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Table Of Contents
Configuring Multiprotocol Label Switching on the Optical Services Modules
MPLS Limitations and Restrictions
MPLS QoS Limitations and Restrictions
Understanding the MPLS Experimental Field
MPLS VPN Limitations and Restrictions
MPLS VPN Memory Requirements and Recommendations
Configuring Multiprotocol Label Switching on the Optical Services Modules
This chapter describes how to configure Multiprotocol Label Switching (MPLS) and Ethernet over Multiprotocol Label Switching (EoMPLS) on the Optical Services Modules (OSMs).
This chapter consists of these sections:
Configuring MPLS
These sections describe MPLS and provides configuration information:
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MPLS Limitations and Restrictions
Understanding MPLS
MPLS uses label switching to forward packets over various link-level technologies such as Packet-over-SONET, Frame Relay, ATM, and Ethernet. Labels are assigned to packets based on groupings or forwarding equivalence classes (FECs). Packets belonging to the same FEC get similar treatment. The label is added between the Layer 2 and the Layer 3 header (in a packet environment) or in the virtual path identifier/virtual channel identifier (VPI/VCI) field (in ATM networks).
In an MPLS network, the edge router performs a label lookup of the incoming label, swaps the incoming label with an outgoing label, and sends the packet to the next hop. Labels are imposed on packets only at the ingress edge of the MPLS network and are removed at the egress edge. The core network reads the labels, applies the appropriate services, and forwards the packets based on the labels.
MPLS Support on OSMs
MPLS is supported on the following Catalyst 6000 family and Cisco 7600 series OSMs:
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MPLS Limitations and Restrictions
The following platform-specific limitations and restrictions apply to the MPLS support on the OSM modules:
Unsupported MPLS Features
Although the CLI may allow you to configure the following features, they are not supported:
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MPLS Limitations
The following MPLS limitations apply:
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Configuring MPLS
For information on configuring MPLS, refer to the Multiprotocol Label Switching on Cisco Routers feature module at this URL:
http://www.cisco.com/univercd/cc/td/doc/product/software/ios121/121newft/121t/121t5/mpls4t.htm
Configuring MPLS QoS
For information on configuring MPLS QoS, refer to the MPLS Class Of Service Enhancement feature module at this URL:
http://www.cisco.com/univercd/cc/td/doc/product/software/ios121/121newft/121t/121t5/mct1214t.htm
These sections provide configuration information for MPLS QoS:
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Unsupported MPLS QoS Commands
The following commands are not supported on the FlexWAN and the OSMs:
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Supported MPLS QoS Features
This section lists the supported MPLS QoS features.
MPLS QoS Support on FlexWAN
The following QoS features are supported on the FlexWAN modules:
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The following features are not supported:
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MPLS QoS Support on the Optical Services Modules
The following QoS features are supported on the OSMs. For information about IP QoS support on the OSMs, see Chapter 9, "Configuring QoS on the Optical Services Modules."
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MPLS QoS Limitations and Restrictions
The following limitation applies to MPLS QoS support on the Cisco 7600 series router:
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Understanding the MPLS Experimental Field
Setting the MPLS experimental field value satisfies the requirement of service providers that do not want the value of the IP precedence field modified within IP packets transported through their networks.
By choosing different values for the MPLS experimental field, you can mark packets so that packets have the priority that they require during periods of congestion.
By default, the IP precedence value is copied into the MPLS experimental field during imposition. A set mpls experimental policy can be applied on the output interface of the PE router or the input interface on a provider core (P) router.
Figure 11-1 shows an MPLS network of a service provider that connects two sites of a network belonging to a customer.
Figure 11-1 MPLS Network Connecting Two Sites of a Customer's IP Network
Configuring MPLS QoS
To configure MPLS QoS, perform the tasks described in the following sections:
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For information on configuring OSM QoS features, see Configuring QoS on the Optical Services Modules.
Configuring a Class Map to Classify MPLS Packets
To configure a class map, perform this task beginning in global configuration mode:
This example shows that all packets that contain MPLS experimental value 4 are matched by the traffic class exp4:
Router(config)# class-map exp4
Router(config-cmap)# match mpls experimental 4
Router(config-cmap)# exitConfiguring a Policy Map to Set the MPLS Experimental Field
To configure a policy map, perform this task beginning in global configuration mode:
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Creates a policy map that can be attached to one or more interfaces to specify a service policy.
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Specifies the name of the class map previously designated in the class-map command.
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Designates the value to which the MPLS bits are set if the packets match the specified policy map.
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Exits policy-map configuration mode.
1 You can also configure additional supported features, such as shaping.
This example shows that the value in the MPLS experimental field of each packet that is matched by the class-map exp4 is set to 5:
Router(config)# policy-map set_experimental_5
Router(config-pmap)# class exp4
Router(config-pmap-c)# set mpls experimental 5
Router(config-pmap-c)# exitRouter(config-pmap)# exitAttaching the Service Policy
To attach the service policy to an interface, perform this task beginning in global configuration mode:
This example shows that the service policy set_experimental_5 is attached to an POS output interface:
Router(config)# interface POS6/1
Router(config-if)# service-policy output set_experimental_5
Router(config-if)# exitVerifying QoS Operation
To verify the operation of MPLS QoS, perform this task:
Router# show policy-map interface [interface-name]
Displays detailed information about QoS.
Configuration Examples
Sample configurations provided in this section can be applied to either OSMs or FlexWAN modules supported on the Cisco 7600 series routers.
Ingress PE Router Configuration
In the following example, IP packets with IP precedence 1 entering an MPLS network are shaped to 2000000 bits per second and set to MPLS experimental field 5. When IP packets with IP precedence 0 enter the MPLS network, they are shaped to 3000000 bits per second and set to MPLS experimental field 3. When IP packets with any other IP precedence value enter the MPLS network, they are shaped to 5000000 bits per second.
Step 1
Router(config)# class-map goldRouter(config-cmap)# match mpls experimental 1Router(config-cmap)# exitRouter(config)# class-map silverRouter(config-cmap)# match mpls experimental 0Router(config-cmap)# exit
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Step 2
Router(config)# policy-map policy1Router(config-pmap)# class goldRouter(config-pmap-c)# set mpls experimental 5Router(config-pmap-c)# shape average 2000000Router(config-pmap-c)# exitRouter(config-pmap)# class silverRouter(config-pmap-c)# set mpls experimental 3Router(config-pmap-c)# shape average 3000000Router(config-pmap-c)# exitRouter(config-pmap)# class class-defaultRouter(config-pmap-c)# shape average 5000000Router(config-pmap-c)# exitRouter(config-pmap)# exitStep 3
Router(config)# interface GE-WAN7/1Router(config-if)# service-policy output policy1Step 4
Router# show policy-map interface POS6/2POS6/2service-policy output:policy1class-map:gold (match-all)0 packets, 0 bytes30 second offered rate 0 bps, drop rate 0 bpsmatch:mpls experimental 1queue size 0, queue limit 500packets output 0, packet drops 0tail/random drops 0, no buffer drops 0, other drops 0set:mpls experimental 5shape:cir 2000000, Bc 8000, Be 8000output bytes 0, shape rate 0 bpsclass-map:silver (match-all)9521 packets, 9425790 bytes30 second offered rate 3681000 bps, drop rate 1505000 bpsmatch:mpls experimental 0queue size 0, queue limit 128packets output 2845, packet drops 6676tail/random drops 6676, no buffer drops 0, other drops 0set:mpls experimental 3shape:cir 3000000, Bc 12000, Be 12000output bytes 2816550, shape rate 642000 bpsclass-map:class-default (match-any)0 packets, 0 bytes30 second offered rate 0 bps, drop rate 0 bpsmatch:any0 packets, 0 bytes30 second rate 0 bpsqueue size 0, queue limit 128packets output 0, packet drops 0tail/random drops 0, no buffer drops 0, other drops 0shape:cir 5000000, Bc 20000, Be 20000output bytes 0, shape rate 0 bpsRouter#
Configuring MPLS VPN
These sections describe how to configure MPLS VPN:
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MPLS VPN Support on OSMs
MPLS VPN is supported on the following OSMs:
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MPLS VPN Limitations and Restrictions
The following MPLS VPN limitations apply:
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MPLS VPN Memory Requirements and Recommendations
When a Cisco 7600 series router or a Catalyst 6500 series switch functions as a PE router in an MPLS VPN environment, the memory requirements that are listed in Table 11-1apply:
If the number of Internet routes, eBGP sessions, and VPNv4 routes exceed those listed in Table 11-1, upgrade to the next memory option. If you have a FlexWAN module installed in the system, the number of Internet routes, eBGP sessions, and VPNv4 routes in the configuration file must not exceed the requirement listed in the table for FlexWAN.
MPLS Per-Label Load Balancing
When the Cisco 7600 series router is configured as a P router, you can ensure traffic is distributed among equal cost paths by using the mpls load-balance per-label command to enable or disable the load balancing for tag-to-tag traffic.
When enabled, MPLS per-label load balancing ensures that traffic is balanced based on the incoming labels (per prefix) among MPLS interfaces. Each MPLS interface supports an equal number of incoming labels.
mpls load-balance per-label[no] mpls load-balance per-labelThe default is disabled.
Use the no form of the command to return to the default setting.
In the following example, MPLS per-label load balancing is enabled on a POS interface:
Router(config)# interface pos 4/1Router(config-if)# mpls load-balance per-labelYou can use the show mpls ttfib command to view the incoming label (indicated by an asterick*) that is included in the load balancer. The following shows the output of the show mpls ttfib command:
Router# show mpls ttfibLocal Outgoing Packets Tag LTL Dest. Destination OutgoingTag Tag or VC Switched Index Vlanid Mac Address Interface4116 21 0 0xE0 1020 0000.0400.0000 PO4/1*34 0 0x132 1019 00d0.040d.380a GE5/345 0 0xE3 4031 0000.0430.0000 PO4/44117 16 0 0x132 1019 00d0.040d.380a GE5/3*17 0 0xE0 1020 0000.0400.0000 PO4/118 0 0xE3 4031 0000.0430.0000 PO4/44118 21 0 0xE0 1020 0000.0400.0000 PO4/1*56 0 0xE3 4031 0000.0430.0000 PO4/44119 35 0 0xE3 4031 0000.0430.0000 PO4/4*47 0 0xE0 1020 0000.0400.0000 PO4/1Configuring MPLS VPN
For information on configuring MPLS VPN, refer to the MPLS Virtual Private Networks feature module at this URL:
http://www.cisco.com/univercd/cc/td/doc/product/software/ios120/120newft/120t/120t7/vpn_en.htm
Configuring MPLS VPN CoS
MPLS VPN supports the same set of QoS features as basic MPLS does. For information on supported QoS features and configuring MPLS VPN QoS, refer to the MPLS Class Of Service Enhancement feature module referenced in the "Configuring MPLS QoS" section.
In addition to these features, MPLS VPN also supports the set ip precedence command on the input WAN interfaces on the OSMs.
The following restrictions apply to the support for MPLS VPN CoS on the OSMs:
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Configuration Example
The following example shows how to configure CoS on an MPLS VPN:
Router# configure terminalRouter(config)# class-map match-any vpn-classRouter(config-cmap)# match ip precedence 3Router(config-cmap)# exitRouter(config)# policy-map VPN-MARKINGRouter(config-pmap)# class vpn-classRouter(config-pmap-c)# set ip precedence 5Router(config-pmap-c)# set mpls exp 5Router(config-pmap-c)# ^ZRouter# configure terminalRouter(config)# interface ge-WAN 5/4Router(config-if)# service-policy input VPN-MARKINGRouter(config-if)# ^ZRouter# show running-config interface g5/4Building configuration...Current configuration :175 bytes!interface GE-WAN5/4ip vrf forwarding TESTip address 194.3.1.3 255.255.255.0negotiation autoservice-policy input VPN-MARKINGmls qos trust dscpendRouter#Configuring EoMPLS
EoMPLS allows you to connect two VLAN networks in different locations without using bridges, routers, or switches at the VLAN locations. You can enable the MPLS backbone network to accept Layer 2 VLAN traffic by configuring the label edge routers (LERs) at both ends of the MPLS backbone.
For information about EoMPLS and how to configure it on the 4-port Gigabit Ethernet WAN (GBIC) and POS OSMs, refer to the Ethernet over MPLS Feature Module at this URL:
http://www.cisco.com/univercd/cc/td/doc/product/software/ios121/121newft/121limit/121ex/121ex8a/eompls9.htm
1 MPLS/VPN is supported in POS mode only on the 2-port OC48/1DPT OSMs.
