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Table Of Contents
Tag Switching/MPLS Terminology
Supporting CoS in an MPLS Backbone
LSRs Used at the Edge of an MPLS Network
LSRs Used at the Core of an MPLS Network
Interfaces Supporting MPLS CoS Features
Benefits of MPLS CoS in IP Backbones
Related Features and Technologies
Supported Standards, MIBs, and RFCs
Configuring MPLS CoS on Cisco 7200/7500 Series Routers
Configuring WRED/DWRED on Cisco 7200/7500 Series Routers
Verifying WRED/DWRED on Cisco 7200/7500 Series Routers
Configuring CAR/DCAR on Cisco 7200/7500 Series Routers
Verifying CAR/DCAR Configuration on Cisco 7200/7500 Series Routers
Configuring CBWFQ on Cisco 7200/7500 Series Routers
Verifying CBWFQ Configuration on Cisco 7200/7500 Series Routers
Configuring MPLS CoS on a Cisco 12000 Series GSR Router
Configuring WRED/MDRR on a Cisco 12000 Series GSR Router
Configuring Outgoing GSR Interfaces in the Transmit (frfab) Direction
Verifying WRED/MDRR in the Transmit (frfab) Direction
Configuring Incoming GSR Interfaces in the Receive (tofab) Direction
Verifying WRED/MDRR in the Receive (tofab) Direction
Configuration Examples for Cisco 7200/7500 Series Routers
Configuring Cisco Express Forwarding
Configuration Examples for Cisco 12000 Series GSR Routers
Configuring WRED on a POS Interface
Configuring MDRR on a POS Interface
WRED/MDRR Configuration Example
MPLS Quality of Service (QoS)
Feature History
Note
MPLS Class of Service is now referred to as MPLS Quality of Service. This transition reflects the growth of MPLS to encompass a wider meaning and highlight the path towards future enhancements.
This feature module describes the use of the MPLS class of service (CoS) functionality in an MPLS network. The document contains the following major sections:
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Feature Overview
MPLS CoS functionality enables network administrators to provide differentiated services across an MPLS network. Network administrators can satisfy a wide range of networking requirements by specifying the class of service applicable to each transmitted IP packet. Different classes of service can be established for IP packets by setting the IP precedence bit in the header of each packet.
MPLS CoS supports the following differentiated services in an MPLS network:
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Table 1 describes the MPLS CoS services and functions.
For more information about configuring CoS functions (CAR, WRED, and WFQ), see the Cisco IOS Quality of Service Solutions Configuration Guide.
For complete command syntax information for CAR, WRED, and WFQ, see the Cisco IOS Quality of Service Solutions Command Reference.
MPLS CoS enables you to duplicate Cisco IOS IP CoS (Layer 3) features as closely as possible in MPLS devices, including label edge switch routers (edge LSRs) and label switch routers (LSRs). MPLS CoS functions map nearly one-for-one to IP CoS functions on all types of interfaces.
Tag Switching/MPLS Terminology
Table 2 lists the existing legacy tag switching terms and the new, equivalent MPLS IETF terms used in this document and other related Cisco publications.
Supporting CoS in an MPLS Backbone
This section describes the following types of MPLS CoS configurations:
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LSRs Used at the Edge of an MPLS Network
LSRs used at the edge of an MPLS network backbone are usually Cisco 7200 or Cisco 7500 series routers running MPLS software. The edge LSRs can be at the ingress or the egress of the network.
At the ingress of an MPLS network, routers process packets as follows:
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In either case, LSRs enforce the defined differentiation by continuing to employ WRED or CBWFQ on every ingress router.
At the egress of an MPLS network, routers process packets as follows:
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LSRs Used at the Core of an MPLS Network
LSRs used at the core of an MPLS network are usually Cisco GSR 12000 series routers or Cisco 7500 series routers running MPLS software. These routers at the core of an MPLS network process packets as follows:
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Interfaces Supporting MPLS CoS Features
This section identifies the MPLS CoS features that are supported on various Cisco devices and interfaces.
Table 3 lists the MPLS CoS features that are supported on packet interfaces.
1. This feature is supported in IOS release 12.1 and IOS release 12.1T
Table 4 lists the MPLS CoS features that are supported on ATM interfaces.
1. This feature is available on the ATM Lite port adapter (PA-A1).
2. This feature is available on the ATM Deluxe port adapter (PA-A3).
Benefits of MPLS CoS in IP Backbones
You realize the following benefits when you use MPLS CoS in a backbone consisting of IP routers running MPLS:
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Related Features and Technologies
You can use MPLS CoS functionality in any MPLS network.
Related Documents
For additional information about MPLS Quality of Service, see the following documents:
Cisco IOS Quality of Service Solutions Configuration Guide, Release 12.2
Cisco IOS Quality of Service Solutions Command Reference, Release 12.2
Supported Platforms
The routers that support MPLS CoS at the edge and core of a packet-based MPLS network are listed below:
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Determining Platform Support Through Cisco Feature Navigator
Cisco IOS software is packaged in feature sets that are supported on specific platforms. To get updated information regarding platform support for this feature, access Cisco Feature Navigator. Cisco Feature Navigator dynamically updates the list of supported platforms as new platform support is added for the feature.
Cisco Feature Navigator is a web-based tool that enables you to quickly determine which Cisco IOS software images support a specific set of features and which features are supported in a specific Cisco IOS image. You can search by feature or release. Under the release section, you can compare releases side by side to display both the features unique to each software release and the features in common.
To access Cisco Feature Navigator, you must have an account on Cisco.com. If you have forgotten or lost your account information, send a blank e-mail to cco-locksmith@cisco.com. An automatic check will verify that your e-mail address is registered with Cisco.com. If the check is successful, account details with a new random password will be e-mailed to you. Qualified users can establish an account on Cisco.com by following the directions found at this URL:
Cisco Feature Navigator is updated regularly when major Cisco IOS software releases and technology releases occur. For the most current information, go to the Cisco Feature Navigator home page at the following URL:
Availability of Cisco IOS Software Images
Platform support for particular Cisco IOS software releases is dependent on the availability of the software images for those platforms. Software images for some platforms may be deferred, delayed, or changed without prior notice. For updated information about platform support and availability of software images for each Cisco IOS software release, refer to the online release notes or, if supported, Cisco Feature Navigator.
Supported Standards, MIBs, and RFCs
Standards
No new or modified standards are supported by this MPLS CoS feature.
MIBs
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To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL:
http://tools.cisco.com/ITDIT/MIBS/servlet/index
If Cisco MIB Locator does not support the MIB information that you need, you can also obtain a list of supported MIBs and download MIBs from the Cisco MIBs page at the following URL:
http://www.cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml
To access Cisco MIB Locator, you must have an account on Cisco.com. If you have forgotten or lost your account information, send a blank e-mail to cco-locksmith@cisco.com. An automatic check will verify that your e-mail address is registered with Cisco.com. If the check is successful, account details with a new random password will be e-mailed to you. Qualified users can establish an account on Cisco.com by following the directions found at this URL:
RFCs
No new or modified RFCs are supported by this MPLS CoS feature.
Prerequisites
To use MPLS CoS to full advantage in your network, the following functionality must be supported:
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WFQ applies priorities, or weights, to traffic to classify the traffic into flows and determine how much bandwidth to allow each flow. WFQ moves interactive traffic to the front of a queue to reduce response time and fairly shares the remaining bandwidth among high-bandwidth flows.
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IP precedence bits, contained in the type of service (ToS) octet in the IP packet header, are used to denote the relative importance or priority of an IP packet. WRED uses these IP precedence values to classify packets into different discard priorities or classes of service.
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In MDRR, IP traffic is mapped to different classes of service queues. A group of queues is assigned to each traffic destination. On the transmit side of the platform, a group of queues is defined on a per-interface basis; on the receive side of the platform, a group of queues is defined on a per-destination basis. IP packets are then mapped to these queues, based on their IP precedence value.
These queues are serviced on a round-robin basis, except for a queue that has been defined to run in either of two ways: a) strict priority mode, or b) alternate priority mode.
In strict priority mode, the high priority queue is serviced whenever it is not empty; this ensures the lowest possible delay for high priority traffic. In this mode, however, the possibility exists that other traffic might not be serviced for long periods of time if the high priority queue is consuming most of the available bandwidth.
In alternate priority mode, the traffic queues are serviced in turn, alternating between the high priority queue and the remaining queues.
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Configuration Tasks
This section describes the following configuration tasks:
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Configuring MPLS CoS on Cisco 7200/7500 Series Routers
Configuring WRED/DWRED on Cisco 7200/7500 Series Routers
To configure weighted random early detection (WRED) or distributed weighted random early detection (DWRED) on a Cisco 7200 or 7500 series router interface, issue the commands shown in the following table.
Verifying WRED/DWRED on Cisco 7200/7500 Series Routers
To verify weighted random early detection (WRED) or distributed weighted random early detection (DWRED) on a Cisco 7200 or 7500 series router interface, issue a command of the form shown in the following table. This example is based on "Router2" in the network topology shown in Figure 1.
Configuring CAR/DCAR on Cisco 7200/7500 Series Routers
To configure committed access rate (CAR) or distributed committed access rate (DCAR) on a Cisco 7200 or 7500 series router interface, issue the commands shown in the following table.
Verifying CAR/DCAR Configuration on Cisco 7200/7500 Series Routers
To verify CAR/DCAR configuration on a Cisco 7200 or 7500 series router interface, issue a command of the following form. This example is based on "Router 2" in the network topology shown in Figure 1.
Router2# show interfaces e1/3 rate-limitEthernet1/3Inputmatches:access-group 101params: 496000 bps, 32000 limit, 64000 extended limitconformed 2137 packets, 576990 bytes; action:set-prec-transmit 4exceeded 363 packets, 98010 bytes; action:set-prec-transmit 0last packet:11788ms ago, current burst:39056 byteslast cleared 00:01:18 ago, conformed 58000 bps, exceeded 10000 bpsConfiguring CBWFQ on Cisco 7200/7500 Series Routers
To configure class-based weighted fair queueing (CBWFQ) on a Cisco 7200 or 7500 series router interface, issue the commands shown in the following table.
Verifying CBWFQ Configuration on Cisco 7200/7500 Series Routers
To verify CBWFQ configuration on a Cisco 7200 or 7500 series router interface, issue a command of the following form. This example is based on "Router 5" in the network topology shown in Figure 1.
Router5# show policy-map interface fa5/1/0FastEthernet5/1/0service-policy output:outputmapclass-map:prec_01 (match-all)522 packets, 322836 bytes5 minute rate 1000 bpsmatch:ip precedence 0 1queue size 0, queue limit 1356packet output 522, packet drop 0tail/random drop 0, no buffer drop 0, other drop 0bandwidth:class-based wfq, weight 10random-detect:Exp-weight-constant:9 (1/512)Mean queue depth:0Class Random Tail Minimum Maximum Mark Outputdrop drop threshold threshold probability packets0 0 0 3390 6780 1/10 5221 0 0 3813 6780 1/10 02 0 0 4236 6780 1/10 03 0 0 4659 6780 1/10 04 0 0 5082 6780 1/10 05 0 0 5505 6780 1/10 06 0 0 5928 6780 1/10 07 0 0 6351 6780 1/10 0class-map:prec_23 (match-all)0 packets, 0 bytes5 minute rate 0 bpsmatch:ip precedence 2 3queue size 0, queue limit 0packet output 0, packet drop 0tail/random drop 0, no buffer drop 0, other drop 0bandwidth:class-based wfq, weight 15random-detect:Exp-weight-constant:9 (1/512)Mean queue depth:0Class Random Tail Minimum Maximum Mark Outputdrop drop threshold threshold probability packets0 0 0 0 0 1/10 01 0 0 0 0 1/10 02 0 0 0 0 1/10 03 0 0 0 0 1/10 04 0 0 0 0 1/10 05 0 0 0 0 1/10 06 0 0 0 0 1/10 07 0 0 0 0 1/10 0class-map:prec_45 (match-all)2137 packets, 576990 bytes5 minute rate 16000 bpsmatch:ip precedence 4 5queue size 0, queue limit 2712packet output 2137, packet drop 0tail/random drop 0, no buffer drop 0, other drop 0bandwidth:class-based wfq, weight 20random-detect:Exp-weight-constant:9 (1/512)Mean queue depth:0Class Random Tail Minimum Maximum Mark Outputdrop drop threshold threshold probability packets0 0 0 3390 6780 1/10 01 0 0 3813 6780 1/10 02 0 0 4236 6780 1/10 03 0 0 4659 6780 1/10 04 0 0 5082 6780 1/10 21375 0 0 5505 6780 1/10 06 0 0 5928 6780 1/10 07 0 0 6351 6780 1/10 0class-map:prec_67 (match-all)0 packets, 0 bytes5 minute rate 0 bpsmatch:ip precedence 6 7queue size 0, queue limit 0packet output 0, packet drop 0tail/random drop 0, no buffer drop 0, other drop 0bandwidth:class-based wfq, weight 25random-detect:Exp-weight-constant:9 (1/512)Mean queue depth:0Class Random Tail Minimum Maximum Mark Outputdrop drop threshold threshold probability packets0 0 0 0 0 1/10 01 0 0 0 0 1/10 02 0 0 0 0 1/10 03 0 0 0 0 1/10 04 0 0 0 0 1/10 05 0 0 0 0 1/10 06 0 0 0 0 1/10 07 0 0 0 0 1/10 0class-map:class-default (match-any)0 packets, 0 bytes5 minute rate 0 bpsmatch:any0 packets, 0 bytes5 minute rate 0 bpsqueue size 0, queue limit 4068packet output 90, packet drop 0tail/random drop 0, no buffer drop 0, other drop 0Router5#Router5# show queueing interface fa5/1/0Interface FastEthernet5/1/0 queueing strategy:VIP-based fair queueingFastEthernet5/1/0 queue size 0pkts output 2756, wfq drops 0, nobuffer drops 0WFQ:aggregate queue limit 13561 max available buffers 13561Class 0:weight 30 limit 4068 qsize 0 pkts output 97 drops 0Class 2:weight 10 limit 1356 qsize 0 pkts output 522 drops 0Class 3:weight 15 limit 0 qsize 0 pkts output 0 drops 0Class 4:weight 20 limit 2712 qsize 0 pkts output 2137 drops 0Class 5:weight 25 limit 0 qsize 0 pkts output 0 drops 0Configuring MPLS CoS on a Cisco 12000 Series GSR Router
Configuring WRED/MDRR on a Cisco 12000 Series GSR Router
To configure WRED/MDRR on a Cisco 12000 series GSR router interface, issue the commands shown in the following table.
Creates a cos-queue-group. For an example of a complete cos-queue-group, see Step 1 in the table under the heading entitled "Configuring Outgoing GSR Interfaces in the Transmit (frfab) Direction."
Step 2
Router(config)# interface type numberSpecifies the interface type and number.
Step 3
Assigns a cos-queue-group to the transmit interface.
Configuring Outgoing GSR Interfaces in the Transmit (frfab) Direction
To configure MPLS CoS on a Cisco 12000 series GSR router interface in the transmit direction, issue the commands shown in the following table.
Verifying WRED/MDRR in the Transmit (frfab) Direction
To verify WRED/MDRR configuration in the transmit direction on a Cisco 12000 series GSR router interface, issue a command of the following form.
Router# show interface pos6/0:1 random-detectPOS6/0:1cos-queue-group: wred-testRED Drop CountsTx Link To FabricRED Label Random Threshold Random Threshold0 0 0 0 01 0 0 0 02 0 0 0 03 72913 345267 0 04 0 0 0 05 216225 433182 0 06 0 0 0 0Tx-queue-limit drops: 0Queue LengthsTx Queue (DRR configured) wred-testQueue Average High Water Mark Weight0 0.000 0.000 101 0.000 0.000 102 0.000 0.000 103 846.000 956.000 104 0.000 0.000 105 873.000 1141.000 106 0.000 0.000 10Low latency 0.000 0.000 10Tx RED configPrecedence 0: not configured for dropPrecedence 1: not configured for dropPrecedence 2: not configured for dropPrecedence 3: 500 min threshold, 1000 max threshold, 1/1 mark weightPrecedence 4: not configured for dropPrecedence 5: 700 min threshold, 1200 max threshold, 1/1 mark weightPrecedence 6: not configured for dropPrecedence 7: not configured for dropweight 1/2Configuring Incoming GSR Interfaces in the Receive (tofab) Direction
To configure MPLS CoS on a Cisco 12000 series GSR router interface in the receive direction, issue the commands shown in the following table.
Verifying WRED/MDRR in the Receive (tofab) Direction
To verify the configuration of WRED/MDRR in the receive direction of an interface on a Cisco 12000 series GSR router interface, issue a command of the following form.
Router# show cos statistics (Supported on Engine 0 only)Slot 4---------------Dest slot 6cos-queue-group: wred-testRED Drop CountsTo FabricRED Label Random Threshold0 534885 2507931 538361 2488462 526379 2594003 520537 2555984 0 05 0 06 0 0Queue LengthsTo Fabric Queues (DRR configured) wred-testQueue Average High Water Mark Weight0 712.000 5562.000 101 702.000 7716.000 102 702.000 11540.000 103 753.000 14368.000 104 0.000 0.000 105 0.000 0.000 106 0.000 0.000 10Low latency 0.000 0.000 10Tx RED configPrecedence 0: 500 min threshold, 1000 max threshold, 1/1 mark weightPrecedence 1: 500 min threshold, 1000 max threshold, 1/1 mark weightPrecedence 2: 500 min threshold, 1000 max threshold, 1/1 mark weightPrecedence 3: 500 min threshold, 1000 max threshold, 1/1 mark weightPrecedence 4: not configured for dropPrecedence 5: not configured for dropPrecedence 6: not configured for dropPrecedence 7: not configured for dropweight 1/2Slot 5---------------Dest slot 6cos-queue-group: wred-testRED Drop CountsTo FabricRED Label Random Threshold0 554626 2496511 543842 2631472 538321 2669743 534728 2581484 0 05 0 06 0 0Queue LengthsTo Fabric Queues (DRR configured) wred-testQueue Average High Water Mark Weight0 753.000 6539.000 101 761.000 10190.000 102 753.000 11272.000 103 771.000 5980.000 104 0.000 0.000 105 0.000 0.000 106 0.000 0.000 10Low latency 0.000 0.000 10Tx RED configPrecedence 0: 500 min threshold, 1000 max threshold, 1/1 mark weightPrecedence 1: 500 min threshold, 1000 max threshold, 1/1 mark weightPrecedence 2: 500 min threshold, 1000 max threshold, 1/1 mark weightPrecedence 3: 500 min threshold, 1000 max threshold, 1/1 mark weightPrecedence 4: not configured for dropPrecedence 5: not configured for dropPrecedence 6: not configured for dropPrecedence 7: not configured for dropweight 1/2Configuration Examples for Cisco 7200/7500 Series Routers
This section provides the following configuration examples for interfaces on Cisco 7200 and Cisco 7500 series routers.
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The configuration examples in this section are based on the sample network topology shown in Figure 1.
A later section entitled "Configuration Examples for Cisco 12000 Series GSR Routers" provides configuration examples for packet interfaces on Cisco 12000 series GSR routers. These configuration examples are likewise based on the sample network topology shown in Figure 1.
Figure 1 Sample Network Topology for Configuring MPLS CoS on Router Interfaces
Configuring Cisco Express Forwarding
Cisco express forwarding (CEF) is a prerequisite for using MPLS CoS; CEF must be running on all routers and switches in the MPLS network. To enable CEF on a router or a switch, issue the following command, as appropriate:
ip cef distributed (for Cisco 7500 series routers)!ip cef (for Cisco 7200 series routers)!Running IP on Router 1
The following commands enable IP routing on Router 1 (see Figure 1). All routers in Figure 1 must have IP enabled.
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!ip routing!hostname R1!interface Loopback0ip address 11.11.11.11 255.255.255.255!interface Ethernet0/3ip address 90.0.0.1 255.0.0.0!router ospf 100network 11.0.0.0 0.255.255.255 area 100network 90.0.0.0 0.255.255.255 area 100Running MPLS on Router 2
Router 2 (see Figure 1) is a label edge router. CEF and MPLS must be enabled on this router. CAR is also configured on Router 2 and interface e1/3. The CAR policy used at interface e1/3 acts on incoming traffic matching access-list 101. If the traffic rate is less than the committed information rate (in this example, 496000), the traffic will be sent with IP precedence 4. Otherwise, this traffic will be sent with IP precedence 0.
!ip routing!hostname R2!ip cefmpls iptag-switching advertise-tags!interface Loopback0ip address 10.10.10.10 255.255.255.255!interface Ethernet1/3ip address 90.0.0.2 255.0.0.0rate-limit input access-group 101 496000 32000 64000 conform-action set-prec-transmit 4 exceed-action set-prec-transmit 0!interface POS6/0ip address 91.0.0.1 255.0.0.0mpls label protocol ldpmpls iprandom-detectclock source internal!router ospf 100network 10.0.0.0 0.255.255.255 area 100network 90.0.0.0 0.255.255.255 area 100network 91.0.0.0 0.255.255.255 area 100!access-list 101 permit ip host 11.11.11.11 anyRunning MPLS on Router 3
Router 3 (see Figure 1) is running MPLS. CEF and MPLS must be enabled on this router.
!ip routingmpls iptag-switching advertise-tags!hostname R3!interface Loopback0ip address 15.15.15.15 255.255.255.255!interface POS0/1ip address 91.0.0.2 255.0.0.0mpls label protocol ldpmpls ipcrc 16!interface POS3/0ip address 92.0.0.1 255.0.0.0mpls label protocol ldpmpls ipcrc 16clock source internaltx-cos stm16-rx!router ospf 100network 15.0.0.0 0.255.255.255 area 100network 91.0.0.0 0.255.255.255 area 100network 92.0.0.0 0.255.255.255 area 100!cos-queue-group stm16-rxprecedence 0 random-detect-label 0precedence 0 queue 0precedence 1 queue 1precedence 1 random-detect-label 1precedence 2 queue 2precedence 2 random-detect-label 2precedence 3 random-detect-label 2precedence 4 random-detect-label 2precedence 5 random-detect-label 2precedence 6 random-detect-label 2precedence 7 queue low-latencyprecedence 7 random-detect-label 2random-detect-label 0 250 1000 1random-detect-label 1 500 1250 1random-detect-label 2 750 1500 1queue 0 50queue 1 100queue 2 150queue low-latency alternate-priority 500Running MPLS on Router 4
Router 4 (see Figure 1) is running MPLS. CEF and MPLS must be enabled on this router.
!ip routingmpls iptag-switching advertise-tags!hostname R4!interface Loopback0ip address 13.13.13.13 255.255.255.255!interface POS1/2ip address 93.0.0.1 255.0.0.0mpls label protocol ldpmpls ipcrc 16clock source internaltx-cos stm16-rx!router ospf 100network 13.0.0.0 0.255.255.255 area 100network 92.0.0.0 0.255.255.255 area 100network 93.0.0.0 0.255.255.255 area 100!cos-queue-group stm16-rxprecedence 0 queue 0precedence 0 random-detect-label 0precedence 1 queue 1precedence 1 random-detect-label 1precedence 2 queue 2precedence 2 random-detect-label 2precedence 3 random-detect-label 2precedence 4 random-detect-label 2precedence 5 random-detect-label 2precedence 6 random-detect-label 2precedence 7 queue low-latencyrandom-detect-label 0 250 1000 1random-detect-label 1 500 1250 1random-detect-label 2 750 1500 1queue 0 50queue 1 100queue 2 150queue low-latency alternate-priority 200Running MPLS on Router 5
Router 5 (see Figure 1) is running MPLS. CEF and MPLS must be enabled on this router. Router 5 has CBWFQ enabled on interface fa5/1/0. In this example, class-maps are created, matching packets with various IP precedence values. These class-maps are then used in a policy-map named "outputmap," where CBWFQ is assigned to each class. Finally, the policy-map is assigned to the outbound interface fa5/1/0.
!ip routingmpls iptag-switching advertise-tags!hostname R5!!class-map match-all prec_01match ip precedence 0 1class-map match-all prec_23match ip precedence 2 3class-map match-all prec_45match ip precedence 4 5class-map match-all prec_67match ip precedence 6 7!!policy-map outputmapclass prec_01bandwidth 10000random-detectclass prec_23bandwidth 15000random-detectclass prec_45bandwidth 20000random-detectclass prec_67bandwidth 25000random-detect!ip cef distributed!interface Loopback0ip address 12.12.12.12 255.255.255.255no ip directed-broadcast!interface POS1/1/0ip address 93.0.0.2 255.0.0.0ip route-cache distributedmpls label protocol ldpmpls ip!interface FastEthernet5/1/0ip address 94.0.0.1 255.0.0.0ip route-cache distributedfull-duplexservice-policy output outputmap!router ospf 100network 12.0.0.0 0.255.255.255 area 100network 93.0.0.0 0.255.255.255 area 100network 94.0.0.0 0.255.255.255 area 100Running IP on Router 6
Router 6 (see Figure 1) is running IP. CEF must be enabled on this router.
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!ip routing!hostname R6!ip cef distributed!interface Loopback0ip address 14.14.14.14 255.255.255.255!interface FastEthernet2/0/0ip address 94.0.0.2 255.0.0.0ip route-cache distributedfull-duplex!router ospf 100network 14.0.0.0 0.255.255.255 area 100network 94.0.0.0 0.255.255.255 area 100!Configuration Examples for Cisco 12000 Series GSR Routers
This section provides the following configuration examples for packet interfaces on Cisco 12000 series GSR routers.
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These configuration examples are based on the sample MPLS network topology shown in Figure 1.
Configuring WRED on a POS Interface
To configure WRED on a POS interface, perform the following steps:
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Router(config)# cos-queue-group stm16-rx(where stm16-rx is the cos-queue group to apply)Router(config-cos-que)# random-detect-label 0 250 1000 1Router(config-cos-que)# random-detect-label 1 500 1250 1Router(config-cos-que)# random-detect-label 2 750 1500 1Router(config-cos-que)# precedence 0 random-detect-label 0Router(config-cos-que)# precedence 1 random-detect-label 1Router(config-cos-que)# precedence 2 random-detect-label 2 Maps precedenceRouter(config-cos-que)# precedence 3 random-detect-label 2 values to the set ofRouter(config-cos-que)# precedence 4 random-detect-label 2 WRED parametersRouter(config-cos-que)# precedence 5 random-detect-label 2 to use.Router(config-cos-que)# precedence 6 random-detect-label 2Router(config-cos-que)# precedence 7 random-detect-label 2Router(config-cos-que)# exponential-weighting-constant 9 Determines how closely weightedaverage will follow instantaneousqueue depth.2.
For the transmit (TX) direction, apply WRED parameters on the interface:
Router(config-if)# tx-cos stm16-txFor the receive (RX) direction:
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Router(config)# slot-table-cos stm16-rx-tablewhere stm16-rx-table is the label of the created table.
Router(config-slot-cos)# destination-slot all stm16-rxRouter (config-slot-cos)# exitb.
Router(config)# rx-cos-slot 1 stm16-rx-tablewhere 1 is the receive (RX) line on which WRED is enabled.
Configuring MDRR on a POS Interface
To configure MDRR on a POS interface, create an MDRR cos-queue-group, as shown in the following example:
Router(config)# cos-queue-group stm16-rxRouter(config-cos-que)# precedence 0 queue 0Router(config-cos-que)# precedence 1 queue 1 (Maps IP precedences to MDRR queues)Router(config-cos-que)# precedence 2 queue 2Router(config-cos-que)# precedence 7 queue low-latency (Maps precedence 7 to low latency queue)Router(config-cos-que)# queue 0 50 (Queue 0 has weight value of 50)Router(config-cos-que)# queue 1 100 (Queue 1 has weight value of 100)Router(config-cos-que)# queue 2 150 (Queue 2 has weight value of 150)Router(config-cos-que)# queue low-latency alternate-priority 200(low-latency queue works in alternate-priority mode)Router(config-cos-que)# exitRouter(config)#WRED/MDRR Configuration Example
cos-queue-group stm16-rxrandom-detect-label 0 250 1000 1random-detect-label 1 500 1250 1random-detect-label 2 750 1500 1precedence 0 random-detect-label 0precedence 1 random-detect-label 1precedence 2 random-detect-label 2precedence 3 random-detect-label 2precedence 4 random-detect-label 2precedence 5 random-detect-label 2precedence 6 random-detect-label 2exponential-weighting-constant 9precedence 0 queue 0precedence 1 queue 1precedence 2 queue 2precedence 3 queue 1precedence 4 queue 1precedence 5 queue 1precedence 6 queue 2precedence 7 queue low-latencyqueue 0 50queue 1 100queue 2 150queue low-latency alternate-priority 200exitGlossary
ATM edge LSR—A router that is connected to the ATM-LSR cloud through LC-ATM interfaces. The ATM edge LSR adds labels to unlabeled packets and strips labels from labeled packets.
ATM-LSR—A label switch router with a number of LC-ATM interfaces. The router forwards the cells among these interfaces using labels carried in the VPI/VCI field.
CAR—Committed access rate (packet classification). CAR is the main feature supporting packet classification. CAR uses the type of service (ToS) bits in the IP header to classify packets. You can use the CAR classification commands to classify or reclassify a packet.
CoS—Class of service. A feature that provides scalable, differentiated types of service across an MPLS network.
IP precedence—A 3-bit value in a ToS byte used for assigning precedence to IP packets.
label—A short, fixed-length construct that tells switching nodes how to forward data (packets or cells).
label-controlled ATM interface (LC-ATM interface)—An interface on a router or switch that uses label distribution procedures to negotiate label VCs.
label imposition—The process of putting the first label on a packet.
label switch—A node that forwards units of data (packets or cells) on the basis of labels.
label-switched path (LSP)—An LSP results from a sequence of hops (Router 0...Router n) through which a packet travels from R0 to Rn by means of label switching mechanisms. A label-switched path can be determined dynamically (based on normal routing mechanisms), or it can be defined explicitly.
label-switched path (LSP) tunnel—A configured connection between two routers, in which label switching techniques are used for packet forwarding.
label switching router (LSR)—A Layer 3 router that forwards a packet based on the value of a label encapsulated in the packet.
label VC (LVC)—An ATM virtual circuit that is set up through ATM LSR label distribution procedures.
LBR—Label bit rate. A service category defined by this document for label-VC traffic. Link and per-VC bandwidth sharing can be controlled by relative bandwidth configuration at the edge and each switch along a label-VC. No ATM traffic-related parameters are specified.
LDP—Label Distribution Protocol. The protocol used to distribute label bindings to LSRs.
LFIB—Label forwarding information base. The data structure used by switching functions to switch labeled packets.
LIB—Label information base. A database used by an LSR to store labels learned from other LSRs, as well as labels assigned by the local LSR.
MPLS—Multiprotocol label switching. An emerging industry standard that defines support for MPLS forwarding of packets along normally routed paths (sometimes called MPLS hop-by-hop forwarding).
RED—Random early detection. A congestion avoidance algorithm in which a small percentage of packets are dropped when congestion is detected and before the queue in question overflows completely.
ToS bits—Type of service bits. A byte in the IPv4 header.
traffic engineering—The techniques and processes used to cause routed traffic to travel through the network on a path other than the one that would have been chosen if standard routing methods had been applied.
traffic engineering tunnel—A label-switched tunnel that is used for traffic engineering. Such a tunnel is set up through means other than normal Layer 3 routing; it is used to direct traffic over a path different from the one that Layer 3 routing would cause the tunnel to take.
VPN—Virtual private network. Enables IP traffic to use tunneling to transport data securely over a public TCP/IP network.
WRED—Weighted random early detection. A variant of RED in which the probability of a packet being dropped depends on either its IP precedence, CAR marking, or MPLS CoS (as well as other factors in the RED algorithm).
WFQ—Weighted fair queueing. A queue management algorithm that provides a certain fraction of link bandwidth to each of several queues, based on a relative bandwidth applied to each of the queues.
