MPLS�Multilink PPP Support

Table Of Contents

MPLS—Multilink PPP Support

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 CEF or Distributed CEF Switching

Prerequisites

Creating a Multilink Bundle

Assigning an Interface to a Multilink Bundle

Troubleshooting Tips

Disabling PPP Multilink Fragmentation

Verifying the Multilink PPP Configuration

Examples

Configuration Examples for MPLS—Multilink PPP Support

Sample MPLS—Multilink PPP Support Configurations

Sample Multilink PPP Configuration on Cisco 7200 Series Router

Sample Multilink PPP Configuration for Cisco 7500 Series Router

Sample Multilink PPP Configuration on an MPLS CSC PE Router

Enabling CEF or Distributed CEF: Example

Creating a Multilink Bundle: Example

Assigning an Interface to a Multilink Bundle: Example

Additional References

Related Documents

Standards

MIBs

RFCs

Technical Assistance

Glossary

MPLS—Multilink PPP Support

The Multiprotocol Label Switching (MPLS)—Multilink Point-to-Point Protocol (MLPPP) 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 MPLS over MLPPP 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 MLPPP to spread traffic across multiple low-speed links in their MPLS networks. Link Fragmentation and Interleaving (LFI) should be deployed in the CE-to-PE link for efficiency, where you use smaller link bandwidths (less than 768 kbps).

Feature History for MPLS—Multilink PPP Support

Release

Modification

12.2(8)T

MLPPP support on CE-to-PE links was introduced.

12.2(15)T10, 12.3(5a)

MLPPP support for MPLS networks was extended to PE-to-P links, PE-to-PE links, Carrier Supporting Carrier (CSC) CE-to-PE links, and interautonomous system (Inter-AS) PE-to-PE links.

Finding Support Information for Platforms and Cisco IOS Software Images

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.

Contents

•Prerequisites for MPLS—Multilink PPP Support

•Restrictions for MPLS—Multilink PPP Support

•Information About MPLS—Multilink PPP Support

•How to Configure MPLS—Multilink PPP Support

•Configuration Examples for MPLS—Multilink PPP Support

•Additional References

•Glossary

Prerequisites for MPLS—Multilink PPP Support

MPLS—Multilink PPP Support requires the following:

•Cisco Express Forwarding (CEF) or distributed CEF (dCEF) enabled

•MPLS enabled on PE and P routers

•CEF switching enabled on the interface with the ip route-cache cef command

Table 1 lists the required port adapters and processors for MPLS—Multilink PPP Support on the Cisco 7200 series routers. Table 2 lists the required port adapters and processors for MPLS—Multilink PPP Support on the Cisco 7500 series routers.

Table 1 Required Cisco 7200 Port Adapters and Processors for MPLS—Multilink PPP Support

Port Adapter

Processor

PA-4T+

PA-8T

Channelized adapters

•PA-MC-2E1/120

•PA-MC-2T1

•PA-MC-2T3+

•PA-MC-4T1

•PA-MC-8E1/120

•PA-MC-8T1

•PA-MC-E3

•PA-MC-STM-1MM

•PA-MC-STM-1SMI

•PA-MC-T3

•PA-MC-8TE1+

Network processing engine models

•NPE-400

•NPE-G1

•NSE-1

Table 2 Required Cisco 7500 Port Adapters and Processors for MPLS—Multilink PPP Support

Port Adapter

Processor

PA-4T+

PA-8T

Channelized adapters

•PA-MC-2E1/120

•PA-MC-2T1

•PA-MC-2T3+

•PA-MC-4T1

•PA-MC-8E1/120

•PA-MC-8T1

•PA-MC-E3

•PA-MC-STM-1MM

•PA-MC-STM-1SMI

•PA-MC-T3

•PA-MC-8TE1+

Route Switch Processors

•RSP16

•RSP8

•RSP4+

Versatile interface processors

•VIP4-50, VIP4-80

•VIP6-80

Restrictions for MPLS—Multilink PPP Support

The MPLS—Multilink PPP Support feature has no restrictions, except for platform-specific restrictions that apply to the use of MLPPP and Distributed MLPPP (dMLPPP).

For restrictions that apply to dMLPPP 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:

•MPLS 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

MPLS Features Supported for Multilink PPP

The following topics provide information about MPLS features supported for MLPPP:

•MPLS Layer 3 Virtual Private Network Features Supported for Multilink PPP

•MPLS Quality of Service Features Supported for Multilink PPP

MPLS Layer 3 Virtual Private Network Features Supported for Multilink PPP

Table 3 lists MPLS Layer 3 VPN features supported for MLPPP 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 MLPPP

MPLS L3 VPN Feature

CE-to-PE Links

PE-to-P Links

CSC CE-to-PE Links

Static routes

Supported

—¹

—

External Border Gateway Protocol (EBGP)

Supported

Not applicable to this configuration

Supported

Intermediate System-to-Intermediate System (IS-IS)

—

Supported

—

Open Shortest Path first (OSPF)

Supported

Supported

—

Enhanced Interior Gateway Routing Protocol (EIGRP)

Supported

Supported

—

Interprovider (InterAS) VPNs (with LDP)

Not applicable to this configuration

Supported (MLPPP between ASBRs)

Not applicable to this configuration

InterAS VPNs with IPv4 Label Distribution

Not applicable to this configuration

Supported (MLPPP between autonomous system border routers [ASBRs])

Not applicable to this configuration

CSC VPNs (with LDP)

—

Not applicable to this configuration

Supported

CSC VPNs with IPv4 label distribution

Supported

Not applicable to this configuration

Supported

eiBGP Multipath

—

—

Not applicable to this configuration

iBGP Multipath

Not applicable to this configuration

—

Not applicable to this configuration

eBGP Multipath

—

—

—

¹An em dash (—) indicates that the configuration is not supported in this release.

MPLS Quality of Service Features Supported for Multilink PPP

Table 4 lists the MPLS quality of service (QoS) features supported for MLPPP 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 4 MPLS QoS Features Supported for MLPPP

MPLS QoS Feature

CE-to-PE Links

PE-to-P Links

CSC CE-to-PE Links

Default copy of IP Precedence to EXP bits and the reverse

Supported

—¹

—

Set MPLS EXP bits using modular QoS CLI (MQC)

Supported

Supported

Supported

Matching on MPLS EXP using MQC

Supported

Supported

Supported

LLQ/CBWFQ support

Supported

Supported

Supported

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

¹An em dash (—) indicates that the configuration is not supported in this release.

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, MLPPP is deployed on the PE-to-CE links. The VPN routing/forwarding instance (VRF) interface is in a multilink bundle. There is no MPLS interaction with MLPPP; all packets coming into the MLPPP bundle are IP packets.

Figure 1 MLPPP and Traditional PE-to-CE Links

The PE-to-CE routing protocols that are supported for the MPLS—Multilink PPP Support feature include 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 include Link Fragmentation and Interleaving (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 MLPPP on PE-to-P and P-to-P links. Enabling MPLS on MLPPP for PE-to-P links is similar to enabling MPLS on MLPPP for P-to-P links.

Figure 2 MLPPP on PE-to-P Core Links

You employ MLPPP 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 MLPPP on the PE-to-P links, the MPLS—Multilink PPP Support feature requires the configuration of an IGP routing protocol and Label Distribution Protocol (LDP).

MPLS—Multilink PPP Support in a CSC Network

Figure 3 shows a typical MPLS VPN CSC network where MLPPP is configured on the CSC-CE-to-CSC-PE links.

Figure 3 MLPPP on CSC-CE-to-CSC-PE Links with MPLS VPN Carrier Supporting Carrier

The MPLS—Multilink PPP Support feature supports MLPPP 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 MLPPP links that this feature supports for CSC configurations.

Figure 4 MLPPP 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 MLPPP is configured on the PE-to-CE links.

Figure 5 MLPPP on ASBR-to-PE Links in an MPLS VPN Inter-AS Network

The MPLS—Multilink PPP Support feature supports MLPPP 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:

•Enabling CEF or Distributed CEF Switching (required)

•Creating a Multilink Bundle (required)

•Assigning an Interface to a Multilink Bundle (required)

•Disabling PPP Multilink Fragmentation (optional)

•Verifying the Multilink PPP Configuration (optional)

Enabling CEF or Distributed CEF Switching

Perform the following task to enable CEF or distributed CEF (dCEF) switching.

Prerequisites

Multilink PPP requires the configuration of standard CEF. Distributed MLPPP (dMLPPP) requires the configuration of dCEF.

SUMMARY STEPS

1. enable

2. configure terminal

3. ip cef or ip cef distributed

4. exit

DETAILED STEPS

Command or Action

Purpose

Step 1

enable
Example:

Router> enable

Enables privileged EXEC mode.

•Enter your password if prompted.

Step 2

configure terminal
Example:

Router# configure terminal

Enters global configuration mode.

Step 3

ip cef
or

ip cef distributed
Example:

Router(config)# ip cef
or

Router(config)# ip cef distributed

Enables standard CEF switching.

or

Enables distributed CEF switching.

Step 4

exit
Example:

Router(config)# exit

Exits to privileged EXEC mode.

Creating a Multilink Bundle

Perform this task to create a multilink bundle.

SUMMARY STEPS

1. enable

2. configure terminal

3. interface multilink group-number

4. ip address address mask [secondary]

5. encapsulation encapsulation-type

6. ppp multilink

7. end

DETAILED STEPS

Command or Action

Purpose

Step 1

enable
Example:

Router> enable

Enables privileged EXEC mode.

•Enter your password if prompted.

Step 2

configure terminal
Example:

Router# configure terminal

Enters global configuration mode.

Step 3

interface multilink group-number
Example:

Router(config)# interface multilink 1

Creates a multilink bundle or enters multilink interface configuration mode.

•The group-number argument is the number of the multilink bundle (a nonzero number).

Step 4

ip address address mask [secondary]
Example:

Router(config-if)# ip address address mask

Sets a primary or secondary IP address for an interface.

•The address argument is the IP address.

•The mask argument is the mask for the associated IP subnet.

•The secondary keyword specifies that the configured address is a secondary IP address. If this keyword is omitted, the configured address is the primary IP address.

This command is used to assign an IP address to the multilink interface.

Step 5

encapsulation encapsulation-type
Example:

Router(config-if)# encapsulation ppp

Sets the encapsulation method used by the interface.

•The encapsulation-type argument specifies the encapsulation type. The keyword ppp enables PPP encapsulation.

Step 6

ppp multilink
Example:

Router(config-if)# ppp multilink

Enables Multilink PPP (MLPPP) on an interface.

Step 7

end
Example:

Router(config)# end

Exits to privileged EXEC mode.

Assigning an Interface to a Multilink Bundle

Perform this task to assign an interface to a multilink bundle.

SUMMARY STEPS

1. enable

2. configure terminal

3. controller {t1 | e1} slot/port

4. channel-group channel-number timeslots range

5. exit

6. interface slot/port: channel-number

7. ip route-cache cef

8. no ip address

9. keepalive [period [retries]]

10. encapsulation encapsulation-type

11. multilink-group group-number

12. ppp multilink

13. ppp authentication chap

14. end

DETAILED STEPS

Command or Action

Purpose

Step 1

enable
Example:

Router> enable

Enables privileged EXEC mode.

•Enter your password if prompted.

Step 2

configure terminal
Example:

Router# configure terminal

Enters global configuration mode.

Step 3

controller {t1 | e1} slot/port
Example:

Router# controller t1 1/3

Configures a T1 or E1 controller and enters controller configuration mode.

•The t1 keyword indicates a T1 line card.

•The e1 keyword indicates an E1 line card.

•The slot/port arguments are the backplane slot number and port number on the interface. Refer to your hardware installation manual for the specific slot numbers and port numbers.

Step 4

channel-group channel-number timeslots range
Example:

Router(config-controller)# channel-group 1 timeslots 1

Defines the time slots that belong to each T1 or E1 circuit.

•The channel-number argument is the channel-group number. When a T1 data line is configured, channel-group numbers can be values from 0 to 23. When an E1 data line is configured, channel-group numbers can be values from 0 to 30.

•The timeslots range keyword-argument pair specifies one or more time slots or ranges of time slots belonging to the channel group. The first time slot is numbered 1. For a T1 controller, the time slot range is from 1 to 24. For an E1 controller, the time slot range is from 1 to 31. You can specify a time slot range (for example, 1-29), individual time slots separated by commas (for example 1, 3, 5), or a combination of the two (for example 1-14, 15, 17-31).

Step 5

exit
Example:

Router(config-controller)# exit

Exits to global configuration mode.

Step 6

interface slot/port: channel-number
Example:

Router(config)# interface serial 1/0:1

Configures an interface type and enters interface configuration mode.

•The slot argument indicates slot number. Refer to the appropriate hardware manual for slot and port information.

•The /port argument indicates the port number. Refer to the appropriate hardware manual for slot and port information.

•The :channel-number argument indicates the channel group number. Cisco 7500 series routers specify the channel group number in the range of 0 to 4 defined with the channel-group controller configuration command.

Step 7

ip route-cache cef
Example:

Router(confg-if)# ip route-cache cef

Enables CEF operation on an interface after CEF operation was disabled.

Step 8

no ip address
Example:

Router(config-if)# no ip address

Removes any specified IP address.

Step 9

keepalive [period [retries]]
Example:

Router(config-if)# keepalive

Enables keepalive packets and specifies the number of times that the Cisco IOS software tries to send keepalive packets without a response before bringing down the interface or before bringing the tunnel protocol down for a specific interface.

•The period argument is an integer value, in seconds, greater than 0. The default is 10.

•The retries argument specifies the number of times that the device will continue to send keepalive packets without response before bringing the interface down. Enter an integer value greater than 1 and less than 255. If you do not enter a value, the value that was previously set is used; if no value was specified previously, the default of 5 is used.

If you are using this command with a tunnel interface, specifies the number of times that the device will continue to send keepalive packets without response before bringing the tunnel interface protocol down.

Step 10

encapsulation encapsulation-type
Example:

Router(config-if)# encapsulation ppp

Sets the encapsulation method used by the interface.

•The encapsulation-type argument specifies the encapsulation type. The keyword ppp enables PPP encapsulation.

Step 11

multilink-group group-number
Example:

Router(config-if)# multilink-group 1

Designates an interface as part of a multilink leased line bundle.

•The group-number argument is the number of the multilink bundle (a nonzero number).

Step 12

ppp multilink
Example:

Router(config-if)# ppp multilink

Enables MLPPP on an interface.

Step 13

ppp authentication chap
Example:

Router(config-if)# ppp authentication chap

(Optional) Enables Challenge Handshake Authentication Protocol (CHAP) authentication on a serial interface.

Step 14

end
Example:

Router(config)# end

Exits to privileged EXEC mode.

Troubleshooting Tips

You can verify logical and physical MLPPP interfaces by the use of the show ip interface brief command:
Router# show ip interface brief
Locolrface                  IP-Address      OK? Method Status                Prot
Ethernet0/0/0              3.3.62.106      YES NVRAM  up                    up
Ethernet0/0/1              unassigned      YES NVRAM  administratively down down
Ethernet0/0/2              unassigned      YES NVRAM  administratively down down
Ethernet0/0/3              unassigned      YES NVRAM  administratively down down
Ethernet0/0/4              unassigned      YES NVRAM  administratively down down
Ethernet0/0/5              unassigned      YES NVRAM  administratively down down
Ethernet0/0/6              unassigned      YES NVRAM  administratively down down
Ethernet0/0/7              unassigned      YES NVRAM  administratively down down
Ethernet0/1/0              unassigned      YES NVRAM  administratively down down
Ethernet0/1/1              unassigned      YES NVRAM  administratively down down
Ethernet0/1/2              unassigned      YES NVRAM  administratively down down
Ethernet0/1/3              unassigned      YES NVRAM  administratively down down
Ethernet0/1/4              unassigned      YES NVRAM  administratively down down
Ethernet0/1/5              unassigned      YES NVRAM  administratively down down
Ethernet0/1/6              unassigned      YES NVRAM  administratively down down
Ethernet0/1/7              unassigned      YES NVRAM  administratively down down
Serial1/1/0:1              unassigned      YES NVRAM  administratively down down
Serial1/1/0:2              unassigned      YES NVRAM  administratively down down
Serial1/1/1:1              unassigned      YES NVRAM  up                    up
Serial1/1/1:2              unassigned      YES NVRAM  up                    down
Serial1/1/3:1              unassigned      YES NVRAM  up                    up
Serial1/1/3:2              unassigned      YES NVRAM  up                    up
Multilink6                 30.0.0.2        YES NVRAM  up                    up
Multilink8                 unassigned      YES NVRAM  administratively down down
Multilink10                34.0.0.2        YES NVRAM  up                    up
Loopback0                  10.0.0.1        YES NVRAM  up                    up
You can use the show ppp multilink command to display information about a specific MLPPP interface:
Router# show ppp multilink interface multilink 6
Multilink6, bundle name is router
  Bundle up for 00:42:46, 1/255 load
  Receive buffer limit 24384 bytes, frag timeout 1524 ms
  Bundle is Distributed
    0/0 fragments/bytes in reassembly list
    1 lost fragments, 48 reordered
    0/0 discarded fragments/bytes, 0 lost received
    0x4D7 received sequence, 0x0 sent sequence
  Member links: 2 active, 0 inactive (max not set, min not set)
    Se1/1/3:1, since 00:42:46, 240 weight, 232 frag size
    Se1/1/3:2, since 00:42:46, 240 weight, 232 frag size
dLFI statistics:
            DLFI Packets    Pkts In   Chars In   Pkts Out  Chars Out
              Fragmented         86      13072         86      12857
            UnFragmented       1144      85502       1091      82208
             Reassembled       1187      98230       1134      94721
        Reassembly Drops          0
     Fragmentation Drops          0
        Out of Seq Frags          1
Note On Cisco 7500 routers, dLFI statistics are displayed only if LFI is enabled on a distributed MLPPP interface.

You can use the show interface command to display information about serial interfaces in your configuration:
Router# show interface Serial 1/1/3:1
Serial1/1/3:1 is up, line protocol is up
  Hardware is Multichannel T1
  MTU 1500 bytes, BW 64 Kbit, DLY 20000 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation PPP, LCP Open, multilink Open, crc 16, Data non-inverted
  Last input 00:00:01, output 00:00:01, output hang never
  Last clearing of "show interface" counters 00:47:13
  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
  Queueing strategy: fifo
  Output queue: 0/40 (size/max)
  5 minute input rate 0 bits/sec, 0 packets/sec
  5 minute output rate 0 bits/sec, 0 packets/sec
     722 packets input, 54323 bytes, 0 no buffer
     Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
     697 packets output, 51888 bytes, 0 underruns
     0 output errors, 0 collisions, 1 interface resets
     0 output buffer failures, 0 output buffers swapped out
     1 carrier transitions no alarm present
  Timeslot(s) Used:1, subrate: 64Kb/s, transmit delay is 0 flags
  Transmit queue length 25
Router# show interface Serial 1/1/3:2
Serial1/1/3:2 is up, line protocol is up
  Hardware is Multichannel T1
  MTU 1500 bytes, BW 64 Kbit, DLY 20000 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation PPP, LCP Open, multilink Open, crc 16, Data non-inverted
  Last input 00:00:03, output 00:00:03, output hang never
  Last clearing of "show interface" counters 00:47:16
  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
  Queueing strategy: fifo
  Output queue: 0/40 (size/max)
  5 minute input rate 0 bits/sec, 0 packets/sec
  5 minute output rate 0 bits/sec, 0 packets/sec
     725 packets input, 54618 bytes, 0 no buffer
     Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
     693 packets output, 53180 bytes, 0 underruns
     0 output errors, 0 collisions, 1 interface resets
     0 output buffer failures, 0 output buffers swapped out
     1 carrier transitions no alarm present
  Timeslot(s) Used:2, subrate: 64Kb/s, transmit delay is 0 flags
  Transmit queue length 26
You can also use the show interface command to display information about the multilink interface:
Router# show interface multilink 6
Multilink6 is up, line protocol is up
  Hardware is multilink group interface
  Internet address is 30.0.0.2/8
  MTU 1500 bytes, BW 128 Kbit, DLY 100000 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation PPP, LCP Open, multilink Open
  Open: CDPCP, IPCP, TAGCP, loopback not set
  DTR is pulsed for 2 seconds on reset
  Last input 00:00:00, output never, output hang never
  Last clearing of "show interface" counters 00:48:43
  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
  Queueing strategy: fifo
  Output queue: 0/40 (size/max)
  30 second input rate 0 bits/sec, 0 packets/sec
  30 second output rate 0 bits/sec, 0 packets/sec
     1340 packets input, 102245 bytes, 0 no buffer
     Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
     1283 packets output, 101350 bytes, 0 underruns
     0 output errors, 0 collisions, 1 interface resets
     0 output buffer failures, 0 output buffers swapped out
     0 carrier transitions
Use the show mpls forwarding-table command to view contents of the MPLS label forwarding information base (LFIB):
Router# show mpls forwarding-table
Local  Outgoing    Prefix            Bytes tag  Outgoing   Next Hop
tag    tag or VC   or Tunnel Id      switched   interface
16     Untagged    30.0.0.1/32       0          Mu6        point2point
17     Pop tag     10.0.0.3/32       0          Mu6        point2point
18     Untagged    10.0.0.9/32[V]    0          Mu10       point2point
19     Untagged    10.0.0.11/32[V]   6890       Mu10       point2point
20     Untagged    32.0.0.0/8[V]     530        Mu10       point2point
21     Aggregate   34.0.0.0/8[V]     0
22     Untagged    34.0.0.1/32[V]    0          Mu10       point2point
Use the show ip bgp vpnv4 command to display VPN address information from the Border Gateway Protocol (BGP) table:
Router# show ip bgp vpnv4 all summary
BGP router identifier 10.0.0.1, local AS number 100
BGP table version is 21, main routing table version 21
10 network entries using 1210 bytes of memory
10 path entries using 640 bytes of memory
2 BGP path attribute entries using 120 bytes of memory
1 BGP extended community entries using 24 bytes of memory
0 BGP route-map cache entries using 0 bytes of memory
0 BGP filter-list cache entries using 0 bytes of memory
BGP using 1994 total bytes of memory
BGP activity 10/0 prefixes, 10/0 paths, scan interval 5 secs
10.0.0.3        4   100 MsgRc52 MsgSe52   TblV21    0    0 00:46:35 State/P5xRcd
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 MLPPP over MPLS does not support fragmentation of the packets, unless you enable LFI on the MLPPP interface using the following commands:
Router(config)# interface multilink group-number
Router(config-if)# ppp multilink interleave
Router(config-if)# ppp multilink fragment-delay delay in msec
SUMMARY STEPS

1. enable

2. configure terminal

3. interface type number

4. ppp multilink fragmentation disable

5. end

DETAILED STEPS

Command or Action

Purpose

Step 1

enable
Example:

Router> enable

Enables privileged EXEC mode.

•Enter your password if prompted.

Step 2

configure terminal
Example:

Router# configure terminal

Enters global configuration mode.

Step 3

interface type number
Example:

Router(config)# interface serial 1/0

Configures an interface type and enters interface configuration mode.

•The type argument indicates the type of interface to be configured.

•The number argument specifies the port, connector, or interface card number. The numbers are assigned at the factory at the time of installation or when the interface is added to a system, and can be displayed with the show interfaces command.

Step 4

ppp multilink fragmentation disable
Example:

Router(config-if)# ppp multilink fragmentation disable

Disables packet fragmentation.

Step 5

end
Example:

Router(config)# end

Exits to privileged EXEC mode.

Verifying the Multilink PPP Configuration

Perform the following task to verify the Multilink PPP configuration.

SUMMARY STEPS

1. enable

2. show ppp multilink

3. disable

DETAILED STEPS

Command or Action

Purpose

Step 1

enable
Example:

Router> enable

Enables privileged EXEC mode.

•Enter your password if prompted.

Step 2

show ppp multilink
Example:

Router# show ppp multilink

Displays information about Multilink PPP.

Step 3

disable
Example:

Router# disable

Exits to user EXEC mode.

Examples

The following example shows sample output from a show ppp multilink command:
Router# show ppp multilink
Multilink1, bundle name is group 1
 Bundle is Distributed
0 lost fragments, 0 reordered, 0 unassigned, sequence 0x0/0x0 rcvd/sent
0 discarded, 0 lost received, 1/255 load
Member links: 4 active, 0 inactive (max no set, min not set)
 Serial1/0/0/:1
 Serial1/0/0/:2
 Serial1/0/0/:3
 Serial1/0/0/:4
Configuration Examples for MPLS—Multilink PPP Support

The following are configuration examples for the MPLS—Multilink PPP Support feature:

•Sample MPLS—Multilink PPP Support Configurations

•Enabling CEF or Distributed CEF: Example

•Creating a Multilink Bundle: Example

•Assigning an Interface to a Multilink Bundle: Example

Sample MPLS—Multilink PPP Support Configurations

The following examples show sample configurations for MLPPP on a Cisco 7200 router, a Cisco 7500 router, and on a CSC network. The configuration of MLPPP on an interface is the same for PE-to-CE links, PE-to-P links, and P-to-P links.

•Sample Multilink PPP Configuration on Cisco 7200 Series Router

•Sample Multilink PPP Configuration for Cisco 7500 Series Router

•Sample Multilink PPP Configuration on an MPLS CSC PE Router

Sample Multilink PPP Configuration on 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 1/3
 framing esf
 clock source internal
 linecode b8zs
 channel-group 1 timeslots 1
 channel-group 2 timeslots 2
 no yellow generation
 no yellow detection
!
interface Multilink6
 ip address 37.0.0.1 255.0.0.0
 ppp multilink interleave
 tag-switching ip
 load-interval 30
 multilink-group 6
!
interface Serial1/3:1
 encapsulation ppp
 no ip address
 ppp multilink
 tx-queue-limit 26
 multilink-group 6
 peer neighbor-route
!
interface Serial1/3:2
 encapsulation ppp
 no ip address
 ppp multilink
 tx-queue-limit 26
 multilink-group 6
 peer neighbor-route
Sample Multilink PPP Configuration for 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 1/1/3
 framing esf
 clock source internal
 linecode b8zs
 channel-group 1 timeslots 1
 channel-group 2 timeslots 2
 no yellow generation
 no yellow detection
!
interface Multilink6
 ip address 37.0.0.2 255.0.0.0
 ppp multilink interleave
 tag-switching ip
 load-interval 30
 multilink-group 6
!
interface Serial1/1/3:1
 encapsulation ppp
 no ip address
 ppp multilink
 tx-queue-limit 26
 multilink-group 6
 peer neighbor-route
!
interface Serial1/1/3:2
 encapsulation ppp
 no ip address
 ppp multilink
 tx-queue-limit 26
 multilink-group 6
 peer neighbor-route
Sample 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 Serial1/0:1
Building configuration...
!
mpls label protocol ldp
ip cef
ip vrf vpn2
 rd 200:1
 route-target export 200:1
 route-target import 200:1
!
controller T1 1/0
 framing esf
 clock source internal
 linecode b8zs
 channel-group 1 timeslots 1
 channel-group 2 timeslots 2
 no yellow generation
 no yellow detection
!
interface Serial1/0:1
 no ip address
 encapsulation ppp
 tx-ring-limit 26
 ppp multilink
 ppp multilink group 1
!
interface Serial1/0:2
 no ip address
 encapsulation ppp
 tx-ring-limit 26
 ppp multilink
 ppp multilink group 1
!
interface Multilink1
 ip vrf forwarding vpn2
 ip address 35.0.0.2 255.0.0.0
 no peer neighbor-route
 load-interval 30
 ppp multilink
 ppp multilink interleave
 ppp multilink group 1
!
!
router ospf 200
 log-adjacency-changes
 auto-cost reference-bandwidth 1000
 redistribute connected subnets
 passive-interface Multilink1
 network 10.0.0.7 0.0.0.0 area 200
 network 31.0.0.0 0.255.255.255 area 200
!
!
 router bgp 200
 no bgp default ipv4-unicast
 bgp log-neighbor-changes
 neighbor 10.0.0.11 remote-as 200
 neighbor 10.0.0.11 update-source Loopback0
 !
 address-family vpnv4
 neighbor 10.0.0.11 activate
 neighbor 10.0.0.11 send-community extended
 bgp scan-time import 5
 exit-address-family
 !
 address-family ipv4 vrf vpn2
 redistribute connected
 neighbor 35.0.0.1 remote-as 300
 neighbor 35.0.0.1 activate
 neighbor 35.0.0.1 as-override
 neighbor 35.0.0.1 advertisement-interval 5
 no auto-summary
 no synchronization
 exit-address-family
Enabling CEF or Distributed CEF: Example

The following example shows how to enable CEF for MLPPP configurations:
Router> enable
Router# configure terminal 
Router(config)# ip cef 
The following example shows how to enable dCEF for dMLPPP configurations:
Router> enable
Router# configure terminal 
Router(config)# ip cef distribute
Creating a Multilink Bundle: Example

The following example shows how to create a multilink bundle:
interface multilink1
 ip address 10.0.0.0 10.255.255.255
 ppp chap hostname group 1
 ppp multilink
 multilink-group 1
Assigning an Interface to a Multilink Bundle: Example

The following example shows how to create four multilink interfaces with distributed CEF switching and MLPPP enabled. Each of the newly created interfaces is added to a multilink bundle.
interface multilink1
 ip address 10.0.0.0 10.255.255.255
 ppp chap hostname group 1
 ppp multilink
 multilink-group 1
	 
interface serial 1/0/0/:1
 no ip address
 encapsulation ppp
 ip route-cache distributed
 no keepalive
 ppp multilink
 multilink-group 1
interface serial 1/0/0/:2
 no ip address
 encapsulation ppp
 ip route-cache distributed
 no keepalive
 ppp chap hostname group 1
 ppp multilink
 multilink-group 1
interface serial 1/0/0/:3
 no ip address
 encapsulation ppp
 ip route-cache distributed
 no keepalive
 ppp chap hostname group 1
 ppp multilink
 multilink-group 1
interface serial 1/0/0/:4
 no ip address
 encapsulation ppp
 ip route-cache distributed
 no keepalive
 ppp chap hostname group 1
 ppp multilink
 multilink-group 
Additional References

The following sections provide references related to the MPLS—Multilink PPP Support feature:

•Related Documents

•Standards

•MIBs

•RFCs

•Technical Assistance

Related Documents

Related Topic

Document Title

Configuration tasks for Distributed MLPPP 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

Configuring Media-Independent PPP and Multilink PPP

Configuration tasks for the Diff-Serv-aware MPLS Traffic Engineering feature

Diff-Serv-aware MPLS Traffic Engineering (DS-TE)

Configuration tasks for the MPLS QoS multi-VC mode feature

MPLS QoS Multi-VC Mode for PA-A3

Configuration tasks for MPLS VPNs

MPLS Virtual Private Networks (VPNs)

Configuration tasks for MPLS VPN CSC

MPLS VPN Carrier Supporting Carrier

Configuration tasks for MPLS VPN CSC with IPv4 BGP label distribution

MPLS VPN—Carrier Supporting Carrier—IPv4 BGP Label Distribution

Configuration tasks for MPLS VPN Inter-AS with IPv4 BGP label distribution

MPLS VPN—Inter-AS—IPv4 BGP Label Distribution

Standards

Standards

Title

No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature.

—

MIBs

MIBs

MIBs Link

No new or modified MIBs are supported by this feature, and support for existing MIBs has not been modified by this feature.

To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL:

http://www.cisco.com/go/mibs

RFCs

RFCs

Title

RFC 1990

The PPP Multilink Protocol (MP)

Technical Assistance

Description

Link

Technical Assistance Center (TAC) home page, containing 30,000 pages of searchable technical content, including links to products, technologies, solutions, technical tips, and tools. Registered Cisco.com users can log in from this page to access even more content.

http://www.cisco.com/public/support/tac/home.shtml

Glossary

bundle—A group of interfaces connected by parallel links between two systems that have agreed to do MLPPP over those links.

CBWFQ—class-based weighted fair queuing. A queuing option that extends the standard WFQ functionality to provide support for user-defined traffic classes.

CEF—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 CEF 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 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 IGRP, OSPF, and RIP.

IGRP—Interior Gateway Routing Protocol. An IGP developed by Cisco to address the issues associated with routing in large, heterogeneous networks. Compare with EIGRP.

IS-IS—Intermediate System-to-Intermediate System. An OSI link-state hierarchical routing protocol, based on DECnet Phase V routing, in which ISs (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 queuing. A QoS queuing 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).

MLPPP—Multilink Point-to-Point Protocol. A method of splitting, recombining, and sequencing datagrams across multiple logical links. The use of MLPPP 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 IGP routing algorithm proposed as a successor to 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, IPX, and ARA). PPP also has built-in security mechanisms (such as CHAP and PAP). PPP relies on two protocols: LCP and NCP.

RIP—Routing Information Protocol. A version of IGP that is supplied with UNIX BSD systems. 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 CEF, 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 queuing. 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.

Note Refer to the Cisco Dictionary of Internetworking Terms and Acronyms for terms not included in this glossary.

Copyright © 2004 Cisco Systems, Inc. All rights reserved.

Hierarchical Navigation

Cisco IOS Software Releases 12.2 T

MPLS�Multilink PPP Support

Downloads

Table Of Contents

MPLS—Multilink PPP Support

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 CEF or Distributed CEF Switching

Prerequisites

SUMMARY STEPS

DETAILED STEPS

Creating a Multilink Bundle

SUMMARY STEPS

DETAILED STEPS

Assigning an Interface to a Multilink Bundle

SUMMARY STEPS

DETAILED STEPS

Troubleshooting Tips

Disabling PPP Multilink Fragmentation

SUMMARY STEPS

DETAILED STEPS

Verifying the Multilink PPP Configuration

SUMMARY STEPS

DETAILED STEPS

Examples

Configuration Examples for MPLS—Multilink PPP Support

Sample MPLS—Multilink PPP Support Configurations

Sample Multilink PPP Configuration on Cisco 7200 Series Router

Sample Multilink PPP Configuration for Cisco 7500 Series Router

Sample Multilink PPP Configuration on an MPLS CSC PE Router

Enabling CEF or Distributed CEF: Example

Creating a Multilink Bundle: Example

Assigning an Interface to a Multilink Bundle: Example

Additional References

Related Documents

Standards

MIBs

RFCs

Technical Assistance

Glossary

Copyright © 2004 Cisco Systems, Inc. All rights reserved.