Cisco IOS XR Interface and Hardware Component Configuration Guide for the Cisco XR 12000 Series Router, Release 4.3.x

Contents
Prerequisites for Configuring PPP
Information About PPP
How to Configure PPP
Configuration Examples for PPP
Additional References

Configuring PPP on Cisco IOS XR Software

This module describes the configuration of Point-to-Point Protocol (PPP) on POS and serial interfaces on the Cisco XR 12000 Series Router.

Feature History for Configuring PPP Interfaces


Release	Modification
Release 3.3.0	Support for serial interfaces with PPP encapsulation was introduced on the Cisco XR 12000 Series Router.
Release 3.4.1	Support for Multilink PPP was introduced on the Cisco XR 12000 Series Router.
Release 4.0.0	Support for the following features was added for the 8-Port Channelized T1/E1 SPA on the Cisco XR 12000 Series Router: •IPHC over MLPPP •MLPPP •MLPPP/LFI

on Cisco IOS XR Software

•Prerequisites for Configuring PPP

•Information About PPP

•How to Configure PPP

•Configuration Examples for PPP

•Additional References

Prerequisites for Configuring PPP

You must be in a user group associated with a task group that includes the proper task IDs. The command reference guides include the task IDs required for each command. If you suspect user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Before you can configure PPP authentication on a POS or serial interface, be sure that the following tasks and conditions are met:

•Your hardware must support POS or serial interfaces.

•You have enabled PPP encapsulation on your interface with the encap ppp command, as described in the appropriate module:

–To enable PPP encapsulation on a POS interface, see the Configuring POS Interfaces on Cisco IOS XR Software module in this manual.

–To enable PPP encapsulation on a serial interface, see the Configuring Serial Interfaces on Cisco IOS XR Sotware module in this manual.

Information About PPP

To configure PPP and related features, you should understand the information in this section:

•PPP Authentication

•Multilink PPP

•T3 SONET Channels

PPP Authentication

When PPP authentication is configured on an interface, a host requires that the other host uniquely identify itself with a secure password before establishing a PPP connection. The password is unique and is known to both hosts.

PPP supports the following authentication protocols:

•Challenge-Handshake Authentication Protocol (CHAP)

•Microsoft extension to the CHAP protocol (MS-CHAP)

•Password Authentication Protocol (PAP).

When you first enable PPP on a POS or serial interface, no authentication is enabled on the interface until you configure a CHAP, MS-CHAP, or PAP secret password under that interface. Keep the following information in mind when configuring PPP on an interface:

•CHAP, MS-CHAP, and PAP can be configured on a single interface; however, only one authentication method is used at any one time. The order in which the authentication protocols are used is determined by the peer during the LCP negotiations. The first authentication method used is the one that is also supported by the peer.

•PAP is the least secure authentication protocol available on POS and serial interfaces. To ensure higher security for information that is sent over POS and serial interfaces, we recommend configuring CHAP or MS-CHAP authentication in addition to PAP authentication.

•Enabling or disabling PPP authentication does not effect the local router's willingness to authenticate itself to the remote device.

•The ppp authentication command is also used to specify the order in which CHAP, MS-CHAP, and PAP authentication is selected on the interface. You can enable CHAP, MS-CHAP, or PAP in any order. If you enable all three methods, the first method specified is requested during link negotiation. If the peer suggests using the second method, or refuses the first method, the second method is tried. Some remote devices support only one method. Base the order in which you specify methods on the remote device's ability to correctly negotiate the appropriate method and on the level of data line security you require. PAP usernames and passwords are sent as clear text strings, which can be intercepted and reused.

Caution

If you use a list-name value that was not configured with the aaa authentication ppp command, your interface cannot authenticate the peer. For details on implementing the aaa authentication command with the ppp keyword, see the Authentication, Authorization, and Accounting Commands on Cisco IOS XR Software module of Cisco IOS XR System Security Command Referenc e and Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.

PAP Authentication

PAP provides a simple method for a remote node to establish its identity using a two-way handshake. After a PPP link is established between two hosts, a username and password pair is repeatedly sent by the remote node across the link (in clear text) until authentication is acknowledged, or until the connection is terminated.

PAP is not a secure authentication protocol. Passwords are sent across the link in clear text and there is no protection from playback or trial-and-error attacks. The remote node is in control of the frequency and timing of the login attempts.

CHAP Authentication

CHAP is defined in RFC 1994, and it verifies the identity of the peer by means of a three-way handshake. The steps that follow provide a general overview of the CHAP process:

Step 1 The CHAP authenticator sends a challenge message to the peer.

Step 2 The peer responds with a value calculated through a one-way hash function.

Step 3 The authenticator checks the response against its own calculation of the expected hash value. If the values match, then the authentication is successful. If the values do not match, then the connection is terminated.

This authentication method depends on a CHAP password known only to the authenticator and the peer. The CHAP password is not sent over the link. Although the authentication is only one-way, you can negotiate CHAP in both directions, with the help of the same CHAP password set for mutual authentication.

Note For CHAP authentication to be valid, the CHAP password must be identical on both hosts.

MS-CHAP Authentication

Microsoft Challenge Handshake Authentication Protocol (MS-CHAP) is the Microsoft version of CHAP and is an extension to RFC 1994. MS-CHAP follows the same authentication process used by CHAP. In this case, however, authentication occurs between a PC using Microsoft Windows NT or Microsoft Windows 95 and a Cisco router or access server acting as a network access server (NAS).

Note For MS-CHAP authentication to be valid, the MS-CHAP password must be identical on both hosts.

Multilink PPP

Multilink Point-to-Point Protocol (MLPPP) provides a method for combining multiple physical links into one logical link. The implementation combines multiple PPP interfaces into one multilink interface. MLPPP performs the fragmenting, reassembling, and sequencing of datagrams across multiple PPP links.

Link Fragmentation and Interleaving (LFI) is designed for MLPPP interfaces and is required when integrating voice and data on low-speed interfaces.

Link Fragmentation and Interleaving (LFI) provides stability for delay-sensitive traffic, such as voice or video, traveling on the same circuit as data. Voice is susceptible to increased latency and jitter when the network processes large packets on low-speed interfaces. LFI reduces delay and jitter by fragmenting large datagrams and interleaving them with low-delay traffic packets.

Figure 23 Link Fragmentation Interleave

MLPPP Feature Summary

MLPPP in Cisco IOS XR provides the same features that are supported on PPP Serial interfaces with the exception of QoS. It also provides the following additional features:

•Fragment sizes of 128, 256, and 512 bytes.

•Long sequence numbers (24-bit).

•Lost fragment detection timeout period of 80 milliseconds.

•Minimum-active-links configuration option.

•LCP echo request/reply support over multilink interface.

•Full T1 and E1 framed and unframed links.

IPHC Over MLPPP

The 8-Port Channelized T1/E1 SPA supports IPHC over MLPPP. For more information about IPHC and how to configure it, see the "Configuring Serial Interfaces on Cisco IOS XR Software" module in the Cisco IOS XR Interface and Hardware Component Configuration Guide for the Cisco XR 12000 Series Router.

T3 SONET Channels

The Cisco XR 12000 Series Router supports T3 channelized SONET on the following hardware:

•Cisco 1-Port Channelized OC-3/STM-1 SPA

•Cisco 1-Port Channelized OC-12/DS0 SPA

•Cisco 1-Port Channelized OC-48/STM-16 SPA

Channelized SONET provides the ability to transport multiple T3 channels over the same physical link.

For more detailed information about configuring channelized SONET, T3 and T1 controllers, serial interfaces, and SONET APS, see the following related modules:

•"Configuring Channelized SONET/SDH on Cisco IOS XR Software"

•"Configuring Clear Channel SONET Controllers on Cisco IOS XR Software"

•"Configuring Clear Channel T3/E3 and Channelized T3 and T1/E1 Controllers on Cisco IOS XR Software"

•"Configuring Serial Interfaces on Cisco IOS XR Sotware"

How to Configure PPP

This section includes the following procedures:

•Modifying the Default PPP Configuration

•Configuring PPP Authentication

•Disabling an Authentication Protocol

•Configuring Multilink PPP

Modifying the Default PPP Configuration

When you first enable PPP on an interface, the following default configuration applies:

•The interface resets itself immediately after an authentication failure.

•The maximum number of configuration requests without response permitted before all requests are stopped is 10.

•The maximum number of consecutive Configure Negative Acknowledgments (CONFNAKs) permitted before terminating a negotiation is 5.

•The maximum number of terminate requests (TermReqs) without response permitted before the Link Control Protocol (LCP) or Network Control Protocol (NCP) is closed is 2.

•Maximum time to wait for a response to an authentication packet is 10 seconds.

•Maximum time to wait for a response during PPP negotiation is 3 seconds.

This task explains how to modify the basic PPP configuration on serial and POS interfaces that have PPP encapsulation enabled. The commands in this task apply to all authentication types supported by PPP (CHAP, MS-CHAP, and PAP).

Prerequisites

You must enable PPP encapsulation on the interface with the encapsulation ppp command.

•To enable PPP encapsulation on a POS interface, see the Configuring POS Interfaces on Cisco IOS XR Software module in this manual.

•To enable PPP encapsulation on an interface, see the Configuring Serial Interfaces on Cisco IOS XR Sotware module in this manual.

SUMMARY STEPS

1. configure

2. interface type interface-path-id

3. ppp max-bad-auth retries

4. ppp max-configure retries

5. ppp max-failure retries

6. ppp max-terminate number

7. ppp timeout authentication seconds

8. ppp timeout retry seconds

9. end
or
commit

10. show ppp interfaces {type interface-path-id | all | brief {type interface-path-id | all | location node-id} | detail {type interface-path-id | all | location node-id} | location node-id}

DETAILED STEPS


	Command or Action	Purpose
Step 1	configure Example: RP/0/0/CPU0:router# configure	Enters global configuration mode.
Step 2	interface type interface-path-id Example: RP/0/0/CPU0:router(config)# interface serial 0/4/0/1	Enters interface configuration mode.
Step 3	ppp max-bad-auth retries Example: RP/0/0/CPU0:router(config-if)# ppp max-bad-auth 3	(Optional) Configures the number of authentication retries allowed on an interface after a PPP authentication failure. •If you do not specify the number of authentication retries allowed, the router resets itself immediately after an authentication failure. •Replace the retries argument with number of retries after which the interface is to reset itself, in the range from 0 through 10. •The default is 0 retries. •The ppp max-bad-auth command applies to any interface on which PPP encapsulation is enabled.
Step 4	ppp max-configure retries Example: RP/0/0/CPU0:router(config-if)# ppp max-configure 4	(Optional) Specifies the maximum number of configure requests to attempt (without response) before the requests are stopped. •Replace the retries argument with the maximum number of configure requests retries, in the range from 4 through 20. •The default maximum number of configure requests is 10. •If a configure request message receives a reply before the maximum number of configure requests are sent, further configure requests are abandoned.
Step 5	ppp max-failure retries Example: RP/0/0/CPU0:router(config-if)# ppp max-failure 3	(Optional) Configures the maximum number of consecutive Configure Negative Acknowledgments (CONFNAKs) permitted before a negotiation is terminated. •Replace the retries argument with the maximum number of CONFNAKs to permit before terminating a negotiation, in the range from 2 through 10. •The default maximum number of CONFNAKs is 5.
Step 6	ppp max-terminate number Example: RP/0/0/CPU0:router(config-if)# ppp max-terminate 5	(Optional) Configures the maximum number of terminate requests (TermReqs) to send without reply before the Link Control Protocol (LCP) or Network Control Protocol (NCP) is closed. •Replace the number argument with the maximum number of TermReqs to send without reply before closing down the LCP or NCP. Range is from 2 to 10. •The default maximum number of TermReqs is 2.
Step 7	ppp timeout authentication seconds Example: RP/0/0/CPU0:router(config-if)# ppp timeout authentication 20	(Optional) Sets PPP authentication timeout parameters. •Replace the seconds argument with the maximum time, in seconds, to wait for a response to an authentication packet. Range is from 3 to 30 seconds. •The default authentication time is 10 seconds, which should allow time for a remote router to authenticate and authorize the connection and provide a response. However, it is also possible that it will take much less time than 10 seconds. In such cases, use the ppp timeout authentication command to lower the timeout period to improve connection times in the event that an authentication response is lost.
Step 8	ppp timeout retry seconds Example: RP/0/0/CPU0:router(config-if)# ppp timeout retry 8	(Optional) Sets PPP timeout retry parameters. •Replace the seconds argument with the maximum time, in seconds, to wait for a response during PPP negotiation. Range is from 1 to 10 seconds. •The default is 3 seconds.
Step 9	end or commit Example: RP/0/0/CPU0:router(config-if)# end or RP/0/0/CPU0:router(config-if)# commit	Saves configuration changes. •When you issue the end command, the system prompts you to commit changes: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: –Entering yes saves configuration changes to the running configuration file, exits the configuration session, and returns the router to EXEC mode. –Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. –Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. •Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session.
Step 10	show ppp interfaces {type interface-path-id \| all \| brief {type interface-path-id \| all \| location node-id} \| detail {type interface-path-id \| all \| location node-id} \| location node-id} Example: RP/0/0/CPU0:router# show ppp interfaces serial 0/2/0/0	Verifies the PPP configuration for an interface or for all interfaces that have PPP encapsulation enabled.

Configuring PPP Authentication

This section contains the following procedures:

•Enabling PAP, CHAP, and MS-CHAP Authentication

•Configuring a PAP Authentication Password

•Configuring a CHAP Authentication Password

•Configuring an MS-CHAP Authentication Password

Enabling PAP, CHAP, and MS-CHAP Authentication

This task explains how to enable PAP, CHAP, and MS-CHAP authentication on a serial or POS interface.

Prerequisites

You must enable PPP encapsulation on the interface with the encapsulation ppp command, as described in the following modules:

•To enable PPP encapsulation on a POS interface, see the Configuring POS Interfaces on Cisco IOS XR Software module in this manual.

•To enable PPP encapsulation on an interface, see the Configuring Serial Interfaces on Cisco IOS XR Sotware module in this manual.

SUMMARY STEPS

1. configure

2. interface type interface-path-id

3. ppp authentication protocol [protocol [protocol]] [list-name | default]

4. end
or
commit

5. show ppp interfaces {type interface-path-id | all | brief {type interface-path-id | all | location node-id} | detail {type interface-path-id | all | location node-id} | location node-id}

DETAILED STEPS


	Command or Action	Purpose
Step 1	configure Example: RP/0/0/CPU0:router# configure	Enters global configuration mode.
Step 2	interface type interface-path-id Example: RP/0/0/CPU0:router(config)# interface serial 0/4/0/1	Enters interface configuration mode.
Step 3	ppp authentication protocol [protocol [protocol]] [list-name \| default] Example: RP/0/0/CPU0:router(config-if)# ppp authentication chap pap MIS-access	Enables CHAP, MS-CHAP, or PAP on an interface, and specifies the order in which CHAP, MS-CHAP, and PAP authentication is selected on the interface. •Replace the protocol argument with pap, chap, or ms-chap. •Replace the list name argument with the name of a list of methods of authentication to use. To create a list, use the aaa authentication ppp command, as described in the Authentication, Authorization, and Accounting Commands on Cisco IOS XR Software module of the Cisco IOS XR System Security Command Reference. •If no list name is specified, the system uses the default. The default list is designated with the aaa authentication ppp command, as described in the Authentication, Authorization, and Accounting Commands on Cisco IOS XR Software module of the Cisco IOS XR System Security Command Reference.
Step 4	end or commit Example: RP/0/0/CPU0:router(config-if)# end or RP/0/0/CPU0:router(config-if)# commit	Saves configuration changes. •When you issue the end command, the system prompts you to commit changes: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: –Entering yes saves configuration changes to the running configuration file, exits the configuration session, and returns the router to EXEC mode. –Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. –Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. •Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session.
Step 5	show ppp interfaces {type interface-path-id \| all \| brief {type interface-path-id \| all \| location node-id} \| detail {type interface-path-id \| all \| location node-id} \| location node-id} Example: RP/0/0/CPU0:router# show ppp interfaces serial 0/2/0/0	Displays PPP state information for an interface. •Enter the type interface-path-id argument to display PPP information for a specific interface. •Enter the brief keyword to display brief output for all interfaces on the router, for a specific interface instance, or for all interfaces on a specific node. •Enter the all keyword to display detailed PPP information for all nodes installed in the router. •Enter the location node-id keyword argument to display detailed PPP information for the designated node. There are seven possible PPP states applicable for either the Link Control Protocol (LCP) or the Network Control Protocol (NCP).

Where To Go Next

Configure a PAP, CHAP, or MS-CHAP authentication password, as described in the appropriate section:

•If you enabled PAP on an interface, configure a PAP authentication username and password, as described in the "Configuring a PAP Authentication Password" section.

•If you enabled CHAP on an interface, configure a CHAP authentication password, as described in the "Configuring a CHAP Authentication Password" section

•If you enabled MS-CHAP on an interface, configure an MS-CHAP authentication password, as described in the "Configuring an MS-CHAP Authentication Password" section

Configuring a PAP Authentication Password

This task explains how to enable and configure PAP authentication on a serial or POS interface.

Note PAP is the least secure authentication protocol available on POS and interfaces. To ensure higher security for information that is sent over POS and interfaces, we recommend configuring CHAP or MS-CHAP authentication in addition to PAP authentication.

Prerequisites

You must enable PAP authentication on the interface with the ppp authentication command, as described in the "Enabling PAP, CHAP, and MS-CHAP Authentication" section.

SUMMARY STEPS

1. configure

2. interface type interface-path-id

3. ppp pap sent-username username password [clear | encrypted] password

4. end
or
commit

5. show running-config

DETAILED STEPS


	Command or Action	Purpose
Step 1	configure Example: RP/0/0/CPU0:router# configure	Enters global configuration mode.
Step 2	interface type interface-path-id Example: RP/0/0/CPU0:router(config)# interface serial 0/4/0/1	Enters interface configuration mode.
Step 3	ppp pap sent-username username password [clear \| encrypted] password Example: RP/0/0/CPU0:router(config-if)# ppp pap sent-username xxxx password notified	Enables remote Password Authentication Protocol (PAP) support for an interface, and includes the sent-username and password commands in the PAP authentication request packet to the peer. •Replace the username argument with the username sent in the PAP authentication request. •Enter password clear to select cleartext encryption for the password, or enter password encrypted if the password is already encrypted. •The ppp pap sent-username command allows you to replace several username and password configuration commands with a single copy of this command on interfaces. •You must configure the ppp pap sent-username command for each interface. •Remote PAP support is disabled by default.
Step 4	end or commit Example: RP/0/0/CPU0:router(config-if)# end or RP/0/0/CPU0:router(config-if)# commit	Saves configuration changes. •When you issue the end command, the system prompts you to commit changes: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: –Entering yes saves configuration changes to the running configuration file, exits the configuration session, and returns the router to EXEC mode. –Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. –Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. •Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session.
Step 5	show running-config Example: RP/0/0/CPU0:router# show running-config	Verifies PPP authentication information for interfaces that have PPP encapsulation enabled.

Configuring a CHAP Authentication Password

This task explains how to enable CHAP authentication and configure a CHAP password on a serial or POS interface.

Prerequisites

You must enable CHAP authentication on the interface with the ppp authentication command, as described in the "Enabling PAP, CHAP, and MS-CHAP Authentication" section.

Restrictions

The same CHAP password must be configured on both host endpoints.

SUMMARY STEPS

1. configure

2. interface type interface-path-id

3. ppp chap password [clear | encrypted] password

4. end
or
commit

5. show running-config

DETAILED STEPS


	Command or Action	Purpose
Step 1	configure Example: RP/0/0/CPU0:router# configure	Enters global configuration mode.
Step 2	interface type interface-path-id Example: RP/0/0/CPU0:router(config)# interface serial 0/4/0/1	Enters interface configuration mode.
Step 3	ppp chap password [clear \| encrypted] password Example: RP/0/0/CPU0:router(config-if)# ppp chap password clear xxxx	Enables CHAP authentication on the specified interface, and defines an interface-specific CHAP password. •Enter clear to select cleartext encryption, or encrypted if the password is already encrypted. •Replace the password argument with a cleartext or already-encrypted password. This password is used to authenticate secure communications among a collection of routers. •The ppp chap password command is used for remote CHAP authentication only (when routers authenticate to the peer) and does not effect local CHAP authentication.This command is useful when you are trying to authenticate a peer that does not support this command (such as a router running an older Cisco IOS XR software image). •The CHAP secret password is used by the routers in response to challenges from an unknown peer.
Step 4	end or commit Example: RP/0/0/CPU0:router(config-if)# end or RP/0/0/CPU0:router(config-if)# commit	Saves configuration changes. •When you issue the end command, the system prompts you to commit changes: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: –Entering yes saves configuration changes to the running configuration file, exits the configuration session, and returns the router to EXEC mode. –Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. –Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. •Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session.
Step 5	show running-config Example: RP/0/0/CPU0:router# show running-config	Verifies PPP authentication information for interfaces that have PPP encapsulation enabled.

Configuring an MS-CHAP Authentication Password

This task explains how to enable MS-CHAP authentication and configure an MS-CHAP password on a serial or POS interface.

Prerequisites

You must enable MS-CHAP authentication on the interface with the ppp authentication command, as described in the "Enabling PAP, CHAP, and MS-CHAP Authentication" section.

Restrictions

The same MS-CHAP password must be configured on both host endpoints.

SUMMARY STEPS

1. configure

2. interface type interface-path-id

3. ppp ms-chap password [clear | encrypted] password

4. end
or
commit

5. show running-config

DETAILED STEPS


	Command or Action	Purpose
Step 1	configure Example: RP/0/0/CPU0:router# configure	Enters global configuration mode.
Step 2	interface type interface-path-id Example: RP/0/0/CPU0:router(config)# interface serial 0/4/0/1	Enters interface configuration mode.
Step 3	ppp ms-chap password [clear \| encrypted] password Example: RP/0/0/CPU0:router(config-if)# ppp ms-chap password clear xxxx	Enables a router calling a collection of routers to configure a common Microsoft Challenge Handshake Authentication (MS-CHAP) secret password. The MS-CHAP secret password is used by the routers in response to challenges from an unknown peer.
Step 4	end or commit Example: RP/0/0/CPU0:router(config-if)# end or RP/0/0/CPU0:router(config-if)# commit	Saves configuration changes. •When you issue the end command, the system prompts you to commit changes: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: –Entering yes saves configuration changes to the running configuration file, exits the configuration session, and returns the router to EXEC mode. –Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. –Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. •Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session.
Step 5	show running-config Example: RP/0/0/CPU0:router# show running-config	Verifies PPP authentication information for interfaces that have PPP encapsulation enabled.

Disabling an Authentication Protocol

This section contains the following procedures:

•Disabling PAP Authentication on an Interface

•Disabling CHAP Authentication on an Interface

•Disabling MS-CHAP Authentication on an Interface

Disabling PAP Authentication on an Interface

This task explains how to disable PAP authentication on a serial or POS interface.

SUMMARY STEPS

1. configure

2. interface type interface-path-id

3. ppp pap refuse

4. end
or
commit

5. show running-config

DETAILED STEPS


	Command or Action	Purpose
Step 1	configure Example: RP/0/0/CPU0:router# configure	Enters global configuration mode.
Step 2	interface type interface-path-id Example: RP/0/0/CPU0:router(config)# interface serial 0/4/0/1	Enters interface configuration mode.
Step 3	ppp pap refuse Example: RP/0/0/CPU0:router(config-if)# ppp pap refuse	Refuses Password Authentication Protocol (PAP) authentication from peers requesting it. •If outbound Challenge Handshake Authentication Protocol (CHAP) has been configured (using the ppp authentication command), CHAP will be suggested as the authentication method in the refusal packet. •PAP authentication is disabled by default.
Step 4	end or commit Example: RP/0/0/CPU0:router(config-if)# end or RP/0/0/CPU0:router(config-if)# commit	Saves configuration changes. •When you issue the end command, the system prompts you to commit changes: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: –Entering yes saves configuration changes to the running configuration file, exits the configuration session, and returns the router to EXEC mode. –Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. –Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. •Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session.
Step 5	show running-config Example: RP/0/0/CPU0:router# show running-config	Verifies PPP authentication information for interfaces that have PPP encapsulation enabled.

Disabling CHAP Authentication on an Interface

This task explains how to disable CHAP authentication on a serial or POS interface.

SUMMARY STEPS

1. configure

2. interface type interface-path-id

3. ppp chap refuse

4. end
or
commit

5. show running-config

DETAILED STEPS


	Command or Action	Purpose
Step 1	configure Example: RP/0/0/CPU0:router# configure	Enters global configuration mode.
Step 2	interface type interface-path-id Example: RP/0/0/CPU0:router(config)# interface serial 0/4/0/1	Enters interface configuration mode.
Step 3	ppp chap refuse Example: RP/0/0/CPU0:router(config-if)# ppp chap refuse	Refuses CHAP authentication from peers requesting it. After you enter the ppp chap refuse command under the specified interface, all attempts by the peer to force the user to authenticate with the help of CHAP are refused. •CHAP authentication is disabled by default. •If outbound Password Authentication Protocol (PAP) has been configured (using the ppp authentication command), PAP will be suggested as the authentication method in the refusal packet.
Step 4	end or commit Example: RP/0/0/CPU0:router(config-if)# end or RP/0/0/CPU0:router(config-if)# commit	Saves configuration changes. •When you issue the end command, the system prompts you to commit changes: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: –Entering yes saves configuration changes to the running configuration file, exits the configuration session, and returns the router to EXEC mode. –Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. –Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. •Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session.
Step 5	show running-config Example: RP/0/0/CPU0:router# show running-config	Verifies PPP authentication information for interfaces that have PPP encapsulation enabled.

Disabling MS-CHAP Authentication on an Interface

This task explains how to disable MS-CHAP authentication on a serial or POS interface.

SUMMARY STEPS

1. configure

2. interface type interface-path-id

3. ppp ms-chap refuse

4. end
or
commit

5. show running-config

DETAILED STEPS


	Command or Action	Purpose
Step 1	configure Example: RP/0/0/CPU0:router# configure	Enters global configuration mode.
Step 2	interface type interface-path-id Example: RP/0/0/CPU0:router(config)# interface serial 0/4/0/1	Enters interface configuration mode.
Step 3	ppp ms-chap refuse Example: RP/0/0/CPU0:router(config-if)# ppp ms-chap refuse	Refuses MS-CHAP authentication from peers requesting it. After you enter the ppp ms-chap refuse command under the specified interface, all attempts by the peer to force the user to authenticate with the help of MS-CHAP are refused. •MS-CHAP authentication is disabled by default. •If outbound Password Authentication Protocol (PAP) has been configured (using the ppp authentication command), PAP will be suggested as the authentication method in the refusal packet.
Step 4	end or commit Example: RP/0/0/CPU0:router(config-if)# end or RP/0/0/CPU0:router(config-if)# commit	Saves configuration changes. •When you issue the end command, the system prompts you to commit changes: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: –Entering yes saves configuration changes to the running configuration file, exits the configuration session, and returns the router to EXEC mode. –Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. –Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. •Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session.
Step 5	show running-config Example: RP/0/0/CPU0:router# show running-config	Verifies PPP authentication information for interfaces that have PPP encapsulation enabled.

Configuring Multilink PPP

This section contains the following procedures:

•Prerequisites

•Restrictions

•Configuring the Controller

•Configuring the Interfaces

•Configuring MLPPP Optional Features

Prerequisites

Before configuring MLPPP, be sure you have one of the SPAs listed here installed. Both MLPPP and LFI are supported on the following SIPs and SPAs:

•Cisco XR 12000 SIP-401

•Cisco XR 12000 SIP-501

•Cisco XR 12000 SIP-601

•Cisco 1-Port Channelized STM-1/OC-3 SPA

•Cisco 1-Port Channelized OC-12/STM-4 SPA

•Cisco 2-Port and 4-Port Channelized T3 SPAs (SPA-2XCT3/DS0, SPA-4XCT3/DS0)

•Cisco 8-Port Channelized T1/E1 SPA

•Cisco 1-Port Channelized OC-12 Line Card (Supports MLPPP only)

Restrictions

MLPPP for Cisco IOS XR software has the following restrictions:

•Only full rate T1s are supported.

•All links in a bundle must belong to the same SPA.

•All links in a bundle must operate at the same speed.

•A maximum of 12 links per bundle is supported.

•A maximum of 28 bundles is supported on the 2-Port Channelized T3 SPA.

•A maximum of 56 bundles is supported on the 4-Port Channelized T3 SPA.

•A maximum of 224 bundles is supported per line card.

•All serial links in an MLPPP bundle inherit the value of the mtu command from the multilink interface. Therefore, you should not configure the mtu command on a serial interface before configuring it as a member of an MLPPP bundle. The Cisco IOS XR software blocks the following:

–Attempts to configure a serial interface as a member of an MLPPP bundle if the interface is configured with a nondefault MTU value.

–Attempts to change the mtu command value for a serial interface that is configured as a member of an MLPPP bundle.

In Cisco IOS XR software, multilink processing is controlled by a hardware module called the Multilink Controller, which consists of an ASIC, network processor, and CPU working in conjunction. The MgmtMultilink Controller makes the multilink interfaces behave like the serial interfaces of channelized SPAs.

Configuring the Controller

Perform this task to configure the controller.

SUMMARY STEPS

1. configure

2. controller type interface-path-id

3. mode type

4. clock source {internal | line}

5. exit

6. controller t1 interface-path-id

7. channel-group channel-group-number

8. timeslots range

9. exit

10. exit

11. controller mgmtmultilink interface-path-id

12. bundle bundle-id

13. end
or
commit

DETAILED STEPS


	Command or Action	Purpose
Step 1	configure Example: RP/0/0/CPU0:router# configure	Enters global configuration mode.
Step 2	controller type interface-path-id Example: RP/0/0/CPU0:router(config)# controller t3 0/1/0/0	Enters controller configuration submode and specifies the controller name and instance identifier in rack/slot/module/port notation.
Step 3	mode type Example: RP/0/0/CPU0:router# mode t1	Configures the type of multilinks to channelize; for example, 28 T1s.
Step 4	clock source {internal \| line} Example: RP/0/0/CPU0:router(config-t3)# clock source internal	(Optional) Configures the clocking for the port. Note The default clock source is internal.
Step 5	exit Example: RP/0/0/CPU0:router(config-t3)# exit	Exits controller configuration mode.
Step 6	controller t1 interface-path-id Example: RP/0/0/CPU0:router(config)# controller t1 0/1/0/0/1	Enters T1 configuration mode.
Step 7	channel-group channel-group-number Example: RP/0/0/CPU0:router(config-t1)# channel-group 0	Creates a T1 channel group and enters channel group configuration mode for that channel group. Channel group numbers can range from 0 to 23.
Step 8	timeslots range Example: RP/0/0/CPU0:router(config-t1-channel_group)# timeslots 1-24	Associates one or more DS0 time slots to a channel group and creates an associated serial subinterface on that channel group. •Range is from 1 to 24 time slots. Note The time slot range must be from 1 to 24 for the resulting serial interface to be accepted into a MLPPP bundle.
Step 9	exit Example: RP/0/0/CPU0:router(config-t1-channel_group)# exit	Exits channel group configuration mode.
Step 10	exit Example: RP/0/0/CPU0:router(config-t1)# exit	Exits T1 configuration mode and enters global configuration mode.
Step 11	controller mgmtmultilink interface-path-id Example: RP/0/0/CPU0:router(config)# controller mgmtmultilink 0/1/0/0	Enters controller configuration submode for the management of multilink interfaces. Specify the controller name and instance identifier in rack/slot/module/port notation.
Step 12	bundle bundle-id Example: RP/0/0/CPU0:router(config-mgmtmultilink)# bundle 20	Creates a multilink interface with the specified bundle ID.
Step 13	end or commit Example: RP/0/0/CPU0:router(config-t3)# end or RP/0/0/CPU0:router(config-t3)# commit	Saves configuration changes. •When you issue the end command, the system prompts you to commit changes: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: –Entering yes saves configuration changes to the running configuration file, exits the configuration session, and returns the router to EXEC mode. –Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. –Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. •Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session.

Configuring the Interfaces

Perform this task to configure the interfaces.

Restrictions

–Attempts to configure a serial interface as a member of an MLPPP bundle if the interface is configured with a nondefault MTU value.

–Attempts to change the mtu command value for a serial interface that is configured as a member of an MLPPP bundle.

SUMMARY STEPS

1. configure

2. interface multilink interface-path-id

3. ipv4 address address/mask

4. multilink fragment-size bytes

5. keepalive {interval | disable}[retry]

6. exit

7. interface type interface-path-id

8. encapsulation type

9. multilink group group-id

10. end
or
commit

DETAILED STEPS


	Command or Action	Purpose
Step 1	configure Example: RP/0/0/CPU0:router# configure	Enters global configuration mode.
Step 2	interface multilink interface-path-id Example: RP/0/0/CPU0:router(config)# interface multilink 0/1/0/0/20	Specifies the multilink interface name and instance identifier in rack/slot/module/port/bundle-id notation, and enters interface configuration mode.
Step 3	ipv4 address ip-address Example: RP/0/0/CPU0:router(config-if)# ipv4 address 80.170.0.1/24	Assigns an IP address and subnet mask to the interface in the format: A.B.C.D/prefix or A.B.C.D/mask
Step 4	multilink fragment-size bytes Example: RP/0/0/CPU0:router(config-if)# multilink fragment-size 350	(Optional) Specifies the size of the multilink fragments, such as 128 bytes. Some fragment sizes may not be supported. The default is no fragments.
Step 5	keepalive {interval \| disable}[retry] Example: RP/0/0/CPU0:router(config-if)# keepalive disable	Sets the keepalive timer for the channel, where: •interval—Number of seconds (from 1 to 30) between keepalive messages. The default is 10. •disable—Turns off the keepalive timer. •retry—(Optional) Number of keepalive messages (from 1 to 255) that can be sent to a peer without a response before transitioning the link to the down state. The default is 3. Note To connect with some Cisco IOS devices, multilink keepalives need to be disabled on both devices.
Step 6	exit Example: RP/0/0/CPU0:router(config-if)# exit	Exits interface configuration mode and enters global configuration mode.
Step 7	interface type interface-path-id Example: RP/0/0/CPU0:router(config)# interface serial 0/1/0/0/1:0	Specifies the interface name and instance identifier in rack/slot/module/port/t1-number:channel-group notation, and enters interface configuration mode.
Step 8	encapsulation type Example: RP/0/0/CPU0:router(config-if)# encapsulation ppp	Specifies the type of encapsulation; in this case, PPP.
Step 9	multilink group group-id Example: RP/0/0/CPU0:router(config-if)# multilink group 20	Specifies the multilink group ID for this interface.
Step 10	end or commit Example: RP/0/0/CPU0:router(config-t3)# end or RP/0/0/CPU0:router(config-t3)# commit	Saves configuration changes. •When you issue the end command, the system prompts you to commit changes: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: –Entering yes saves configuration changes to the running configuration file, exits the configuration session, and returns the router to EXEC mode. –Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. –Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. •Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session.

Configuring MLPPP Optional Features

Perform this task to configure either of the following optional features:

•Minimum number of active links

•Multilink interleave

Note Minimum number active links must be configured at both endpoints.

SUMMARY STEPS

1. configure

2. interface multilink interface-path-id

3. multilink

4. ppp multilink minimum-active links value

5. multilink interleave

6. no shutdown

7. end
or
commit

DETAILED STEPS


	Command or Action	Purpose
Step 1	configure Example: RP/0/0/CPU0:router# configure	Enters global configuration mode.
Step 2	interface multilink interface-path-id Example: RP/0/0/CPU0:router(config)# interface multilink 0/1/0/0/1	Specifies the multilink interface name and instance identifier in rack/slot/module/port/bundle-id notation, and enters interface configuration mode.
Step 3	multilink Example: RP/0/0/CPU0:router(config-if)# multilink	Enters interface multilink configuration mode.
Step 4	ppp multilink minimum-active links value Example: RP/0/0/CPU0:router(config-if-multilink)# ppp multilink minimum-active links 12	(Optional) Specifies the minimum number of active links for the multilink interface. Note
Step 5	multilink interleave Example: RP/0/0/CPU0:router(config-if-multilink)# multilink interleave	(Optional) Enables interleave on a multilink interface.
Step 6	no shutdown Example: RP/0/0/CPU0:router(config-if-mutlilink)# no shutdown	Removes the shutdown configuration. •The removal of the shutdown configuration removes the forced administrative down on the controller, enabling the controller to move to an up or a down state.
Step 7	end or commit Example: RP/0/0/CPU0:router(config-t3)# end or RP/0/0/CPU0:router(config-t3)# commit	Saves configuration changes. •When you issue the end command, the system prompts you to commit changes: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: –Entering yes saves configuration changes to the running configuration file, exits the configuration session, and returns the router to EXEC mode. –Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. –Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. •Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session.

Configuration Examples for PPP

This section provides the following configuration examples:

•Configuring a POS Interface with PPP Encapsulation: Example

•Configuring a Serial Interface with PPP Encapsulation: Example

•Verifying Multilink PPP Configurations

Configuring a POS Interface with PPP Encapsulation: Example

The following example shows how to create and configure a POS interface with PPP encapsulation:

RP/0/0/CPU0:router# configure

RP/0/0/CPU0:router(config)# interface POS 0/3/0/0

RP/0/0/CPU0:router(config-if)# ipv4 address 172.18.189.38 255.255.255.224

RP/0/0/CPU0:router(config-if)# encapsulation ppp

RP/0/0/CPU0:router(config-if)# no shutdown

RP/0/0/CPU0:router(config-if)# ppp pap sent-username P1_TEST-8 password xxxx

RP/0/0/CPU0:router(config-if)# ppp authentication chap pap MIS-access

RP/0/0/CPU0:router(config-if)# ppp chap password encrypted xxxx

RP/0/0/CPU0:router(config-if)# end

Uncommitted changes found, commit them? [yes]: yes

The following example shows how to configure POS interface 0/3/0/1 to allow two additional retries after an initial authentication failure (for a total of three failed authentication attempts):

RP/0/0/CPU0:router# configure

RP/0/0/CPU0:router(config)# interface POS 0/3/0/1

RP/0/0/CPU0:router(config-if)# ppp max-bad-auth 3

Configuring a Serial Interface with PPP Encapsulation: Example

The following example shows how to create and configure a serial interface with PPP MS-CHAP encapsulation:

RP/0/0/CPU0:router# configure

RP/0/0/CPU0:router(config)# interface serial 0/3/0/0/0:0

RP/0/0/CPU0:router(config-if)# ipv4 address 172.18.189.38 255.255.255.224

RP/0/0/CPU0:router(config-if)# encapsulation ppp

RP/0/0/CPU0:router(config-if)# no shutdown

RP/0/0/CPU0:router(config-if)# ppp authentication ms-chap MIS-access

RP/0/0/CPU0:router(config-if)# ppp ms-chap password encrypted xxxx

RP/0/0/CPU0:router(config-if)# end

Uncommitted changes found, commit them? [yes]: yes

Configuring MLPPP: Example

RP/0/0/CPU0:router# configure

RP/0/0/CPU0:router(config)# controller t3 0/1/0/0/1

RP/0/0/CPU0:router# mode t1

RP/0/0/CPU0:router(config-t3)# clock source internal

RP/0/0/CPU0:router(config-t3)# exit

RP/0/0/CPU0:router(config)# controller t1 0/1/0/0/1/1

RP/0/0/CPU0:router(config-t1)# channel-group 0

RP/0/0/CPU0:router(config-t1-channel_group)# timeslots 1-24

RP/0/0/CPU0:router(config-t1-channel_group)# exit

RP/0/0/CPU0:router(config-t1)# exit

RP/0/0/CPU0:router(config)# controller mgmtmultilink 0/1/0/0

RP/0/0/CPU0:router(config-mgmtmultilink)# bundle 20

RP/0/0/CPU0:router(config-t3)# commit

RP/0/0/CPU0:router(config-t3)# exit

RP/0/0/CPU0:router(config)# interface multilink 0/1/0/0/20

RP/0/0/CPU0:router(config-if)# ipv4 address 80.170.0.1/24

RP/0/0/CPU0:router(config-if)# multilink fragment-size 128

RP/0/0/CPU0:router(config-if)# keepalive disable

RP/0/0/CPU0:router(config-if)# exit

RP/0/0/CPU0:router(config)# interface serial 0/1/0/0/1/1:0

RP/0/0/CPU0:router(config-if)# encapsulation ppp

RP/0/0/CPU0:router(config-if)# multilink group 20

RP/0/0/CPU0:router(config-t3)# commit

RP/0/0/CPU0:router(config-t3)# exit

RP/0/0/CPU0:router(config)# interface multilink 0/1/0/0/1

RP/0/0/CPU0:router(config-if)# multilink

RP/0/0/CPU0:router(config-if-multilink)# ppp multilink minimum-active links 10

RP/0/0/CPU0:router(config-if-multilink)# multilink interleave

RP/0/0/CPU0:router(config-if-mutlilink)# no shutdown

RP/0/0/CPU0:router(config-t3)# commit

Verifying Multilink PPP Configurations

Use the following show commands to verify and troubleshoot your multilink configurations:

•show multilink interfaces: Examples

•show ppp interfaces multilink: Example

•show ppp interface serial: Example

•show imds interface multilink: Example

show multilink interfaces: Examples

RP/0/0/CPU0:Router# show multilink interfaces Serial 0/4/3/1/10:0

Mon Sep 21 09:24:19.604 UTC

Serial0/4/3/1/10:0 is up, line protocol is up

      Encapsulation: PPP

      Multilink group id: 6

      Member status: ACTIVE

RP/0/0/CPU0:Router# show multilink interfaces Multilink 0/4/3/0/3

Mon Sep 21 09:17:12.131 UTC

Multilink0/4/3/0/3 is up, line protocol is up

  Fragmentation: disabled

  Interleave: disabled

  Encapsulation: PPP

  Member Links: 1 active, 1 inactive

    - Serial0/4/3/1/5:0 is up, line protocol is up

      Encapsulation: PPP

      Multilink group id: 3

      Member status: ACTIVE

    - Serial0/4/3/1/6:0 is administratively down, line protocol is administratively down

Encapsulation: PPP

      Multilink group id: 3

      Member status: INACTIVE : LCP has not been negotiated

  Fragmentation Statistics

  Input Fragmented packets 0            Input Fragmented bytes 0

  Output Fragmented packets 0           Output Fragmented bytes 0

  Input Unfragmented packets 0          Input Unfragmented bytes 0

  Output Unfragmented packets 0         Output Unfragmented bytes 0

  Input Reassembled packets 0           Input Reassembled bytes 0

RP/0/5/CPU0:Mav-IOX-Rahul#sho multilink interfaces Serial 0/4/3/1/10:0

Mon Sep 21 09:24:19.604 UTC

Serial0/4/3/1/10:0 is up, line protocol is up

      Encapsulation: PPP

      Multilink group id: 6

      Member status: ACTIVE

RP/0/0/CPU0:Router# show multilink interfaces

Mon Sep 21 09:15:10.679 UTC

Multilink0/4/3/0/1 is up, line protocol is up

  Fragmentation: disabled

  Interleave: disabled

  Encapsulation: FR

  Member Links: 1 active, 1 inactive

   - Serial0/4/3/1/2:0: INACTIVE : Down  (Member link idle)

   - Serial0/4/3/1/1:0: ACTIVE : Up

Multilink0/4/3/0/10 is up, line protocol is down

  Fragmentation: disabled

  Interleave: disabled

  Encapsulation: PPP

  Member Links: 0 active, 0 inactive

  Fragmentation Statistics

  Input Fragmented packets 0            Input Fragmented bytes 0

  Output Fragmented packets 0           Output Fragmented bytes 0

  Input Unfragmented packets 0          Input Unfragmented bytes 0

  Output Unfragmented packets 0         Output Unfragmented bytes 0

  Input Reassembled packets 0           Input Reassembled bytes 0

Multilink0/4/3/0/100 is administratively down, line protocol is administratively down

  Fragmentation: disabled

  Interleave: disabled

  Encapsulation: PPP

  Member Links: 0 active, 0 inactive

  Fragmentation Statistics

  Input Fragmented packets 0            Input Fragmented bytes 0

  Output Fragmented packets 0           Output Fragmented bytes 0

  Input Unfragmented packets 0          Input Unfragmented bytes 0

  Output Unfragmented packets 0         Output Unfragmented bytes 0

  Input Reassembled packets 0           Input Reassembled bytes 0

Multilink0/4/3/0/2 is up, line protocol is up

  Fragmentation: disabled

  Interleave: disabled

  Encapsulation: FR

  Member Links: 2 active, 0 inactive

   - Serial0/4/3/1/4:0: ACTIVE : Up

   - Serial0/4/3/1/3:0: ACTIVE : Up

Multilink0/4/3/0/3 is up, line protocol is up

  Fragmentation: disabled

  Interleave: disabled

  Encapsulation: PPP

  Member Links: 1 active, 1 inactive

   - Serial0/4/3/1/5:0: ACTIVE

   - Serial0/4/3/1/6:0: INACTIVE : LCP has not been negotiated

  Fragmentation Statistics

  Input Fragmented packets 0            Input Fragmented bytes 0

  Output Fragmented packets 0           Output Fragmented bytes 0

  Input Unfragmented packets 0          Input Unfragmented bytes 0

  Output Unfragmented packets 0         Output Unfragmented bytes 0

  Input Reassembled packets 0           Input Reassembled bytes 0

Multilink0/4/3/0/4 is up, line protocol is up

  Fragmentation: disabled

  Interleave: disabled

  Encapsulation: PPP

  Member Links: 2 active, 0 inactive

   - Serial0/4/3/1/8:0: ACTIVE

   - Serial0/4/3/1/7:0: ACTIVE

  Fragmentation Statistics

  Input Fragmented packets 0            Input Fragmented bytes 0

  Output Fragmented packets 0           Output Fragmented bytes 0

  Input Unfragmented packets 0          Input Unfragmented bytes 0

  Output Unfragmented packets 0         Output Unfragmented bytes 0

  Input Reassembled packets 0           Input Reassembled bytes 0

Multilink0/4/3/0/5 is up, line protocol is up

  Fragmentation: disabled

  Interleave: enabled

  Encapsulation: PPP

  Member Links: 1 active, 0 inactive

   - Serial0/4/3/1/9:0: ACTIVE

  Fragmentation Statistics

  Input Fragmented packets 0            Input Fragmented bytes 0

  Output Fragmented packets 0           Output Fragmented bytes 0

  Input Unfragmented packets 0          Input Unfragmented bytes 0

  Output Unfragmented packets 0         Output Unfragmented bytes 0

  Input Reassembled packets 0           Input Reassembled bytes 0

Multilink0/4/3/0/6 is up, line protocol is up

  Fragmentation: disabled

  Interleave: enabled

  Encapsulation: PPP

  Member Links: 1 active, 0 inactive

   - Serial0/4/3/1/10:0: ACTIVE

  Fragmentation Statistics

  Input Fragmented packets 0            Input Fragmented bytes 0

  Output Fragmented packets 0           Output Fragmented bytes 0

  Input Unfragmented packets 0          Input Unfragmented bytes 0

  Output Unfragmented packets 0         Output Unfragmented bytes 0

  Input Reassembled packets 0           Input Reassembled bytes 0

Multilink0/4/3/0/7 is up, line protocol is down

  Fragmentation: disabled

  Interleave: enabled

  Encapsulation: PPP

  Member Links: 0 active, 1 inactive

   - Serial0/4/3/1/11:0: INACTIVE : LCP has not been negotiated

  Fragmentation Statistics

  Input Fragmented packets 0            Input Fragmented bytes 0

  Output Fragmented packets 0           Output Fragmented bytes 0

  Input Unfragmented packets 0          Input Unfragmented bytes 0

  Output Unfragmented packets 0         Output Unfragmented bytes 0

  Input Reassembled packets 0           Input Reassembled bytes 0

Multilink0/4/3/0/8 is up, line protocol is down

  Fragmentation: disabled

  Interleave: enabled

  Encapsulation: PPP

  Member Links: 0 active, 1 inactive

   - Serial0/4/3/1/12:0: INACTIVE : LCP has not been negotiated

  Fragmentation Statistics

  Input Fragmented packets 0            Input Fragmented bytes 0

  Output Fragmented packets 0           Output Fragmented bytes 0

  Input Unfragmented packets 0          Input Unfragmented bytes 0

  Output Unfragmented packets 0         Output Unfragmented bytes 0

  Input Reassembled packets 0           Input Reassembled bytes 0

show ppp interfaces multilink: Example

RP/0/0/CPU0:Router# show ppp interfaces multilink 0/3/1/0/1

Multilink 0/3/1/0/1 is up, line protocol is up

LCP: Open

     Keepalives disabled

  IPCP: Open

     Local IPv4 address: 1.1.1.2

     Peer IPv4 address:  1.1.1.1

  Multilink

     Member Links: 2 active, 1 inactive (min-active 1)

      - Serial0/3/1/0/0:0: ACTIVE

      - Serial0/3/1/0/1:0: ACTIVE

      - Serial0/3/1/0/2:0: INACTIVE : LCP has not been negotiated

show ppp interface serial: Example

RP/0/0/CPU0:Router# show ppp interface Serial 0/3/1/0/0:0

Serial 0/3/1/0/0:0 is up, line protocol is up

  LCP: Open

     Keepalives disabled

     Local MRU: 1500 bytes

     Peer  MRU: 1500 bytes

     Local Bundle MRRU: 1596 bytes

     Peer  Bundle MRRU: 1500 bytes

     Local Endpoint Discriminator: 1b61950e3e9ce8172c8289df0000003900000001

     Peer  Endpoint Discriminator: 7d046cd8390a4519087aefb90000003900000001

  Authentication

     Of Peer: <None>

     Of Us:   <None>

  Multilink

     Multilink group id: 1

     Member status: ACTIVE

show imds interface multilink: Example

RP/0/0/CPU0:Router# show imds interface Multilink 0/3/1/0/1

IMDS INTERFACE DATA (Node 0x0)

Multilink0_3_1_0_1 (0x04001200)

-----------------------

flags: 0x0001002f    type: 55 (IFT_MULTILINK)    encap: 52 (ppp)

state: 3 (up)     mtu: 1600    protocol count: 3

control parent: 0x04000800     data parent: 0x00000000

       protocol         capsulation           state        mtu

    --------------- -------------------- --------------- --------

    12 (ipv4)

                    26 (ipv4)            3 (up)          1500

                    47 (ipcp)            3 (up)          1500

    16 (ppp_ctrl)

                    53 (ppp_ctrl)        3 (up)          1500

    0 (Unknown)

                    139 (c_shim)         3 (up)          1600

                    52 (ppp)             3 (up)          1504

                    56 (queue_fifo)      3 (up)          1600

                    60 (txm_nopull)      3 (up)          1600

Additional References

These sections provide references related to PPP encapsulation.

Related Topic	Document Title
Cisco IOS XR master command reference	Cisco IOS XR Master Commands List
Cisco IOS XR interface configuration commands	Cisco IOS XR Interface and Hardware Component Command Reference
Initial system bootup and configuration information for a router using Cisco IOS XR software	Cisco IOS XR Getting Started Guide
Cisco IOS XR AAA services configuration information	Cisco IOS XR System Security Configuration Guide and Cisco IOS XR System Security Command Reference

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 using Cisco IOS XR software, use the Cisco MIB Locator found at the following URL: http://www.cisco.com/go/mibs

RFCs


RFCs	Title
RFC-1661	The Point-to-Point Protocol (PPP)
RFC- 1994	PPP Challenge Handshake Authentication Protocol (CHAP)

Technical Assistance


Description	Link
The Cisco Technical Support website contains thousands of 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/support

Bias-Free Language

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Chapter: Configuring PPP on Cisco IOS XR Software

Configuring PPP on Cisco IOS XR Software

Contents

Prerequisites for Configuring PPP

Information About PPP

PPP Authentication

PAP Authentication

CHAP Authentication

MS-CHAP Authentication

Multilink PPP

MLPPP Feature Summary

IPHC Over MLPPP

T3 SONET Channels

How to Configure PPP

Modifying the Default PPP Configuration

Prerequisites

SUMMARY STEPS

DETAILED STEPS

Configuring PPP Authentication

Enabling PAP, CHAP, and MS-CHAP Authentication

Prerequisites

SUMMARY STEPS

DETAILED STEPS

Where To Go Next

Configuring a PAP Authentication Password

Prerequisites

SUMMARY STEPS

DETAILED STEPS

Configuring a CHAP Authentication Password

Prerequisites

Restrictions

SUMMARY STEPS

DETAILED STEPS

Configuring an MS-CHAP Authentication Password

Prerequisites

Restrictions

SUMMARY STEPS

DETAILED STEPS

Disabling an Authentication Protocol

Disabling PAP Authentication on an Interface

SUMMARY STEPS

DETAILED STEPS

Disabling CHAP Authentication on an Interface

SUMMARY STEPS

DETAILED STEPS

Disabling MS-CHAP Authentication on an Interface

SUMMARY STEPS

DETAILED STEPS

Configuring Multilink PPP

Prerequisites

Restrictions

Configuring the Controller

SUMMARY STEPS

DETAILED STEPS

Configuring the Interfaces

Restrictions

SUMMARY STEPS

DETAILED STEPS

Configuring MLPPP Optional Features

SUMMARY STEPS

DETAILED STEPS

Configuration Examples for PPP

Configuring a POS Interface with PPP Encapsulation: Example

Configuring a Serial Interface with PPP Encapsulation: Example

Configuring MLPPP: Example

Verifying Multilink PPP Configurations

show multilink interfaces: Examples

show ppp interfaces multilink: Example

show ppp interface serial: Example

show imds interface multilink: Example

Additional References

Related Documents

Standards

MIBs

RFCs

Technical Assistance

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