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Table Of Contents
MPLS QoS Multi-VC Mode for PA-A3
Tag Switching/MPLS Terminology
MPLS QoS Support in an MPLS Network
LSRs Used at the Edge of an MPLS Network
LSRs Used in the Core of an MPLS Network
ATM-LSRs Used in the Core of an MPLS Network
ATM Switches Used Without MPLS Enabled
Using MPLS QoS in ATM Backbone
Related Features and Technologies
Supported Standards, MIBs, and RFCs
Configuring Cisco Express Forwarding
Optionally Setting the MPLS Experimental Field Value
Using Modular QoS CLI to Configure Ingress Label Switching Router
Using CAR to Configure Ingress Label Switching Router
Configuring Class of Service for IP Packets on Output
Configuring MPLS QoS in Core of ATM Network
Configuring Multi-VC Mode in MPLS-Enabled Network
Configuring Multi-VCs Using the QoS-Map Function
Configuring Queueing Functions on Router Output Interfaces
Configuring CBWFQ on Cisco 7200/7500 Series and Cisco MGX RPM-PR Router Interfaces
Configuring WRED on Cisco 7200/7500 Series or Cisco MGX RPM-PR Router Interfaces
Setting the ATM-CLP Bit on PA-A3 Interfaces
Verifying QoS Configuration on ATM Interfaces
Running IP on Customer Edge Router 1 (CE1)
Running IP on Customer Edge Router 2 (CE2)
Running MPLS on Provider Edge Router 1 (PE1)
Running MPLS on Provider Edge Router 2 (PE2)
MPLS QoS Multi-VC Mode for PA-A3
Feature History
This document describes the MPLS QoS Multi-VC Mode for PA-A3 feature being made available to customers for use with Cisco IOS Release 12.2(4)T. This document contains the following sections:
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Supported Standards, MIBs, and RFCs
Feature Overview
MPLS quality of service (QoS) functionality enables network administrators to satisfy a wide range of requirements in transmitting IP packets through an MPLS-enabled network. Table 1 contains a brief summary of three primary MPLS QoS service offerings made available to customers through earlier Cisco IOS releases.
For more information about configuring the MPLS QoS services summarized in Table 1, see the Cisco IOS Quality of Service Solutions Configuration Guide.
For complete command syntax information for configuring CAR, WRED, and CBWFQ functionality, see the Cisco IOS Quality of Service Solutions Command Reference.
In general, MPLS QoS enables the duplication of Cisco IOS IP QoS (Layer 3) functions on MPLS devices, including label edge routers (LERs), label switching routers (LSRs), and Asynchronous Transfer Mode LSRs (ATM-LSRs). MPLS QoS functions map nearly one-for-one to IP QoS functions on all types of interfaces.
The MPLS QoS Multi-VC Mode functionality described in this document significantly enhances the generalized MPLS QoS capabilities outlined in Table 1. Specifically, this new MPLS QoS feature enables users to map the experimental (EXP) field value of an MPLS label to an ATM virtual circuit (VC) to create sets of labeled virtual circuits (LVCs). Each set consists of multiple LVCs, and each LVC is treated as a member of the set.
All members of a set are associated with a label-switched path (LSP) that is set up between a pair of ATM-connected routers in the user's networking environment, and each member of a set has a different quality of service (QoS) from other members of the set.
By means of multi-VC sets, differentiated services can be provided to users of MPLS-enabled service provider networks. This service differentiation is accomplished by setting an appropriate value in the experimental (EXP) field in the header of each incoming packet as it is received by the provider edge (PE) router in the service provider network. This process is discussed in greater detail in the "Optionally Setting the MPLS Experimental Field Value" section.
The multi-VC mode functionality described in this document is used in conjunction with the Cisco Enhanced ATM Port Adapter (PA-A3) on a Cisco 7200 series router or a Cisco 7500 series router.
Benefits
The MPLS QoS Multi-VC Mode feature provides the following significant benefits:
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Tag Switching/MPLS Terminology
Table 2 lists existing tag switching terms and the corresponding MPLS IETF terms used in this document and other related Cisco publications.
MPLS QoS Support in an MPLS Network
Several different possibilities exist for using MPLS QoS in an MPLS-enabled networking environment. The method you choose depends on whether the core of the network contains label switching routers (LSRs) or ATM label switch routers (ATM-LSRs). In either case, the QoS services provided are the same (the CAR, WRED, and CBWFQ services described in Table 1).
This section describes how LSRs and ATM-LSRs can be deployed to take advantage of QoS functions in an MPLS network:
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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. Edge LSRs can operate at either the ingress or the egress side of an MPLS network, as described below.
At the ingress side of an MPLS network, LSRs process packets as follows:
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In either case, the edge LSR enforces the defined differentiation by continuing to employ WRED or CBWFQ on every ingress router.
At the egress side of an MPLS network, LSRs process packets as follows:
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LSRs Used in the Core of an MPLS Network
LSRs used in the core of an MPLS network are usually Cisco 12000 series routers or Cisco 7500 series routers running MPLS software. Such routers process packets as follows:
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LSRs used in the core of an MPLS network implement the multiple LVC model. In this model, one label is assigned for each service class for each destination.
The operation of a core LSR is the same as that described in the preceding section for an edge LSR, except that the output of the core LSR is directed to an ATM interface.
WRED is used to define service classes and determine discard policy during periods of network congestion. CBWFQ is used to define the amount of bandwidth available for each class of service, enabling MPLS packets to be scheduled for transmission by traffic class during periods of network congestion.
ATM-LSRs Used in the Core of an MPLS Network
ATM-LSRs in the core of a service provider MPLS network also implement the multiple LVC model. Such devices differentiate classes using weighted fair queuing (WFQ) techniques, which cause packets to be discarded intelligently during periods of network congestion to stabilize network behavior.
By means of a Cisco 7200 or Cisco 7500 router that incorporates the PA-A3 Enhanced ATM port adapter (see Figure 2), the service provider can configure the policy map to set the cell loss priority (CLP) bit in the header of ATM cells traversing the network, based on a matched value in the EXP field of the IP packet header. To effect the setting of the CLP bit in ATM cell headers, the service provider executes a set atm-clp command on an upstream router in the service provider's MPLS network. See the "set atm-clp" section for a description of this command.
The service provider can choose to set the CLP bit, as described above. Based on the setting of the most significant bit of the EXP field in the IP packet header, the ATM-LSR in the core of the service provider network can use the CLP bit to preferentially discard ATM cells during periods of congestion. Thus, setting the CLP bit in the header of ATM cells traversing the service provider's network ensures consistent packet/ATM cell discard treatment among the IP routers and ATM switches in the network.
On an IP router, the WRED congestion avoidance algorithm discards packets based on one of eight different values that can be assigned using the two least significant bits (LSBs) of the EXP field in the IP packet header. The values assigned to these two bits of the EXP field are used to define the packet's class, while the most significant bit (MSB) of the field is used to differentiate whether a packet entering the service provider network from a customer is "in rate" or "out of rate." Thus, the MSB of the EXP field enables the user to establish a desired WRED profile, causing packets to be discarded more aggressively during congestion conditions, provided that such packets are marked as being "out of rate."
As a necessary precondition, IP packets can be marked on the input interface of an edge router to ensure desired packet discard behavior in the event of congestion on the router's output interface. Similarly, for ATM cells traversing the core of the service provider's network, appropriate cell discard activity can be ensured by setting the CLP bit in ATM cell headers as the cells pass through a given ATM-LSR into the core of the service provider's network.
Thus, the CLP mechanism can be used to ensure that the ATM switches in the core of the service provider's network exhibit the same discard behavior as the routers on the edge of the network. The only difference is that the edge routers deal with IP packets, while the core switches deal with ATM cells.
ATM Switches Used Without MPLS Enabled
When the core network uses ATM switches and the edge of the network uses MPLS-enabled edge LSRs, the edge LSRs are interconnected through a mesh of ATM Forum permanent virtual circuits (PVCs) involving constant bit rate (CBR) traffic, variable bit rate (VBR) traffic, or unspecified bit rate (UBR) traffic over the ATM core switches. The edge LSRs invoke WFQ on a per-VC basis to provide differentiation based on the delay characteristics of each type of QoS traffic multiplexed onto the ATM Forum PVC. Optionally, WRED can also be used on a per-VC basis to manage packet drop priority between classes when congestion occurs on the edge LSR.
Using MPLS QoS in ATM Backbone
You realize the following benefits when you use MPLS QoS in a backbone consisting of ATM switches running MPLS:
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Related Features and Technologies
You can use MPLS QoS with:
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Related Documents
For additional information about MPLS functionality running on Cisco routers or switches in an MPLS environment, consult the following documentation:
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Supported Platforms
The MPLS Class of Service Multi-VC Mode feature is supported in Cisco IOS Release 12.2(4)T on the following platforms that are equipped with the Enhanced Asynchronous Transfer Mode (ATM) Port Adapter (ATM PA-A3):
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The ATM PA-A3 is a single-port, single- and dual-wide ATM port adapter used with the Cisco 7200 and 7500 series routers. It is designed with a high-performance, dual segmentation and reassembly (SAR) architecture with local buffer memory.
A Cisco 7200 series router or a Cisco 7500 series router equipped with an ATM PA-A3 port adapter can interoperate in multi-VC mode with the following Cisco ATM switches located in the core of an MPLS network:
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The MPLS QoS Multi-VC Mode feature is also supported on the Cisco MGX 8850 switch with the Cisco MGX 8850 Route Processor Module (RPM-PR).
Determining Platform Support Through Feature Navigator
Cisco IOS software is packaged in feature sets that support specific platforms. To get updated information regarding platform support for this feature, access Feature Navigator. Feature Navigator dynamically updates the list of supported platforms as new platform support is added for the feature.
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.
Feature Navigator is updated regularly when major Cisco IOS software releases and technology releases occur. For the most current information, go to the Feature Navigator home page at the following URL:
Supported Standards, MIBs, and RFCs
Standards
No new or modified standards are supported by this feature.
MIBs
No new or modified MIBs are supported by this feature.
RFCs
No new or modified RFCs are supported by this feature.
Prerequisites
To use MPLS QoS to full advantage in your network, the following functionality must be supported:
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IP packets travel through the core of an MPLS-enabled service provider network by means of multiple, label switched paths (LSPs), also known as label virtual circuits (LVCs), that are automatically established for each IP destination prefix. A standard IP access control list (ACL) is used to specify the number of traffic classes per IP destination, and hence the number of LVCs that will be created.
If there are multiple, equal cost paths through an ATM network, it is possible that each LVC relating to the same destination could take a different path through the network, because each LVC could be set up along an alternate, equal cost path. For example, if four equal cost paths exist through the network, the first LVC would be set up along the first path, the second LVC would be set up along the second path, and so forth. There is no guarantee, however, that each LVC would be set up along a parallel path in the network, nor is there any requirement that each LVC be set up in such a manner.
Each MPLS-enabled ATM interface in the service provider network, including each ATM edge interface and each ATM router/switch interface within the core of the network, provides QoS support in a manner similar to that provided for IP packet interfaces.
IP packets transiting the service provider's MPLS-enabled network are treated with the same priorities as afforded to ATM traffic. Accordingly, MPLS QoS multi-VC mode functionality is virtually indistinguishable from the QoS support provided for IP packet interfaces.
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Configuration Tasks
The following sections describe configuration tasks for using the MPLS QoS multi-VC mode feature:
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Configuring Cisco Express Forwarding
Cisco Express Forwarding (CEF) is a prerequisite for using MPLS in the core of a network; CEF must be running on all the routers in the MPLS network. To enable CEF on the routers in an MPLS network, issue the appropriate command on each device, as indicated in Table 3.
Table 3 Cisco Express Forwarding Configuration Commands
Cisco 7200 series router
ip cef
Cisco 7500 series router
ip cef distributed
Optionally Setting the MPLS Experimental Field Value
Figure 1 is a representation of an MPLS service provider network that connects two hosts of a customer's IP network. This network topology provides a framework for this section (and subsequent sections) in which the configuration tasks associated with using the MPLS QoS multi-VC mode feature are described.
Figure 1 MPLS Network Connecting Hosts in an IP Network
The ability to optionally set the MPLS experimental (EXP) field of the label header upon entry of a customer IP packet into an MPLS network has no direct connection to the MPLS QoS multi-VC mode feature per se. However, if the service provider wants to preserve the IP precedence value in the IP type-of-service (TOS) byte in the header of an incoming IP packet for any reason (such as for managing queues or selecting LVCs based on the value of the EXP field), the ability to manipulate the EXP field provides such flexibility.
By default, the IP precedence field in the header of incoming IP packets is copied into the MPLS EXP field in the label header upon entry of IP packets into the service provider's MPLS network. This default action enables IP packets to be differentiated into queues (for congestion management purposes) and to be directed to appropriate LVCs (for transmission of customer data through the MPLS network). Thus, if the IP precedence field is set, either on the edge router in the MPLS network or on some other upstream device, the incoming customer IP packets are assured of using the appropriate LVCs for data transport through the service provider network.
Optionally, you can set the MPLS EXP field value in customer IP packets arriving at the provider edge router (the PE1 ingress label switching router in Figure 1) by means of modular QoS CLI commands or CAR commands executed on that edge router. This action establishes a specified level of service for customer data traversing the service provider's MPLS network, while, at the same time, preserving the value of the IP precedence field in the incoming customer IP packets.
By assigning any one of eight different values to the EXP field (see the "Classifying Packets" section), you can mark each incoming IP packet for transport through the service provider network according to such packet attributes as packet rate and packet type.
By classifying packets, you can establish the relative priority of packets for discard purposes if congestion is experienced within the service provider network. The "Packet Prioritization" section discusses in more detail the attributes used in determining the relative priority of packets for congestion management purposes.
Classifying Packets
To classify IP packets, the PE1 ingress label switching router (LSR) in the service provider network (see Figure 1) must be appropriately configured. When so configured, customer IP packets received at the ingress router are propogated through the service provider network as MPLS packets.
You can use either of two methods to classify IP packets at the ingress LSR in the service provider's MPLS network:
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Packet Prioritization
During Step 1 of the configuration process (described in the "Using Modular QoS CLI to Configure Ingress Label Switching Router" section and the "Using CAR to Configure Ingress Label Switching Router" section), customer IP packets are classified according to the following attributes:
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Based on one or more of the above attributes, packets can be identified as Voice over IP (VoIP) traffic or File Transfer Protocol (FTP) traffic. This packet classification/marking process determines the packet's relative priority during transit through the service provider network, particularly amidst network congestion conditions.
The SLA in effect for each customer of the service provider network specifies how much bandwidth the service provider agrees to make available to each customer. To comply with the agreement, the customer must not exceed a specified traffic rate. Packets are considered to be either in-rate or out-of-rate per the SLA. Thus, during periods of congestion in the service provider network, the potential exists for out-of-rate packets to be discarded more aggressively.
Using Modular QoS CLI to Configure Ingress Label Switching Router
To use the modular QoS CLI to configure the ingress LSR (PE1 in Figure 1) appropriately for multi-VC mode functionality, perform the following steps:
Step 1
Step 2
Step 3
The following sections describe in detail how to accomplish the generalized steps outlined above.
Configuring a Class Map to Classify IP Packets
To configure a class map on the ingress LSR, use the following commands:
In the following example, all packets that contain IP precedence 4 are matched by the class-map name IP_prec4:
Router(config)# class-map IP_prec4 Router(config-c-map)# match ip precedence 4 Router(config-c-map)# endConfiguring a Policy Map to Mark MPLS EXP Field
To configure a policy map to mark the MPLS EXP field in IP packets arriving at the ingress LSR, use the following commands:
In the following example, the MPLS EXP field of each IP packet that matches class-map IP_prec4 is set to a value of 5:
Router(config)# policy-map set_experimental_5 Router(config-p-map)# class IP_prec4 Router(config-p-map-c)# set mpls experimental 5 Router(config-p-map-c)# endConfiguring Input Interface to Attach Service Policy
To configure the input interface of the ingress LSR to attach the service policy, use the following steps:
In the following example, the service policy set_experimental_5 is attached to the specified Ethernet input interface (et 1/0/0):
Router(config)# interface et 1/0/0 Router(config-if)# service-policy input set_experimental_5 Router(config-if)# endUsing CAR to Configure Ingress Label Switching Router
To use CAR to configure the ingress LSR (PE1 in Figure 1) for multi-VC mode functionality, perform the following steps:
Step 1
Step 2
The following sections describe in detail how to accomplish the generalized steps outlined above.
Configuring Rate-Limit Access List for Classifying IP Packets
To configure a rate-limit access list for classifying IP packets arriving at the ingress LSR, perform the following steps:
Step 1
Specifies the criteria to be matched.
Step 2
Exits the global configuration mode.
In the following example, all packets containing IP precedence value 4 are matched by the rate-limit access list 24:
Router(config)# access-list rate-limit 24 4 Router(config)# endConfiguring Rate-Limit on Input Interface to Mark MPLS Packets
To configure a rate-limit on an input interface to mark MPLS packets on the ingress LSR, perform the following steps:
In the following example, the MPLS EXP field is set to 4 on output of packets if input IP packets match the access-list and conform to the packet rate. The MPLS EXP field is set to 0 if packets match access list 24 and exceed the input rate.
Router(config)# interface et 1/0/0 Router(config-if)# rate-limit input access-group rate-limit 24 8000 8000 8000 conform-action set-mpls-exp-transmit 4 exceed-action set-mpls-exp-transmit 0 Router(config-if)# endConfiguring Class of Service for IP Packets on Output
The class of service for IP packets exiting the service provider network is determined by information carried in the header of each IP packet. For configuration details, refer to the Cisco IOS Quality of Service Solutions Configuration Guide.
Configuring MPLS QoS in Core of ATM Network
The following sections describe how to configure MPLS QoS in the core of an ATM network.
Configuring Multi-VC Mode in MPLS-Enabled Network
To configure multi-VC mode in an MPLS-enabled network, issue the following commands:
Step 1
Router(config)# interface type number mplsConfigures an ATM MPLS subinterface.
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Assigns an IP address to the subinterface.
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Enables ATM multi-VC mode on the subinterface. This step results in the creation of the default QoS map shown in Table 4.
Step 4
Enables MPLS on the ATM subinterface.
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Router(config-subif)# mpls label-protocol ldpConfigures LDP, rather than TDP, as the label distribution protocol.
If you do not configure a QoS map and apply it to a destination by means of a prefix map, enabling the ATM multi-VC mode on a subinterface (as done in Step 3 above) results in the creation of the default QoS map shown in Table 4. This default action creates four LVCs (Available, Standard, Premium, and Control) for each destination, and the two least significant bits of the EXP field determine the LVC to which the IP packets will be directed.
Table 4 Default QoS Map
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Available
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Control
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Available
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Control
Configuring Multi-VCs Using the QoS-Map Function
If you choose to not use the default QoS map for configuring label VCs, you can configure fewer label VCs by using the QoS map function. To use this function, issue the following commands:
Configuring Queueing Functions on Router Output Interfaces
Configuring CBWFQ on Cisco 7200/7500 Series and Cisco MGX RPM-PR Router Interfaces
To configure class-based weighted fair queueing (CBWFQ) functionality on a Cisco 7200 or 7500 series router interface or on the router interface of a Cisco MGX Route Processor Module (RPM-PR) in the Cisco MGX 8850 or 8950 switch, issue the following commands:
Configuring WRED on Cisco 7200/7500 Series or Cisco MGX RPM-PR Router Interfaces
To configure weighted random early detection (WRED) functionality on a Cisco 7200 or 7500 series router interface or on the router interface of a Cisco MGX Route Processor Module (RPM-PR) in the Cisco MGX 8850 or 8950 switch, issue the following commands:
Setting the ATM-CLP Bit on PA-A3 Interfaces
To set the atm-clp bit in ATM cells exiting from a PA-A3 (Enhanced ATM Port Adapter) interface incorporated into a Cisco 7200 or Cisco 7500 router, issue the following commands on the router.
Verifying QoS Configuration on ATM Interfaces
To verify MPLS QoS configuration on ATM interfaces, use the following commands:
Configuration Examples
Figure 2 is a sample network topology for which MPLS QoS multi-VC mode functionality has been configured for Cisco 7200 series routers in a customer IP network and a service provider MPLS network. IP and MPLS configuration examples for the following network components are provided in this section:
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Figure 2 Configuring MPLS QoS Multi-VC Mode Functionality on IP and MPLS Network Devices
Running IP on Customer Edge Router 1 (CE1)
The following sample output shows how IP has been configured to run on customer edge router 1 (CE1) shown in Figure 2:
interface Loopback0ip address 11.11.11.11 255.255.255.255!interface POS3/2ip address 31.0.0.1 255.0.0.0no ip directed-broadcastcrc 16clock source internal!router bgp 101no synchronizationbgp log-neighbor-changesnetwork 11.11.11.11 mask 255.255.255.255network 31.0.0.0redistribute connectedredistribute staticneighbor 31.0.0.2 remote-as 100neighbor 31.0.0.2 advertisement-interval 5no auto-summaryRunning IP on Customer Edge Router 2 (CE2)
The following sample output shows how IP has been configured to run on the customer edge router 2 (CE2) shown in Figure 2:
interface Loopback0ip address 10.10.10.10 255.255.255.255!interface POS3/2ip address 31.0.0.2 255.0.0.0no ip directed-broadcastcrc 16!router ospf 100log-adjacency-changesauto-cost reference-bandwidth 10000redistribute bgp 102passive-interface POS3/2passive-interface POS5/0network 10.0.0.0 0.255.255.255 area 100!router bgp 102no synchronizationbgp log-neighbor-changesnetwork 10.0.0.0network 31.0.0.0redistribute connectedredistribute staticredistribute ospf 100neighbor 31.0.0.1 remote-as 100neighbor 31.0.0.1 advertisement-interval 5no auto-summaryRunning MPLS on Provider Edge Router 1 (PE1)
The following sample output shows how MPLS has been configured to run on provider edge router 1 (PE1) shown in Figure 2:
ip cef!class-map match-all exp0match mpls experimental 0 4class-map match-all exp1match mpls experimental 1 5class-map match-all exp2match mpls experimental 2 6class-map match-all exp3match mpls experimental 3 7class-map match-all acl101match access-group 101class-map match-all acl102match access-group 102!policy-map atm_outputclass exp0bandwidth percent 10class exp1bandwidth percent 25class exp2bandwidth percent 20class exp3bandwidth percent 20!policy-map input_intclass acl101police cir 64000 bc 2000 conform-action set-mpls-exp-transmit 2 exceed-action set-mpls-exp-transmit 1class acl102police cir 32000 bc 1500 conform-action set-mpls-exp-transmit 3 exceed-action drop!ip vrf test1rd 100:1route-target export 100:1route-target import 100:1route-target import 100:2no ip dhcp-client network-discoveryno mgcp timer receive-rtcpcall rsvp-sync!interface Loopback0ip address 12.12.12.12 255.255.255.255!interface ATM1/0.1 tag-switchingip unnumbered Loopback0service-policy output atm_outputno ip mroute-cachetag-switching atm multi-vctag-switching atm vpi 2-5tag-switching ip!interface POS 6/0service-policy input input_intip vrf forwarding test1ip address 31.0.0.2 255.0.0.0clock source internal!router ospf 100log-adjacency-changesredistribute connected subnetspassive-interface POS6/0network 12.0.0.0 0.255.255.255 area 100!router bgp 100no synchronizationno bgp default ipv4-unicastbgp log-neighbor-changesredistribute staticneighbor 14.14.14.14 remote-as 100neighbor 14.14.14.14 update-source Loopback0!address-family ipv4 vrf test1redistribute connectedneighbor 30.0.0.1 remote-as 101neighbor 30.0.0.1 activateneighbor 30.0.0.1 advertisement-interval 5no auto-summaryno synchronizationexit-address-family!address-family vpnv4neighbor 14.14.14.14 activateneighbor 14.14.14.14 send-community extendedbgp scan-time import 5exit-address-family!access-list 101 permit ip host 11.11.11.11 anyaccess-list 102 permit ip host 31.0.0.1 anyRunning MPLS on Provider Edge Router 2 (PE2)
The following sample output shows how MPLS has been configured to run on provider edge router 2 (PE2) shown in Figure 2:
ip cef!class-map match-all exp0match mpls experimental 0 4class-map match-all exp1match mpls experimental 1 5class-map match-all exp2match mpls experimental 2 6class-map match-all exp3match mpls experimental 3 7class-map match-all acl101match access-group 101class-map match-all acl102match access-group 102!policy-map atm_outputclass exp0bandwidth percent 10class exp1bandwidth percent 25class exp2bandwidth percent 20class exp3bandwidth percent 20!policy-map input_intclass acl101police cir 64000 bc 2000 conform-action set-mpls-exp-transmit 2 exceed-action set-mpls-exp-transmit 1class acl102police cir 32000 bc 1500 conform-action set-mpls-exp-transmit 3 exceed-action drop!ip vrf test2rd 100:2route-target export 100:2route-target import 100:2route-target import 100:1no ip dhcp-client network-discoveryno mgcp timer receive-rtcpcall rsvp-sync!interface Loopback0ip address 14.14.14.14 255.255.255.255!interface ATM5/0.1 tag-switchingip unnumbered Loopback0service-policy output atm_outputno ip mroute-cachetag-switching atm multi-vctag-switching atm vpi 2-5tag-switching ip!interface POS6/0service-policy input input_intip vrf forwarding test2ip address 31.0.0.1 255.0.0.0clock source internal!router ospf 100log-adjacency-changesauto-cost reference-bandwidth 10000redistribute connected subnetspassive-interface POS6/0network 14.0.0.0 0.255.255.255 area 100!router bgp 100no synchronizationno bgp default ipv4-unicastbgp log-neighbor-changesredistribute staticneighbor 12.12.12.12 remote-as 100neighbor 12.12.12.12 update-source Loopback0!address-family ipv4 vrf test2redistribute connectedneighbor 31.0.0.2 remote-as 102neighbor 31.0.0.2 activateneighbor 31.0.0.2 advertisement-interval 5no auto-summaryno synchronizationexit-address-family!address-family vpnv4neighbor 12.12.12.12 activateneighbor 12.12.12.12 send-community extendedbgp scan-time import 5exit-address-family!access-list 101 permit ip host 10.10.10.10 anyaccess-list 102 permit ip host 31.0.0.2 anyCommand Reference
This section describes the commands for configuring the MPLS QoS multi-VC mode functionality on Cisco 7200/7500 series routers for Cisco IOS Release 12.2(4)T:
Other MPLS QoS CLI commands are documented in the Cisco IOS Release 12.2 command reference publications.
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 | exp | mask mask}
no access-list rate-limit acl-index {precedence | mac-address | exp | mask mask}
Syntax Description
Defaults
No CAR access lists are configured.
Command Modes
Global configuration
Command History
Usage Guidelines
Use this command to classify packets by the specified IP precedence, MAC address, or MPLS experimental field values for a particular CAR access list. You can then apply CAR policies, using the rate-limit command, to individual rate-limit access lists. This causes packets with different IP precedences, MAC addresses, or MPLS EXP field values to be 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 overwrites the previous command.
Use the mask keyword to assign multiple IP precedences or MPLS EXP field values to the same rate-limit list. To ascertain the mask value, perform the following steps:
Step 1
Step 2
Step 3
Step 4
A mask of FF matches any precedence, and 00 does not match any precedence.
Examples
In the following example, MPLS EXP fields with the value of 7 are assigned to the rate-limit access list 200:
Router(config)# access-list rate-limit 200 7You can then use the rate-limit access list in a rate-limit command so that the rate limit is applied only to packets matching the rate-limit access list.
Router(config)# interface atm4/0.1 mplsRouter(config-if)# rate-limit input access-group rate-limit 200 8000 8000 8000 conform-action set-mpls-exp-transmit 4 exceed-action set-mpls-exp-transmit 0Related Commands
Configures committed access rate (CAR) and distributed CAR (DCAR) policies.
show access-list rate-limit
Displays information about rate-limit access lists.
match mpls experimental
To configure a class map to use the specified value of the EXP field as a match criterion, use the match mpls experimental class map configuration command. To remove the EXP field match criterion from a class map, use the no form of this command.
match mpls experimental number
no match mpls experimental number
Syntax Description
number
The EXP field value (any number from 0 to 7, and they can be space-delimited, for example, 3 4 7) to be used as a match criterion.
Defaults
This command has no default behavior or values.
Command Modes
Class map configuration
Command History
Usage Guidelines
For class-based weighted fair queueing (CBWFQ), you define traffic classes based on match criteria including input interfaces, access control lists (ACLs), protocols, QoS labels, and EXP field values. Packets satisfying the match criteria for a class constitute the traffic for that class.
The match mpls experimental command specifies the name of an EXP field value to be used as the match criterion against which packets are checked to determine if they belong to the class specified by the class map.
To use the match mpls experimental command, you must first enter the class-map command to specify the name of the class whose match criteria you want to establish. After you identify the class, you can use one of the following commands to configure its match criteria:
•
•
•
•
If you specify more than one command in a class map, only the last command entered applies. The last command overrides the previously entered commands.
Examples
The following example specifies a class map called eth1 and configures the MPLS values of 1 and 2 to be used as the match criterion for this class:
Router(config)# class-map eth1Router(config-cmap)# match mpls experimental 1 2Command History
class-map
Creates a class map to be used for matching packets to a specified class.
mpls atm multi-vc
To configure a router subinterface to create one or more label VCs over which packets of different classes are sent, use the mpls atm multi-vc ATM subinterface submode command. Use the no form of the command to disable this feature.
mpls atm multi-vc
no mpls atm multi-vc
Syntax Description
This command has no optional keywords or arguments.
Defaults
This command has no default behavior or values.
Command Modes
ATM subinterface submode
Command History
Usage Guidelines
This command is valid only on ATM MPLS subinterfaces.
Examples
The following commands configure interface a2/0/0.1 on the router for MPLS QoS multi-VC mode:
Router# configure terminalEnter configuration commands, one per line. End with CNTL/Z.Router(config)# interface ATM2/0/0.1 mplsRouter(config-subif)# mpls atm multi-vcRouter(config-subif)# exitRouter(config)# exitRelated Commands
mpls cos-map
To create a class map that specifies how classes map to label VCs when they are combined with a prefix map, use the mpls cos-map global configuration command.
mpls cos-map cos-map
Syntax Description
Defaults
This command has no default behavior or values.
Command Modes
Global configuration
Command History
Examples
The following example shows how to create a class map:
Router(config)# mpls cos-map 55Router(config-mpls-cos-map)# class 1 premiumRouter(config-mpls-cos-map)# exitRouter(config)#Related Commands
Displays the QoS map used to assign a quantity of label VCs and the associated class of service for those label VCs.
mpls prefix-map
To configure a router to use a specified QoS map when a label destination prefix matches the specified access list, use the mpls prefix-map ATM subinterface submode command.
mpls prefix-map prefix-map access-list access-list cos-map cos-map
Syntax Description
prefix-map
A unique number for a prefix map.
access-list access list
A unique number for a simple IP access list.
cos-map cos-map
A unique number for a QoS map.
Defaults
This command has no default behavior or values.
Command Modes
ATM subinterface submode
Command History
Usage Guidelines
This is a global command that links an access list to a QoS map.
Examples
In the following example, an access list is linked to a QoS map:
Router(config-subif)# mpls prefix-map 55 access-list 55 cos-map 55Related Commands
Shows the prefix map used to assign a QoS map to network prefixes that match a standard IP access list.
rate-limit
To configure CAR and DCAR policies, use the rate-limit interface configuration command. To remove the rate limit from the configuration, use the no form of this command.
rate-limit {input | output} [access-group [rate-limit] acl-index] bps
burst-normal burst-max conform-action conform-action exceed-action exceed-actionno rate-limit {input | output}[access-group [rate-limit] acl-index] bps
burst-normal burst-max conform-action conform-action exceed-action exceed-actionSyntax Description
Defaults
CAR and DCAR are disabled.
Command Modes
Interface configuration
Command History
Usage Guidelines
Use this command to configure your CAR policy on an interface. To specify multiple policies, enter this command once for each policy.
CAR and DCAR can be configured on an interface or subinterface.
Examples
In the following example, the rate is limited by the application in question:
•
rate-limit input rate-limit access-group 101 20000000 24000 32000 conform-actionset-mpls-exp-transmit 5 exceed-action set-mpls-exp-transmit 0access-list 101 permit tcp any any eq www•
rate-limit input access-group 102 10000000 24000 32000conform-action set-mpls-exp-transmit 5 exceed-action dropaccess-list 102 permit tcp any any eq ftp•
rate-limit input 8000000 16000 24000 conform-action set-mpls-exp-transmit 5exceed-action dropNotice that two access lists are created to classify the Web and FTP traffic so that they can be handled separately by the CAR feature.
Router(config)# interface Hssi0/0/0Router(config-if)# description 45Mbps to R2Router(config-if)# rate-limit input rate-limit access-group 101 20000000 24000 32000conform-action set-mpls-exp-transmit 5 exceed-action set-mpls-exp-transmit 0Router(config-if)# rate-limit input access-group 102 10000000 24000 32000conform-action set-mpls-exp-transmit 5 exceed-action dropRouter(config-if)# rate-limit input 8000000 16000 24000 conform-actionset-mpls-exp-transmit 5 exceed-action dropRouter(config-if)# ip address 200.200.14.250 255.255.255.252!Router(config-if)# access-list 101 permit tcp any any eq wwwRouter(config-if)# access-list 102 permit tcp any any eq ftpIn the following example, the MPLS EXP field is set and the packet is transmitted:
Router(config)# interface FastEtheret1/1/0Router(config-if)# rate-limit input 8000 1000 1000 access-group conform-actionset-mpls-exp-transmit 5 exceed-action set-mpls-exp-transmit 5Related Commands
set atm-clp
To control the cell loss priority (CLP) bit setting on Cisco routers, use the set atm-clp policy map class command.
set atm-clp
Syntax Description
This command has no arguments or keywords.
Defaults
The CLP bit is automatically set to 0 when Cisco routers convert IP packets into ATM cells for transmission through MPLS-aware ATM networks.
Command Modes
Policy map class
Command History
12.1(5)T
This command was introduced.
12.2(2)T
This command was integrated into Cisco IOS Release 12.2(2)T.
Usage Guidelines
To disable this command, remove the service policy from the interface.
Examples
The following example illustrates setting the CLP bit using the set atm-clp command in the policy map:
Router(config)# class-map ip-precRouter(config-cmap)# match ip precedence 0 1Router(config-cmap)# exitRouter(config)# policy-map atm-clp-setRouter(config-pmap)# class ip-precRouter(config-pmap-c)# set atm-clpRouter(config-pmap-c)# exitRouter(config-pmap)# exitRouter(config)# interface atm 1/0/0.1Router(config)# service-policy output bearRelated Commands
set mpls experimental
To configure a policy to set the MPLS experimental field within the modular QoS CLI, use the set mpls experimental policy map configuration command. To disable the policy map, use the no form of this command.
set mpls experimental value
no set mpls experimental value
Syntax Description
value
Specifies the value used to set MPLS experimental field bits defined by the policy map. Valid values are 0 to 7; these values can be space-delimited (for example, 3 4 7).
Defaults
This command has no default behavior or values.
Command Modes
Policy map configuration
Command History
12.1(5)T
This command was introduced.
12.2(2)T
This command was integrated into Cisco IOS Release 12.2(2)T.
Usage Guidelines
Use the policy map to set the MPLS experimental field when it is undesirable to modify the IP precedence field.
Examples
The following example specifies a policy map named out_pmap. The policy map comprises class maps. Class map mpls_2 matches packets with MPLS experimental field 2 and resets the MPLS experimental field to 3.
Router(config)# class-map mpls_2Router(config-cmap)# match mpls experimental 2Router(config-cmap)# exitRouter(config)# policy-map out_pmapRouter(config-pmap)# class mpls_2Router(config-pmap-c)# set mpls experimental 3Router(config-pmap-c)# exitRouter(config-pmap)# exitRouter(config)#Related Commands
show mpls cos-map
To display the QoS map used to assign a quantity of label VCs and the associated class of service for those VCs, use the show mpls cos-map privileged EXEC command.
show mpls cos-map [cos-map]
Syntax Description
Defaults
Not entering a specific cos-map argument causes all cos-maps to be displayed.
Command Modes
Privileged EXEC
Command History
Examples
The following shows sample output from the show mpls cos-map command:
Router# show mpls cos-map 2cos-map 2 class tag-VC3 control2 control1 available0 availableTable 5 describes the significant fields in the sample display shown above.
Related Commands
Creates a class map specifying how classes map to label VCs when they are combined with a prefix map.
show mpls prefix-map
To show the prefix map used to assign a QoS map to network prefixes that match a standard IP access list, use the show mpls prefix-map privileged EXEC command.
show mpls prefix-map [prefix-map]
Syntax Description
Defaults
Not entering a specific prefix-map argument causes all prefix-maps to be displayed.
Command Modes
Privileged EXEC
Command History
Examples
The following is sample output from the show mpls prefix-map command:
Router# show mpls prefix-map 2prefix-map 2 access-list 2 cos-map 2Table 6 describes the fields in the sample output shown above.
Table 6 show mpls prefix-map Command Field Descriptions
Unique number of a prefix map.
Unique number of an access list.
Unique number of a QoS map.
Related Commands
Configures a router to use a specified QoS map when a label destination prefix matches the specified access-list.
Debug Commands
This section describes the following command for using the MPLS QoS multi-VC mode capabilities supported in this release:
Other CLI commands used in conjunction with MPLS QoS functionality are documented in the Cisco IOS Release 12.2 command reference publications.
debug mpls atm-cos
To display ATM label VC bind or request activity that is based on the configuration of a QoS map, use the debug mpls atm-cos ATM subinterface submode command.
debug mpls atm-cos [bind | request]
Syntax Description
bind
Specifies debug information about bind responses for a vc path.
request
Specifies debug information about bind requests for a vc path.
Defaults
This command has no default behavior or values.
Command Modes
ATM subinterface submode
Command History
Examples
The following command sequence demonstrates how to obtain sample output from the debug mpls atm-cos command.
First, display the MPLS forwarding table to see which prefixes are associated with a single LVC, as shown below:
Router# show mpls forwardingLocal Outgoing Prefix Bytes tag Outgoing Next Hoptag tag or VC or Tunnel Id switched interface26 28 17.17.17.17/32 0 PO6/0 point2point27 Pop tag 11.11.11.11/32 1560 PO6/0 point2point28 27 16.16.16.16/32 0 PO6/0 point2point29 30 92.0.0.0/8 0 PO6/0 point2point30 Pop tag 95.0.0.0/8 2600 PO6/0 point2point31 2/34 10.10.10.10/32 0 AT2/0.1 point2point32 Pop tag 14.14.14.14/32 0 Fa5/0 91.0.0.133 Pop tag 90.0.0.0/8 0 Fa5/0 91.0.0.134 Pop tag 96.0.0.0/8 0 Fa5/0 91.0.0.12/36 96.0.0.0/8 0 AT2/0.1 point2point35 35 93.0.0.0/8 0 PO6/0 point2point36 36 12.12.12.12/32 0 PO6/0 point2point37 37 15.15.15.15/32 0 PO6/0 point2point38 37 18.18.18.18/32 0 Fa5/0 91.0.0.139 39 97.0.0.0/8 540 PO6/0 point2point40 40 98.0.0.0/8 0 PO6/0 point2pointSecond, enable debugging of request and bind events, as shown in the command sequence below:
Router# debug mpls atm-cos ?bind Bind response for VC pathrequest Requests for VC binds pathRouter# debug mpls atm-cos requestATM TAGCOS VC requests debugging is onRouter# debug mpls atm-cos bindATM TAGCOS Bind response debugging is onThird, configure an MPLS ATM subinterface for multi-VC mode. The corresponding request and bind events are displayed, as shown below:
Router# conf terminalEnter configuration commands, one per line. End with CNTL/Z.Router(config)# int a2/0.1Router(config-subif)# mpls atm multi-vcRouter(config-subif)# endRouter#19:59:14:%SYS-5-CONFIG_I:Configured from console by consoleRouter#19:59:24:TAGCOS-REQ:vc request 10.10.10.10/32, available19:59:24:TAGCOS-REQ:vc request 10.10.10.10/32, standard19:59:24:TAGCOS-REQ:vc request 10.10.10.10/32, premium19:59:24:TAGCOS-REQ:vc request 10.10.10.10/32, control19:59:24:TAGCOS-REQ:vc request 96.0.0.0/8, available19:59:24:TAGCOS-REQ:vc request 96.0.0.0/8, standard19:59:24:TAGCOS-REQ:vc request 96.0.0.0/8, premium19:59:24:TAGCOS-REQ:vc request 96.0.0.0/8, controlTAGCOS-REQ/TCATM:11.11.11.11/32,len=4352,band=1099528405504,class=0x700TAGCOS-REQ/TCATM:12.12.12.12/32,len=4352,band=2199040033280,class=0x700TAGCOS-REQ/TCATM:13.13.13.13/32,len=4352,band=3298551661056,class=0x700TAGCOS-REQ/TCATM:14.14.14.14/32,len=4352,band=4398063288832,class=0x700TAGCOS-REQ/TCATM:15.15.15.15/32,len=4352,band=5497574916608,class=0x700TAGCOS-REQ/TCATM:16.16.16.16/32,len=4352,band=6597086544384,class=0x700TAGCOS-REQ/TCATM:17.17.17.17/32,len=4352,band=7696598172160,class=0x700TAGCOS-REQ/TCATM:18.18.18.18/32,len=4352,band=8796109799936,class=0x700TAGCOS-REQ/TCATM:90.0.0.0/8,len=768,band=3940649674539009,class=0x2TAGCOS-REQ/TCATM:91.0.0.0/8,len=768,band=3940649674604545,class=0x2TAGCOS-REQ/TCATM:92.0.0.0/8,len=768,band=3940649674670081,class=0x2TAGCOS-REQ/TCATM:93.0.0.0/8,len=768,band=3940649674735617,class=0x2TAGCOS-REQ/TCATM:94.0.0.0/8,len=768,band=3940649674801153,class=0x2TAGCOS-REQ/TCATM:95.0.0.0/8,len=768,band=3940649674866689,class=0x2TAGCOS-REQ/TCATM:97.0.0.0/8,len=768,band=3940649674932225,class=0x2TAGCOS-REQ/TCATM:98.0.0.0/8,len=768,band=3940649674997761,class=0x2TAGCOS-BIND:binding_ok 10.10.10.10/32,VCD=41 - control 41,41,41,41TAGCOS-BIND:binding_ok 10.10.10.10/32, Inform TFIB pidx=0, in_tag=31, idx=0x80000000TAGCOS-BIND:binding_ok 96.0.0.0/8,VCD=42 - control 42,42,42,42TAGCOS-BIND:binding_ok 96.0.0.0/8, Inform TFIB pidx=1, in_tag=34, idx=0x80000001TAGCOS-BIND:binding_ok 10.10.10.10/32,VCD=43 - premium 43,43,43,41TAGCOS-BIND:binding_ok 96.0.0.0/8,VCD=44 - premium 44,44,44,42TAGCOS-BIND:binding_ok 10.10.10.10/32,VCD=45 - standard 45,45,43,41TAGCOS-BIND:binding_ok 96.0.0.0/8,VCD=46 - standard 46,46,44,42TAGCOS-BIND:binding_ok 10.10.10.10/32,VCD=47 - available 47,45,43,41TAGCOS-BIND:binding_ok 96.0.0.0/8,VCD=48 - available 48,46,44,42Router#Router#Glossary
ATM edge LSR—A router that is connected to the ATM-LSR cloud through an LSC-ATM interface. 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 LSC-ATM interfaces. The router forwards ATM 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.
Class-based weighted fair queueing (CBWFQ)—CBWFQ extends standard WFQ functionality to provide support for user-defined traffic classes. For CBWFQ, you define traffic classes based on match criteria which include protocols, access control lists (ACLs), and input interfaces. Packets satisfying match criteria for a class constitute the traffic for that class. A queue is reserved for each class, and the traffic belonging to a class is directed to the queue for that class.
IP precedence—A 3-bit value in the ToS byte that is used for assigning precedence to IP packets.
label—A short, fixed-length construct that tells switching nodes how to forward data (packets or cells) in a network.
label-controlled ATM interface (LC-ATM interface)—An interface on a router or switch that uses label distribution procedures to negotiate label VCs.
label edge router (LER)—A router that performs label imposition at thepoint of ingress in a network.
label imposition—The process of adding the first label on a packet.
label switch—A node that forwards units of data (packets or cells) on the basis of labels carried in the packets or cells.
label switch path (LSP)—An LSP results from a series 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 packets based on the value of a label encapsulated in each 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 for label-VC traffic. Link and per-VC bandwidth sharing can be controlled by relative bandwidth configuration at the edge of the network 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).
QoS—Quality of service. A feature that provides scalable, differentiated types of service across an MPLS network.
RED—Random early detection. A congestion avoidance algorithm in which a small percentage of packets are dropped automatically when congestion is detected in the network and before the queue in question overflows completely.
ToS bits—Type of service bits. A byte in the IPv4 packet 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; the tunnel is used to direct traffic over a path different from the one that Layer 3 routing would otherwise 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 class of service (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.
