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Table Of Contents
Prerequisites for MPLS—Multilink PPP Support
Restrictions for MPLS—Multilink PPP Support
Information About MPLS—Multilink PPP Support
MPLS Features Supported for Multilink PPP
MPLS Layer 3 Virtual Private Network Features Supported for Multilink PPP
MPLS Quality of Service Features Supported for Multilink PPP
MPLS—Multilink PPP Support and PE-to-CE Links
MPLS—Multilink PPP Support and Core Links
MPLS—Multilink PPP Support in a CSC Network
MPLS—Multilink PPP Support in an Interautonomous System
How to Configure MPLS—Multilink PPP Support
Enabling Cisco Express Forwarding or Distributed Cisco Express Forwarding Switching
Creating a Multilink Bundle for MPLS—Multilink PPP Support
Assigning an Interface to a Multilink Bundle for MPLS—Multilink PPP Support
Disabling PPP Multilink Fragmentation
Verifying the Multilink PPP Configuration
Configuration Examples for MPLS—Multilink PPP Support
Sample MPLS—Multilink PPP Support Configurations
Sample Multilink PPP Configuration on a Cisco 7200 Series Router
Sample Multilink PPP Configuration for a Cisco 7500 Series Router
Sample Multilink PPP Configuration on an MPLS CSC PE Router
Enabling Cisco Express Forwarding or Distributed Cisco Express Forwarding: Example
Creating a Multilink Bundle for MPLS—Multilink PPP Support: Example
Assigning an Interface to a Multilink Bundle for MPLS—Multilink PPP Support: Example
Feature Information for MPLS—Multilink PPP Support
MPLS—Multilink PPP Support
First Published: December 18, 2003Last Updated: July 11, 2008The MPLS—Multilink PPP Support feature ensures that MPLS Layer 3 Virtual Private Networks (VPNs) with quality of service (QoS) can be enabled for bundled links. This feature supports Multiprotocol Label Switching (MPLS) over Multilink PPP (MLP) links in the edge (provider edge [PE]-to-customer edge [CE]) or in the MPLS core (PE-to-PE and PE-to-provider router [P]).
Service providers that use relatively low-speed links can use MLP to spread traffic across them in their MPLS networks. Link fragmentation and interleaving (LFI) should be deployed in the CE-to-PE link for efficiency, where traffic uses a lower link bandwidth (less than 768 kbps).
Finding Feature Information in This Module
Your Cisco IOS software release may not support all of the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release. To reach links to specific feature documentation in this module and to see a list of the releases in which each feature is supported, use the "Feature Information for MPLS—Multilink PPP Support" section.
Finding Support Information for Platforms and Cisco IOS and Catalyst OS Software Images
Use Cisco Feature Navigator to find information about platform support and Cisco IOS and Catalyst OS software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.
Contents
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Prerequisites for MPLS—Multilink PPP Support
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Prerequisites for MPLS—Multilink PPP Support
The MPLS—Multilink PPP Support feature requires the following:
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Table 1 lists the required port adapters and processors for the MPLS—Multilink PPP Support feature on the Cisco 7200 series routers. Table 2 lists the required port adapters and processors for the MPLS—Multilink PPP Support feature on the Cisco 7500 series routers.
Restrictions for MPLS—Multilink PPP Support
The MPLS—Multilink PPP Support feature is limited byplatform-specific restrictions that apply to the use of MLP and distributed MLP (dMLP).
For restrictions that apply to dMLP on the Cisco 7500 routers, see the Distributed Multilink Point-to-Point Protocol for Cisco 7500 Series Routers feature module.
Information About MPLS—Multilink PPP Support
This section contains information that you need to use the MPLS—Multilink PPP Support feature:
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MPLS Features Supported for Multilink PPP
The following topics provide information about MPLS features supported for MLP:
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MPLS Layer 3 Virtual Private Network Features Supported for Multilink PPP
Table 3 lists MPLS Layer 3 VPN features supported for MLP and indicates if the feature is supported on CE-to-PE links, PE-to-P links, and Carrier Supporting Carrier (CSC) CE-to-PE links.
Table 3 MPLS Layer 3 VPN Features Supported for MLP
Static routes
Supported
—1
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External Border Gateway Protocol (eBGP)
Supported
Not applicable to this configuration
Supported
Intermediate System-to-Intermediate System (IS-IS)
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Supported
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Open Shortest Path first (OSPF)
Supported
Supported
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Enhanced Interior Gateway Routing Protocol (EIGRP)
Supported
Supported
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Interprovider (Inter-AS) VPNs (with Label Distribution Protocol [LDP])
Not applicable to this configuration
Supported (MLP between Autonomous System Border routers {ASBRs])
Not applicable to this configuration
Inter-AS VPNs with IPv4 Label Distribution
Not applicable to this configuration
Supported (MLP between ASBRs]
Not applicable to this configuration
CSC VPNs (with LDP)
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Not applicable to this configuration
Supported
CSC VPNs with IPv4 label distribution
Supported
Not applicable to this configuration
Supported
External and internal BGP (eiBGP) Multipath
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Not applicable to this configuration
Internal BGP (iBGP) Multipath
Not applicable to this configuration
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Not applicable to this configuration
eBGP Multipath
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1 An em dash (—) indicates that the configuration is not supported.
MPLS Quality of Service Features Supported for Multilink PPP
Table 4 lists the MPLS QoS features supported for MLP and indicates if the feature is supported on CE-to-PE links, PE-to-P links, and CSC-CE-to-CSC-PE links.
Table 4 MPLS QoS Features Supported for MLP
Default copy of IP Precedence to EXP bits and the reverse
Supported
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Set MPLS EXP bits using the modular QoS Command Line Interface (MQC)
Supported
Supported
Supported
Matching on MPLS EXP using MQC
Supported
Supported
Supported
Low Latency Queueing (LLQ)/
Class-Based Weighted Fair Queueing (CBWFQ) supportSupported
Supported
Supported
Weighted Random Early Detection (WRED) based on EXP bits using MQC
Supported
Supported
Supported
Policer with EXP bit-marking using MQC-3 action
Supported
Supported
Supported
Support for EXP bits in MPLS accounting
Supported
Supported
Supported
1 An em dash (—) indicates that the configuration is not supported.
MPLS—Multilink PPP Support and PE-to-CE Links
Figure 1 shows a typical MPLS network in which the PE router is responsible for label imposition (at ingress) and disposition (at egress) of the MPLS traffic.
In this topology, MLP is deployed on the PE-to-CE links. The VPN routing and forwarding instance (VRF) interface is in a multilink bundle. There is no MPLS interaction with MLP; all packets coming into the MLP bundle are IP packets.
Figure 1 MLP and Traditional PE-to-CE Links
The PE-to-CE routing protocols that are supported for the MPLS—Multilink PPP Support feature are eBGP, OSPF, and EIGRP. Static routes are also supported between the CE and PE routers.
QoS features that are supported for the MPLS—Multilink PPP Support feature on CE-to-PE links are LFI, compressed Real-Time Transport Protocol (cRTP), policing, marking, and classification.
MPLS—Multilink PPP Support and Core Links
Figure 2 shows a sample topology in which MPLS is deployed over MLP on PE-to-P and P-to-P links. Enabling MPLS on MLP for PE-to-P links is similar to enabling MPLS on MLP for P-to-P links.
Figure 2 MLP on PE-to-P and P-to-P Links
You employ MLP in the PE-to-P or P-to-P links primarily so that you can reduce the number of Interior Gateway Protocol (IGP) adjacencies and facilitate the load sharing of traffic.
In addition to requiring MLP on the PE-to-P links, the MPLS—Multilink PPP Support feature requires the configuration of an IGP routing protocol and LDP.
MPLS—Multilink PPP Support in a CSC Network
Figure 3 shows a typical MPLS VPN CSC network where MLP is configured on the CSC-CE-to-CSC-PE links.
Figure 3 MLP on CSC-CE-to-CSC-PE Links with MPLS VPN Carrier Supporting Carrier
The MPLS—Multilink PPP Support feature supports MLP between CSC-CE and CSC-PE links with LDP or with EBGP IPv4 label distribution. This feature also supports LFI for an MPLS VPN CSC configuration. Figure 4 shows all MLP links that this feature supports for CSC configurations.
Figure 4 MLP Supported Links with MPLS VPN Carrier Supporting Carrier
MPLS—Multilink PPP Support in an Interautonomous System
Figure 5 shows a typical MPLS VPN interautonomous system (Inter-AS) network where MLP is configured on the PE-to-CE links.
Figure 5 MLP on ASBR-to-PE Links in an MPLS VPN Inter-AS Network
The MPLS—Multilink PPP Support feature supports MLP between ASBR links for Inter-AS VPNs with LDP and with eBGP IPv4 label distribution.
How to Configure MPLS—Multilink PPP Support
This section contains the following procedures for configuring the MPLS—Multilink PPP Support feature:
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Service providers that use relatively low-speed links can use MLP to spread traffic across them in their MPLS networks. LFI should be deployed in the CE-to-PE link for efficiency, where traffic uses lower link bandwidth (less than 768 kbps). The MPLS—Multilink PPP Support feature can reduce the number of IGP adjacencies and facilitate load sharing of traffic.
The tasks in this section can be performed on CE-to-PE links, PE-to-P links, P-to-P links, and CSC CSC-CE-to-CSC-PE links.
Enabling Cisco Express Forwarding or Distributed Cisco Express Forwarding Switching
Perform the following task to enable Cisco Express Forwarding or distributed Cisco Express Forwarding switching. Cisco Express Forwarding or distributed Cisco Express Forwarding is required for the forwarding of MLP or dMLP traffic.
Prerequisites
Multilink PPP requires the configuration of standard Cisco Express Forwarding. Distributed MLP (dMLP) requires the configuration of distributed Cisco Express Forwarding.
Cisco Express Forwarding is enabled by default on most Cisco platforms running Cisco IOS software Release12.0 or a later release. To find out if Cisco Express Forwarding is enabled on your platform, enter the show ip cef command. If Cisco Express Forwarding is enabled, you receive output that looks like this:
Router# show ip cefPrefix Next Hop Interface10.2.61.8/24 192.168.100.1 FastEthernet1/0/0192.168.101.1 FastEthernet6/1If Cisco Express Forwarding is not enabled on your platform, the output for the show ip cef command looks like this:
Router# show ip cef%CEF not runningDistributed Cisco Express Forwarding is enabled by default on devices such as the Catalyst 6500 series switch, the Cisco 7500 series router, and the Cisco 12000 series Internet router.
SUMMARY STEPS
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ip cef distributed4.
DETAILED STEPS
Creating a Multilink Bundle for MPLS—Multilink PPP Support
Perform this task to create a multilink bundle for the MPLS—Multilink PPP Support feature. This can reduce the number of IGP adjacencies and facilitate load sharing of traffic.
SUMMARY STEPS
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DETAILED STEPS
Assigning an Interface to a Multilink Bundle for MPLS—Multilink PPP Support
Perform this task to assign an interface to a multilink bundle for the MPLS—Multilink PPP Support feature.
SUMMARY STEPS
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DETAILED STEPS
Disabling PPP Multilink Fragmentation
Perform this task to disable PPP multilink fragmentation. PPP multilink fragmentation is enabled by default.
Enabling fragmentation reduces the delay latency among bundle links, but adds some load to the CPU. Disabling fragmentation might produce better throughput.
If your data traffic is consistently of a similar size, we recommend disabling fragmentation. In this case, the benefits of fragmentation can be outweighed by the added load on the CPU.
Distributed MLP over MPLS does not support fragmentation of the packets, unless you enable LFI on the MLP interface using the following commands:
Router(config)# interface multilink group-numberRouter(config-if)# ppp multilink interleaveRouter(config-if)# ppp multilink fragment-delay millisecondsSUMMARY STEPS
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DETAILED STEPS
Verifying the Multilink PPP Configuration
Perform the following task to verify the Multilink PPP configuration.
SUMMARY STEPS
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DETAILED STEPS
Step 1
Use this command to enable privileged EXEC mode. Enter your password if prompted. For example:
Router> enableRouter#Step 2
Use this command to verify logical and physical MLP interfaces. For example:
Router# show ip interface briefLocolrface IP-Address OK? Method Status ProtEthernet0/0/0 10.3.62.106 YES NVRAM up upEthernet0/0/1 unassigned YES NVRAM administratively down downEthernet0/0/2 unassigned YES NVRAM administratively down downEthernet0/0/3 unassigned YES NVRAM administratively down downEthernet0/0/4 unassigned YES NVRAM administratively down downEthernet0/0/5 unassigned YES NVRAM administratively down downEthernet0/0/6 unassigned YES NVRAM administratively down downEthernet0/0/7 unassigned YES NVRAM administratively down downEthernet0/1/0 unassigned YES NVRAM administratively down downEthernet0/1/1 unassigned YES NVRAM administratively down downEthernet0/1/2 unassigned YES NVRAM administratively down downEthernet0/1/3 unassigned YES NVRAM administratively down downEthernet0/1/4 unassigned YES NVRAM administratively down downEthernet0/1/5 unassigned YES NVRAM administratively down downEthernet0/1/6 unassigned YES NVRAM administratively down downEthernet0/1/7 unassigned YES NVRAM administratively down downSerial1/1/0:1 unassigned YES NVRAM administratively down downSerial1/1/0:2 unassigned YES NVRAM administratively down downSerial1/1/1:1 unassigned YES NVRAM up upSerial1/1/1:2 unassigned YES NVRAM up downSerial1/1/3:1 unassigned YES NVRAM up upSerial1/1/3:2 unassigned YES NVRAM up upMultilink6 10.30.0.2 YES NVRAM up upMultilink8 unassigned YES NVRAM administratively down downMultilink10 10.34.0.2 YES NVRAM up upLoopback0 10.0.0.1 YES NVRAM up upStep 3
Use this command to verify that you have created a multilink bundle. For example:
Router# show ppp multilinkMultilink1, bundle name is group 1Bundle is Distributed0 lost fragments, 0 reordered, 0 unassigned, sequence 0x0/0x0 rcvd/sent0 discarded, 0 lost received, 1/255 loadMember links: 4 active, 0 inactive (max no set, min not set)Serial1/0/0/:1Serial1/0/0/:2Serial1/0/0/:3Serial1/0/0/:4Step 4
Use this command to display information about a specific MLP interface. For example:
Router# show ppp multilink interface multilink6Multilink6, bundle name is routerBundle up for 00:42:46, 1/255 loadReceive buffer limit 24384 bytes, frag timeout 1524 msBundle is Distributed0/0 fragments/bytes in reassembly list1 lost fragments, 48 reordered0/0 discarded fragments/bytes, 0 lost received0x4D7 received sequence, 0x0 sent sequenceMember links: 2 active, 0 inactive (max not set, min not set)Se1/1/3:1, since 00:42:46, 240 weight, 232 frag sizeSe1/1/3:2, since 00:42:46, 240 weight, 232 frag sizedLFI statistics:DLFI Packets Pkts In Chars In Pkts Out Chars OutFragmented 86 13072 86 12857UnFragmented 1144 85502 1091 82208Reassembled 1187 98230 1134 94721Reassembly Drops 0Fragmentation Drops 0Out of Seq Frags 1
Note
Step 5
Use this command to display information about serial interfaces in your configuration. For example:
Router# show interface serial 1/1/3:1Serial1/1/3:1 is up, line protocol is upHardware is Multichannel T1MTU 1500 bytes, BW 64 Kbit, DLY 20000 usec,reliability 255/255, txload 1/255, rxload 1/255Encapsulation PPP, LCP Open, multilink Open, crc 16, Data non-invertedLast input 00:00:01, output 00:00:01, output hang neverLast clearing of "show interface" counters 00:47:13Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0Queueing strategy: fifoOutput queue: 0/40 (size/max)5 minute input rate 0 bits/sec, 0 packets/sec5 minute output rate 0 bits/sec, 0 packets/sec722 packets input, 54323 bytes, 0 no bufferReceived 0 broadcasts, 0 runts, 0 giants, 0 throttles0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort697 packets output, 51888 bytes, 0 underruns0 output errors, 0 collisions, 1 interface resets0 output buffer failures, 0 output buffers swapped out1 carrier transitions no alarm presentTimeslot(s) Used:1, subrate: 64Kb/s, transmit delay is 0 flagsTransmit queue length 25Router# show interface serial 1/1/3:2Serial1/1/3:2 is up, line protocol is upHardware is Multichannel T1MTU 1500 bytes, BW 64 Kbit, DLY 20000 usec,reliability 255/255, txload 1/255, rxload 1/255Encapsulation PPP, LCP Open, multilink Open, crc 16, Data non-invertedLast input 00:00:03, output 00:00:03, output hang neverLast clearing of "show interface" counters 00:47:16Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0Queueing strategy: fifoOutput queue: 0/40 (size/max)5 minute input rate 0 bits/sec, 0 packets/sec5 minute output rate 0 bits/sec, 0 packets/sec725 packets input, 54618 bytes, 0 no bufferReceived 0 broadcasts, 0 runts, 0 giants, 0 throttles0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort693 packets output, 53180 bytes, 0 underruns0 output errors, 0 collisions, 1 interface resets0 output buffer failures, 0 output buffers swapped out1 carrier transitions no alarm presentTimeslot(s) Used:2, subrate: 64Kb/s, transmit delay is 0 flagsTransmit queue length 26You can also use the show interface command to display information about the multilink interface:
Router# show interface multilink6Multilink6 is up, line protocol is upHardware is multilink group interfaceInternet address is 10.30.0.2/8MTU 1500 bytes, BW 128 Kbit, DLY 100000 usec,reliability 255/255, txload 1/255, rxload 1/255Encapsulation PPP, LCP Open, multilink OpenOpen: CDPCP, IPCP, TAGCP, loopback not setDTR is pulsed for 2 seconds on resetLast input 00:00:00, output never, output hang neverLast clearing of "show interface" counters 00:48:43Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0Queueing strategy: fifoOutput queue: 0/40 (size/max)30 second input rate 0 bits/sec, 0 packets/sec30 second output rate 0 bits/sec, 0 packets/sec1340 packets input, 102245 bytes, 0 no bufferReceived 0 broadcasts, 0 runts, 0 giants, 0 throttles0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort1283 packets output, 101350 bytes, 0 underruns0 output errors, 0 collisions, 1 interface resets0 output buffer failures, 0 output buffers swapped out0 carrier transitionsStep 6
Use this command to display contents of the MPLS Label Forwarding Information Base (LFIB) and look for information on multilink interfaces associated with a point2point next hop. For example:
Router# show mpls forwarding-tableLocal Outgoing Prefix Bytes tag Outgoing Next Hoptag tag or VC or Tunnel Id switched interface16 Untagged 10.30.0.1/32 0 Mu6 point2point17 Pop tag 10.0.0.3/32 0 Mu6 point2point18 Untagged 10.0.0.9/32[V] 0 Mu10 point2point19 Untagged 10.0.0.11/32[V] 6890 Mu10 point2point20 Untagged 10.32.0.0/8[V] 530 Mu10 point2point21 Aggregate 10.34.0.0/8[V] 022 Untagged 10.34.0.1/32[V] 0 Mu10 point2pointUse the show ip bgp vpnv4 command to display VPN address information from the Border Gateway Protocol (BGP) table:
Router# show ip bgp vpnv4 all summaryBGP router identifier 10.0.0.1, local AS number 100BGP table version is 21, main routing table version 2110 network entries using 1210 bytes of memory10 path entries using 640 bytes of memory2 BGP path attribute entries using 120 bytes of memory1 BGP extended community entries using 24 bytes of memory0 BGP route-map cache entries using 0 bytes of memory0 BGP filter-list cache entries using 0 bytes of memoryBGP using 1994 total bytes of memoryBGP activity 10/0 prefixes, 10/0 paths, scan interval 5 secs10.0.0.3 4 100 MsgRc52 MsgSe52 TblV21 0 0 00:46:35 State/P5xRcdStep 7
Use this command to exit to user EXEC mode. For example:
Router# exitRouter>
Configuration Examples for MPLS—Multilink PPP Support
The following are configuration examples for the MPLS—Multilink PPP Support feature:
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Sample MPLS—Multilink PPP Support Configurations
The following examples show sample configurations for MLP on a Cisco 7200 router, on a Cisco 7500 router, and on a CSC network. The configuration of MLP on an interface is the same for PE-to-CE links, PE-to-P links, and P-to-P links.
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Sample Multilink PPP Configuration on a Cisco 7200 Series Router
Following is a sample configuration of a Cisco 7200 router, which is connected with a T1 line card and configured with an MPLS Multilink PPP interface:
controller T1 1/3framing esfclock source internallinecode b8zschannel-group 1 timeslots 1channel-group 2 timeslots 2no yellow generationno yellow detection!interface Multilink6ip address 10.37.0.1 255.0.0.0ppp multilink interleavetag-switching ipload-interval 30multilink-group 6!interface Serial1/3:1encapsulation pppno ip addressppp multilinktx-queue-limit 26multilink-group 6peer neighbor-route!interface Serial1/3:2encapsulation pppno ip addressppp multilinktx-queue-limit 26multilink-group 6peer neighbor-routeSample Multilink PPP Configuration for a Cisco 7500 Series Router
Following is a sample configuration of a Cisco 7500 router, which is connected with a T1 line card and configured with an MPLS Multilink PPP interface:
controller T1 1/1/3framing esfclock source internallinecode b8zschannel-group 1 timeslots 1channel-group 2 timeslots 2no yellow generationno yellow detection!interface Multilink6ip address 10.37.0.2 255.0.0.0ppp multilink interleavetag-switching ipload-interval 30multilink-group 6!interface Serial1/1/3:1encapsulation pppno ip addressppp multilinktx-queue-limit 26multilink-group 6peer neighbor-route!interface Serial1/1/3:2encapsulation pppno ip addressppp multilinktx-queue-limit 26multilink-group 6peer neighbor-routeSample Multilink PPP Configuration on an MPLS CSC PE Router
Following is a sample configuration for an MPLS CSC PE router. An eBGP session is configured between the PE and CE routers.
PE-Router# show running-config interface Serial1/0:1Building configuration...!mpls label protocol ldpip cefip vrf vpn2rd 200:1route-target export 200:1route-target import 200:1!controller T1 1/0framing esfclock source internallinecode b8zschannel-group 1 timeslots 1channel-group 2 timeslots 2no yellow generationno yellow detection!interface Serial1/0:1no ip addressencapsulation ppptx-ring-limit 26ppp multilinkppp multilink group 1!interface Serial1/0:2no ip addressencapsulation ppptx-ring-limit 26ppp multilinkppp multilink group 1!interface Multilink1ip vrf forwarding vpn2ip address 10.35.0.2 255.0.0.0no peer neighbor-routeload-interval 30ppp multilinkppp multilink interleaveppp multilink group 1!!router ospf 200log-adjacency-changesauto-cost reference-bandwidth 1000redistribute connected subnetspassive-interface Multilink1network 10.0.0.7 0.0.0.0 area 200network 10.31.0.0 0.255.255.255 area 200!!router bgp 200no bgp default ipv4-unicastbgp log-neighbor-changesneighbor 10.0.0.11 remote-as 200neighbor 10.0.0.11 update-source Loopback0!address-family vpnv4neighbor 10.0.0.11 activateneighbor 10.0.0.11 send-community extendedbgp scan-time import 5exit-address-family!address-family ipv4 vrf vpn2redistribute connectedneighbor 10.35.0.1 remote-as 300neighbor 10.35.0.1 activateneighbor 10.35.0.1 as-overrideneighbor 10.35.0.1 advertisement-interval 5no auto-summaryno synchronizationexit-address-familyEnabling Cisco Express Forwarding or Distributed Cisco Express Forwarding: Example
The following example shows how to enable Cisco Express Forwarding for MLP configurations:
enableconfigure terminalip cefThe following example shows how to enable distributed Cisco Express Forwarding for dMLP configurations:
enableconfigure terminalip cef distributedCreating a Multilink Bundle for MPLS—Multilink PPP Support: Example
The following example shows how to create a multilink bundle for the MPLS—Multilink PPP Support feature:
interface multilink 1ip address 10.0.0.0 10.255.255.255encapsulation pppppp chap hostname group 1ppp multilinkmultilink-group 1Assigning an Interface to a Multilink Bundle for MPLS—Multilink PPP Support: Example
The following example shows how to create four multilink interfaces with distributed Cisco Express Forwarding switching and MLP enabled. Each of the newly created interfaces is added to a multilink bundle for the MPLS—Multilink PPP Support feature.
interface multilink 1ip address 10.0.0.0 10.255.255.255ppp chap hostname group 1ppp multilinkmultilink-group 1interface serial 1/0/0/:1no ip addressencapsulation pppip route-cache distributedno keepaliveppp multilinkmultilink-group 1interface serial 1/0/0/:2no ip addressencapsulation pppip route-cache distributedno keepaliveppp chap hostname group 1ppp multilinkmultilink-group 1interface serial 1/0/0/:3no ip addressencapsulation pppip route-cache distributedno keepaliveppp chap hostname group 1ppp multilinkmultilink-group 1interface serial 1/0/0/:4no ip addressencapsulation pppip route-cache distributedno keepaliveppp chap hostname group 1ppp multilinkmultilink-groupAdditional References
The following sections provide references related to the MPLS—Multilink PPP Support feature:
Related Documents
Configuration tasks for distributed MLP for Cisco 7500 series routers
Distributed Multilink Point-to-Point Protocol for Cisco 7500 Series Routers
Configuration tasks for media-independent PPP and Multilink PPP
Configuration tasks for MPLS DiffServ tunneling modes
Configuration tasks for the MPLS QoS multi-VC mode feature
Configuring MPLS" chapter, Cisco IOS Multiprotocol Label Switching Configuration Guide
Configuration tasks for MPLS VPNs
"MPLS Virtual Private Networks" chapter, Cisco IOS Multiprotocol Label Switching Configuration Guide
Configuration tasks for MPLS VPN CSC
"MPLS Virtual Private Networks" chapter, Cisco IOS Multiprotocol Label Switching Configuration Guide
Configuration tasks for MPLS VPN CSC with IPv4 BGP label distribution
"MPLS Virtual Private Networks" chapter, Cisco IOS Multiprotocol Label Switching Configuration Guide
Configuration tasks for MPLS VPN Inter-AS with IPv4 BGP label distribution
"MPLS Virtual Private Networks" chapter, Cisco IOS Multiprotocol Label Switching Configuration Guide
Standards
No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature.
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MIBs
RFCs
Technical Assistance
Command Reference
This feature uses no new or modified commands.
Feature Information for MPLS—Multilink PPP Support
Table 5 lists the release history for this feature.
Not all commands may be available in your Cisco IOS software release. For release information about a specific command, see the command reference documentation.
Cisco IOS software images are specific to a Cisco IOS software release, a feature set, and a platform. Use Cisco Feature Navigator to find information about platform support and Cisco IOS software image support. Access Cisco Feature Navigator at http://www.cisco.com/go/fn. You must have an account on Cisco.com. If you do not have an account or have forgotten your username or password, click Cancel at the login dialog box and follow the instructions that appear.
Note
Table 5 Feature Information for MPLS—Multilink PPP Support
MPLS—Multilink PPP Support
12.2(8)T
12.2(15)T1012.3(5a)
12.3(7)T
12.2(28)SB
12.4(20)TThe MPLS—Multilink PPP Support feature ensures that MPLS Layer 3 Virtual Private Networks (VPNs) with quality of service (QoS) can be enabled for bundled links. This feature supports Multiprotocol Label Switching (MPLS) over Multilink PPP (MLP) links in the edge (provider edge [PE]-to-customer edge [CE]) or in the MPLS core (PE-to-PE and PE-to-provider router [P]).
Service providers that use relatively low-speed links can use MLP to spread traffic across them in their MPLS networks. Link fragmentation and interleaving (LFI) should be deployed in the CE-to-PE link for efficiency, where traffic uses a lower link bandwidth (less than 768 kbps).
In 12.2(8)T, MLP support on CE-to-PE links was introduced.
In 12.2(15)T10 and 12.3(5a), MLP support for MPLS networks was extended to PE-to-P links, PE-to-PE links, Carrier Supporting Carrier (CSC) CSC-CE-to-CSC-PE links, and interautonomous system (Inter-AS) PE-to-PE links.
In 12.3(7)T, the feature was integrated into the Cisco IOS 12.3T release.
In 12.2(28)SB, the feature was integrated into the Cisco IOS 12.2SB release.
In 12.4(20)T, the feature was integrated into the Cisco IOS 12.4T release.
The following sections provide information about this feature:
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Glossary
bundle—A group of interfaces connected by parallel links between two systems that have agreed to use Multilink PPP (MLP) over those links.
CBWFQ—class-based weighted fair queueing. A queueing option that extends the standard Weighted Fair Queueing (WFQ) functionality to provide support for user-defined traffic classes.
Cisco Express Forwarding—A proprietary form of switching that optimizes network performance and scalability for networks with large and dynamic traffic patterns, such as the Internet, and for networks characterized by intensive web-based applications or interactive sessions. Although you can use Cisco Express Forwarding in any part of a network, it is designed for high-performance, highly resilient Layer 3 IP backbone switching.
EIGRP—Enhanced Interior Gateway Routing Protocol. An advanced version of the Interior Gateway Routing Protocol (IGRP) developed by Cisco. It provides superior convergence properties and operating efficiency, and combines the advantages of link-state protocols with those of distance vector protocols.
IGP—Interior Gateway Protocol. An Internet protocol used to exchange routing information within an autonomous system. Examples of common Internet IGPs include Interior Gateway Routing Protocol (IGRP), Open Shortest Path First (OSPF), and Routing Information Protocol (RIP).
IGRP—Interior Gateway Routing Protocol. An Interior Gateway Protocol (IGP) developed by Cisco to address the issues associated with routing in large, heterogeneous networks. Compare with Enhanced Interior Gateway Routing Protocol (EIGRP).
IS-IS—Intermediate System-to-Intermediate System. An Open Systems Interconnection (OSI) link-state hierarchical routing protocol, based on DECnet Phase V routing, in which IS-IS routers exchange routing information based on a single metric to determine network topology.
LCP—Link Control Protocol. A protocol that establishes, configures, and tests data link connections for use by PPP.
LFI—link fragmentation and interleaving. The Cisco IOS LFI feature reduces delay on slower-speed links by breaking up large datagrams and interleaving low-delay traffic packets with the smaller packets resulting from the fragmented datagram. LFI allows reserve queues to be set up so that Real-Time Protocol (RTP) streams can be mapped into a higher priority queue in the configured weighted fair queue set.
link—One of the interfaces in a bundle.
LLQ—low latency queueing. A quality of service QoS queueing feature that provides a strict priority queue (PQ) for voice traffic and weighted fair queues for other classes of traffic. It is also called priority queueing/class-based weighted fair queueing (PQ/CBWFQ).
MLP—Multilink PPP. A method of splitting, recombining, and sequencing datagrams across multiple logical links. The use of MLP increases throughput between two sites by grouping interfaces and then load balancing packets over the grouped interfaces (called a bundle). Splitting packets at one end, sending them over the bundled interfaces, and recombining them at the other end achieves load balancing.
MQC—Modular QoS CLI. MQC is a CLI structure that allows users to create traffic polices and attach these polices to interfaces. MQC allows users to specify a traffic class independently of QoS policies.
NCP—Network Control Protocol. A series of protocols for establishing and configuring different network layer protocols (such as for AppleTalk) over PPP.
OSPF—Open Shortest Path First. A link-state, hierarchical Interior Gateway Protocol (IGP) routing algorithm proposed as a successor to Routing Information Protocol (RIP) in the Internet community. OSPF features include least-cost routing, multipath routing, and load balancing. OSPF was derived from an early version of the IS-IS protocol.
PPP—Point-to-Point Protocol. A successor to the Serial Line Interface Protocol (SLIP) that provides router-to-router and host-to-network connections over synchronous and asynchronous circuits. PPP works with several network layer protocols (such as IP, Internetwork Packet Exchange [IPX], and AppleTalk Remote Access [ARA]). PPP also has built-in security mechanisms (such as Challenge Handshake Authentication Protocol [CHAP] and Password Authentication Protocol [PAP]). PPP relies on two protocols: Link Control Protocol (LCP) and Network Control Protocol (NCP).
RIP—Routing Information Protocol. A version of Interior Gateway Protocol (IGP) that is supplied with UNIX Berkeley Standard Distribution (BSD) systems. Routing Information Protocol (RIP) is the most common IGP in the Internet. It uses hop count as a routing metric.
RSP—Route Switch Processor. A processor module used in the Cisco 7500 series routers that integrates the functions of the Route Processor and the Switch Processor. The former contains the CPU, system software, and most of the router's memory components; the latter is a processor module that acts as the administrator for all Cisco Extended Bus activities.
VIP—Versatile Interface Processor. An interface card that is used in Cisco 7000 and Cisco 7500 series routers. It can hold different port adapters for interfaces to various media (Ethernet, Token Ring, FDDI, ATM, and so on). The VIP supports two port adapters, standard packet delivery, distributed Cisco Express Forwarding, and feature off-load.
Virtual Bundle Interface—An interface that represents the master link of a bundle. It is not tied to any physical interface. Data going over the bundle is transmitted and received through the master link.
WFQ—weighted fair queueing. A congestion management algorithm that identifies conversations (in the form of traffic streams), separates packets that belong to each conversation, and ensures that capacity is shared fairly among the individual conversations. WFQ is an automatic way of stabilizing network behavior during congestion and results in improved performance and reduced retransmission.
WRED—weighted random early detection. A queueing method that ensures that high-precedence traffic has lower loss rates than other traffic during times of congestion.
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