue number 2:

router(config)# queue-list 4 protocol ip 2 udp 53
 

The following example assigns traffic that matches Ethernet type code access list 201 to queue number 1:

router(config)# queue-list 1 protocol bridge 1 list 201

Related Commands

You can use the master indexes or search online to find documentation of related commands.

custom-queue-list
queue-list default
queue-list queue byte-count
queue-list queue limit
show queue
show queueing

queue-list queue byte-count

To specify how many bytes the system allows to be delivered from a given queue during a particular cycle, use the queue-list queue byte-count global configuration command. To return the byte count to the default value, use the no form of the command.

queue-list list-number queue queue-number byte-count byte-count-number
no queue-list list-number queue queue-number byte-count byte-count-number

Syntax Description

list-number

Number of the queue list. Any number from 1 to 16.

queue-number

Number of the queue. Any number from 1 to 16.

byte-count-number

The lower boundary on how many bytes the system allows to be delivered from a given queue during a particular cycle.

Default

The default byte count is 1500 bytes.

Command Mode

Global configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

Example

In the following example, queue list 9 establishes the byte count as 1400 for queue number 10:

router(config)# queue-list 9 queue 10 byte-count 1400

Related Commands

You can use the master indexes or search online to find documentation of related commands.

custom-queue-list
queue-list default
queue-list interface
queue-list protocol
queue-list queue byte-count
queue-list queue limit
show queue
show queueing

queue-list queue limit

To designate the queue length limit for a queue, use the queue-list queue limit global configuration command. To return the queue length to the default value, use the no form of the command.

queue-list list-number queue queue-number limit limit-number
no queue-list list-number queue queue-number limit limit-numberr

Syntax Description

list-number

Number of the queue list. Any number from 1 to 16.

queue-number

Number of the queue. Any number from 1 to 16.

limit-number

Maximum number of packets that can be enqueued at any time. The range is 0 to 32767 queue entries. A value of 0 means that the queue can be of unlimited size.

Default

The default queue is 20 entries.

Command Mode

Global configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

Example

In the following example, the queue length of queue 10 is increased to 40:

router(config)# queue-list 5 queue 10 limit 40

Related Commands

You can use the master indexes or search online to find documentation of related commands.

custom-queue-list
queue-list default
queue-list interface
queue-list protocol
queue-list queue byte-count
show queue
show queueing


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