PPP Commands on the Cisco IOS XR Software

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Updated:April 29, 2011

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PPP Commands on the Cisco IOS XR Software

PPP Commands on the Cisco IOS XR Software

This module provides command line interface (CLI) commands for configuring Point-to-Point Protocol (PPP) on the Cisco XR 12000 Series Router.

Point-to-Point Protocol (PPP) is an encapsulation scheme that can be used on Packet-over-SONET (POS), serial, and multilink interfaces. PPP is a standard protocol used to send data over synchronous serial links. PPP also provides a Link Control Protocol (LCP) for negotiating properties of the link. LCP uses echo requests and responses to monitor the continuing availability of the link.

PPP provides the following Network Control Protocols (NCPs) for negotiating properties of data protocols that will run on the link:


  • Cisco Discovery Protocol Control Protocol (CDPCP) to negotiate CDP properties
  • IP Control Protocol (IPCP) to negotiate IP properties
  • IP Version 6 Control Protocol (IPv6CP) to negotiate IPv6 properties
  • Multiprotocol Label Switching Control Protocol (MPLSCP) to negotiate MPLS properties
  • Open System Interconnection Control Protocol (OSICP) to negotiate OSI properties

encapsulation ppp

To enable encapsulation for communication with routers or bridges using the Point-to-Point Protocol (PPP), use the encapsulation ppp command in interface configuration mode. To disable PPP encapsulation, use the no form of this command.

encapsulation ppp

no encapsulation ppp

Syntax Description

This command has no arguments or keywords.

Command Default

PPP encapsulation is disabled.

Command Modes

Interface configuration

Command History

Release

Modification

Release 3.2

This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes the proper task IDs. If you suspect user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Use the encapsulation ppp command to enable PPP encapsulation on an interface.

Task ID

Task ID

Operations

ppp

read, write

interface

read, write

Examples

The following example shows how to set up PPP encapsulation on interface POS 0/1/0/1: 

RP/0/0/CPU0:router# configure
RP/0/0/CPU0:router(config)# interface POS 0/1/0/1
RP/0/0/CPU0:router(config-if)# encapsulation ppp

The following example shows how to set up PPP encapsulation on a serial interface: 

RP/0/0/CPU0:router# configure
RP/0/0/CPU0:router# interface serial 0/0/1/2/4:3
RP/0/0/CPU0:router# encapsulation ppp

Related Commands

Command

Description

show ppp interfaces

Displays PPP state information for an interface.  

ppp authentication

To enable Challenge Handshake Authentication Protocol (CHAP), MS-CHAP, or Password Authentication Protocol (PAP), and to specify the order in which CHAP, MS-CHAP, and PAP authentication is selected on the interface, use the ppp authentication command in interface configuration mode. To disable PPP authentication, use the no form of this command.

ppp authentication protocol [ protocol [protocol] ] { list-name | default }

no ppp authentication

Syntax Description

protocol

Name of the authentication protocol used for PPP authentication. See Table 1 for the appropriate keyword. You may select one, two, or all three protocols, in any order.

list-name

(Optional) Used with authentication, authorization, and accounting (AAA). Name of a list of methods of authentication to use. If no list name is specified, the system uses the default. The list is created with the aaa authentication ppp command.

default

(Optional) Specifies the name of the list of methods created with the aaa authentication ppp command.

Command Default

PPP authentication is not enabled.

Command Modes

Interface configuration

Command History

Release

Modification

Release 3.2

This command was introduced.

Release 3.2

This command was corrected to include the possibility of specifying three protocols simultaneously.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes the proper task IDs. If you suspect user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

When you enable CHAP or PAP authentication (or both), the local router requires the remote device to prove its identity before allowing data traffic to flow. PAP authentication requires the remote device to send a name and a password, which is checked against a matching entry in the local username database or in the remote security server database. CHAP authentication sends a challenge message to the remote device. The remote device encrypts the challenge value with a shared secret and returns the encrypted value and its name to the local router in a response message. The local router attempts to match the remote device’s name with an associated secret stored in the local username or remote security server database; it uses the stored secret to encrypt the original challenge and verify that the encrypted values match.

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.


Note

If you use a list-name value that was not configured with the aaa authentication ppp command, then authentication does not complete successfully and the line does not come up.

Table 1 lists the protocols used to negotiate PPP authentication.

Table 1 PPP Authentication Protocols for Negotiation

Protocol

Description

chap

Enables CHAP on an interface.

ms-chap

Enables Microsoft’s version of CHAP (MS-CHAP) on an interface.

pap

Enables PAP on an interface.

Enabling or disabling PPP authentication does not affect the ability of the local router to authenticate itself to the remote device.

MS-CHAP is the Microsoft version of CHAP. Like the standard version of CHAP, MS-CHAP is used for PPP authentication. In this case, authentication occurs between a personal computer using Microsoft Windows NT or Microsoft Windows 95 and a Cisco router or access server acting as a network access server.

Enabling or disabling PPP authentication does not affect the local router authenticating itself to the remote device.

Task ID

Task ID

Operations

ppp

read, write

aaa

read, write

Examples

In the following example, CHAP is enabled on POS 0/4/0/1 and uses the authentication list MIS-access:

RP/0/0/CPU0:router# configure
RP/0/0/CPU0:router(config)# interface POS 0/4/0/1
RP/0/0/CPU0:router(config-if)# encapsulation ppp
RP/0/0/CPU0:router(config-if)# ppp authentication chap MIS-access

Related Commands

Command

Description

aaa authentication ppp

Specifies one or more AAA authentication methods for use on serial interfaces running PPP.

encapsulation

Sets the encapsulation method used by the interface.

username

Configures a new user with a username, establishes a password, and grants permissions for the user.

ppp chap password

To enable a router calling a collection of routers to configure a common Challenge Handshake Authentication Protocol (CHAP) secret password, use the ppp chap password command in interface configuration mode. To disable the password, use the no form of this command.

ppp chap password [ clear | encrypted ] password

no ppp chap password [ clear | encrypted ] password

Syntax Description

clear

(Optional) Specifies the cleartext encryption parameter for the password.

encrypted

(Optional) Indicates that the password is already encrypted.

password

Cleartext or already-encrypted password.

Command Default

The password is disabled.

Command Modes

Interface configuration

Command History

Release

Modification

Release 3.2

This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes the proper task IDs. If you suspect user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

The ppp chap password command is sent in CHAP responses and is used by the peer to authenticate the local router. This does not affect local authentication of the peer. This command is useful for routers that do not support this command (such as routers running older Cisco IOS XR images).

The CHAP secret password is used by the routers in response to challenges from an unknown peer.

Task ID

Task ID

Operations

ppp

read, write

aaa

read, write

Examples

In the following example, a password (xxxx) is entered as a cleartext password: 

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

When the password is displayed (as shown in the following example, using the show running-config command), the password xxxx appears as 030752180500:

RP/0/0/CPU0:router(config)# show running-config interface POS 1/0/1/0

interface POS0/1/4/2

description Connected to P1_CRS-8 POS 0/1/4/3
ipv4 address 10.12.32.2 255.255.255.0
encapsulation ppp
ppp authentication chap pap
ppp chap password encrypted 030752180500

On subsequent logins, entering any of the three following commands would have the same effect of making xxxx the password for remote CHAP authentication:

RP/0/0/CPU0:router# configure
RP/0/0/CPU0:router(config)# interface POS 1/0/1/0
RP/0/0/CPU0:router(config-if)# ppp chap password xxxx
RP/0/0/CPU0:router(config-if)# ppp chap password clear xxxx
RP/0/0/CPU0:router(config-if)# ppp chap password encrypted 1514190900

Related Commands

Command

Description

aaa authentication ppp

Specifies one or more authentication, authorization, and accounting (AAA) methods for use on serial interfaces running PPP.

ppp authentication

Enables CHAP, MS-CHAP, or PAP, and specifies the order in which CHAP, MS-CHAP, and PAP authentication is selected on the interface.

ppp chap refuse

Refuses CHAP authentication from peers requesting it.

ppp max-bad-auth

Configures a PPP interface not to reset itself immediately after an authentication failure but instead to allow a specified number of authentication retries.

show running-config

Displays the contents of the currently running configuration file or the configuration for a specific interface, or map class information.

ppp chap refuse

To refuse Challenge Handshake Authentication Protocol (CHAP) authentication from peers requesting it, use the ppp chap refuse command in interface configuration mode. To allow CHAP authentication, use the no form of this command.

ppp chap refuse

no ppp chap refuse

Syntax Description

This command has no arguments or keywords.

Command Default

CHAP authentication is disabled.

Command Modes

Interface configuration

Command History

Release

Modification

Release 3.2

This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes the proper task IDs. If you suspect user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

The ppp chap refuse command specifies that CHAP authentication is disabled for all calls, meaning that all attempts by the peer to force the user to authenticate using CHAP are refused.

If outbound Password Authentication Protocol (PAP) has been configured (using the ppp authentication command), PAP is suggested as the authentication method in the refusal packet.

Task ID

Task ID

Operations

ppp

read, write

aaa

read, write

Examples

The following example shows how to specify POS interface 0/3/0/1 and disable CHAP authentication from occurring if a peer calls in requesting CHAP authentication. The method of encapsulation on the interface is PPP. 

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

Related Commands

Command

Description

aaa authentication ppp

Specifies one or more authentication, authorization, and accounting (AAA) methods for use on serial interfaces running PPP.

ppp authentication

Enables CHAP, MS-CHAP, or PAP, and specifies the order in which CHAP, MS-CHAP, and PAP authentication is selected on the interface.

ppp max-bad-auth

Configures a PPP interface not to reset itself immediately after an authentication failure but instead to allow a specified number of authentication retries.

ppp pap sent-username password

Enables remote PAP support for an interface, and includes the sent-username and password commands in the PAP authentication request packet to the peer.

ppp max-bad-auth

To configure a PPP interface not to reset itself immediately after an authentication failure but instead to allow a specified number of authentication retries, use the ppp max-bad-auth command in interface configuration mode. To reset to the default of immediate reset, use the no form of this command.

ppp max-bad-auth retries

no ppp max-bad-auth

Syntax Description

retries

Number of retries after which the interface is to reset itself. Range is from 0 to 10. Default is 0 retries.

Command Default

retries: 0

Command Modes

Interface configuration

Command History

Release

Modification

Release 3.2

This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes the proper task IDs. If you suspect user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

The ppp max-bad-auth command applies to any interface on which PPP encapsulation is enabled.

Task ID

Task ID

Operations

ppp

read, write

aaa

read, write

Examples

In the following example, POS interface 0/3/0/1 is set 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)# encapsulation ppp
RP/0/0/CPU0:router(config-if)# ppp authentication chap
RP/0/0/CPU0:router(config-if)# ppp max-bad-auth 3

ppp max-configure

To specify the maximum number of configure requests to attempt (without response) before stopping the requests, use the ppp max-configure command in interface configuration mode. To disable the maximum number of configure requests and return to the default, use the no form of this command.

ppp max-configure retries

no ppp max-configure

Syntax Description

retries

Maximum number of retries. Range is 4 through 20. Default is 10.

Command Default

retries: 10

Command Modes

Interface configuration

Command History

Release

Modification

Release 3.2

This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes the proper task IDs. If you suspect user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Use the ppp max-configure command to specify how many times an attempt is made to establish a Link Control Protocol (LCP) session between two peers for a particular interface. If a configure request message receives a reply before the maximum number of configure requests are sent, further configure requests are abandoned.

Task ID

Task ID

Operations

ppp

read, write

Examples

In the following example, a limit of four configure requests is specified:

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)# encapsulation ppp
RP/0/0/CPU0:router(config-if)# ppp max-configure 4

Related Commands

Command

Description

encapsulation ppp

Enables encapsulation for communication with routers or bridges using PPP.  

ppp max-failure

Configures the maximum number of consecutive CONFNAKs to permit before terminating a negotiation.  

ppp max-terminate

Configures the maximum number of terminate requests to send without reply before closing down the LCP or NCP.  

ppp max-failure

To configure the maximum number of consecutive Configure Negative Acknowledgments (CONFNAKs) to permit before terminating a negotiation, use the ppp max-failure command in interface configuration mode. To disable the maximum number of CONFNAKs and return to the default, use the no form of this command.

ppp max-failure retries

no ppp max-failure

Syntax Description

retries

Maximum number of CONFNAKs to permit before terminating a negotiation. Range is from 2 to 10. Default is 5.

Command Default

retries: 5

Command Modes

Interface configuration

Command History

Release

Modification

Release 3.2

This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes the proper task IDs. If you suspect user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Task ID

Task ID

Operations

ppp

read, write

Examples

The following ppp max-failure command specifies that no more than three CONFNAKs are permitted before terminating the negotiation: 

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)# encapsulation ppp
RP/0/0/CPU0:router(config-if)# ppp max-failure 3

Related Commands

Command

Description

encapsulation ppp

Enables encapsulation for communication with routers or bridges using PPP.  

ppp max-configure

Specifies the maximum number of configure requests to attempt (without response) before stopping the requests.  

ppp max-terminate

Configures the maximum number of terminate requests to send without reply before closing down the LCP or NCP.  

ppp max-terminate

To configure the maximum number of terminate requests (TermReqs) to send without reply before closing down the Link Control Protocol (LCP) or Network Control Protocol (NCP), use the ppp max-terminate command in interface configuration mode. To disable the maximum number of TermReqs and return to the default, use the no form of this command.

ppp max-terminate number

no ppp max-terminate

Syntax Description

number

Maximum number of TermReqs to send without reply before closing down the LCP or NCP. Range is from 2 to 10. Default is 2.

Command Default

number: 2

Command Modes

Interface configuration

Command History

Release

Modification

Release 3.2

This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes the proper task IDs. If you suspect user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Task ID

Task ID

Operations

ppp

read, write

Examples

In the following example, a maximum of five TermReqs are specified to be sent before terminating and closing LCP or NCP:

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)# encapsulation ppp
RP/0/0/CPU0:router(config-if)# ppp max-terminate 5

Related Commands

Command

Description

ppp max-configure

Specifies the maximum number of configure requests to attempt (without response) before stopping the requests.  

ppp max-failure

Configures the maximum number of consecutive CONFNAKs to permit before terminating a negotiation.  

ppp ms-chap password

To configure a common Microsoft Challenge Handshake Authentication (MS-CHAP) secret password, use the ppp ms-chap password command in interface configuration mode. To disable the password, use the no form of this command.

ppp ms-chap password [ clear | encrypted ] password

no ppp ms-chap password [ clear | encrypted ] password

Syntax Description

clear

(Optional) Specifies the cleartext encryption parameter for the password.

encrypted

(Optional) Indicates that the password is already encrypted.

password

Cleartext or already-encrypted password.

Command Default

The password is disabled.

Command Modes

Interface configuration

Command History

Release

Modification

Release 3.3.0

This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes the proper task IDs. If you suspect user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

The ppp ms-chap password command is sent in CHAP responses and is used by the peer to authenticate the local router. This does not affect local authentication of the peer. The ppp ms-chap password command is useful for routers that do not support this command (such as routers running older software images).

The MS-CHAP secret password is used by the routers in response to challenges from an unknown peer.

Task ID

Task ID

Operations

ppp

read, write

Examples

The following example shows how to enter a password (xxxx) as a cleartext password: 

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

ppp ms-chap refuse

To refuse Microsoft Challenge Handshake Authentication Protocol (MS-CHAP) authentication from peers requesting it, use the ppp ms-chap refuse command in interface configuration mode. To allow MS-CHAP authentication, use the no form of this command.

ppp ms-chap refuse

no ppp ms-chap refuse

Syntax Description

This command has no arguments or keywords.

Command Default

MS-CHAP authentication is disabled.

Command Modes

Interface configuration

Command History

Release

Modification

Release 3.3.0

This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes the proper task IDs. If you suspect user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

The ppp ms-chap refuse command specifies that MS-CHAP authentication is disabled for all calls, meaning that all attempts by the peer to force the user to authenticate using MS-CHAP are refused.

If outbound Password Authentication Protocol (PAP) has been configured (using the ppp authentication command), PAP is suggested as the authentication method in the refusal packet.

Task ID

Task ID

Operations

ppp

read, write

Examples

The following example shows how to specify POS interface 0/3/0/1 and disable MS-CHAP authentication from occurring if a peer calls in requesting MS-CHAP authentication. The method of encapsulation on the interface is PPP. 

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

Related Commands

Command

Description

ppp authentication

Enables CHAP, MS-CHAP, or PAP, and specifies the order in which CHAP, MS-CHAP, and PAP authentication is selected on the interface.  

ppp pap refuse

To refuse Password Authentication Protocol (PAP) authentication from peers requesting it, use the ppp pap refuse command in interface configuration mode. To allow PAP authentication, use the no form of this command.

ppp pap refuse

no ppp pap refuse

Syntax Description

This command has no arguments or keywords.

Command Default

PAP authentication is disabled.

Command Modes

Interface configuration

Command History

Release

Modification

Release 3.2

This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes the proper task IDs. If you suspect user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

The ppp pap refuse command specifies that PAP authentication is disabled for all calls, meaning that all attempts by the peer to force the user to authenticate using PAP are refused.

If outbound Challenge Handshake Authentication Protocol (CHAP) has been configured (using the ppp authentication command), CHAP is suggested as the authentication method in the refusal packet.

Task ID

Task ID

Operations

ppp

read, write

aaa

read, write

Examples

The following example shows how to specify POS 0/3/0/1 using PPP encapsulation on the interface. This example shows PAP authentication being specified as disabled if a peer calls in requesting PAP authentication.

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

Related Commands

Command

Description

aaa authentication ppp

Specifies one or more authentication, authorization, and accounting (AAA) methods for use on serial interfaces running PPP.

ppp authentication

Enables CHAP, MS-CHAP, or PAP, and specifies the order in which CHAP, MS-CHAP, and PAP authentication is selected on the interface.

ppp max-bad-auth

Configures a PPP interface not to reset itself immediately after an authentication failure but instead to allow a specified number of authentication retries.

ppp pap sent-username password

Enables remote PAP support for an interface, and includes the sent-username and password commands in the PAP authentication request packet to the peer.

ppp pap sent-username password

To enable remote Password Authentication Protocol (PAP) support for an interface, and to use the values specified for username and password in the PAP authentication request, use the ppp pap sent-username password command in interface configuration mode. To disable remote PAP support, use the no form of this command.

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

no ppp pap sent-username username password [ clear | encrypted ] password

Syntax Description

username

Username sent in the PAP authentication request.

clear

(Optional) Specifies the cleartext encryption parameter for the password.

encrypted

(Optional) Indicates that the password is already encrypted.

password

Cleartext or already-encrypted password.

Command Default

Remote PAP support is disabled.

Command Modes

Interface configuration

Command History

Release

Modification

Release 3.2

This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes the proper task IDs. If you suspect user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Use the ppp pap sent-username password command to enable remote PAP support (for example, to respond to the peer’s request to authenticate with PAP) and to specify the parameters to be used when sending the PAP authentication request.

You must configure the ppp pap sent-username password command for each interface.

Task ID

Task ID

Operations

ppp

read, write

aaa

read, write

Examples

In the following example, a password is entered as a cleartext password, xxxx: 

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

When the password is displayed (as shown in the following example, using the show running-config command), the password notified appears as 05080F1C2243:

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

interface POS0/1/0/0
description Connected to P1_CRS-8 POS 0/1/4/2
 ipv4 address 10.12.32.2 255.255.255.0
 encapsulation ppp
 ppp pap sent-username P2_CRS-8 password encrypted 05080F1C2243

On subsequent logins, entering any of the three following commands would have the same effect of making xxxx the password for remote PAP authentication:

RP/0/0/CPU0:router# configure
RP/0/0/CPU0:router(config)# interface POS 0/1/0/0
RP/0/0/CPU0:router(config-if)# ppp pap sent-username xxxx password notified
RP/0/0/CPU0:router(config-if)# ppp pap sent-username xxxx password clear notified
RP/0/0/CPU0:router(config-if)# ppp pap sent-username xxxx encrypted 1514190900

Related Commands

Command

Description

aaa authentication ppp

Specifies one or more authentication, authorization, and accounting (AAA) methods for use on serial interfaces running PPP.

ppp authentication

Enables CHAP, MS-CHAP, or PAP, and specifies the order in which CHAP, MS-CHAP, and PAP authentication is selected on the interface.

ppp multilink multiclass

Refuses PAP authentication from peers requesting it

ppp timeout authentication

Sets PPP authentication timeout parameters.

show running-config

Displays the contents of the currently running configuration file or the configuration for a specific interface, or map class information.

ppp timeout authentication

To set PPP authentication timeout parameters, use the ppp timeout authentication command in interface configuration mode. To reset the default value, use the no form of this command.

ppp timeout authentication seconds

no ppp timeout authentication

Syntax Description

seconds

Maximum time, in seconds, to wait for a response to an authentication packet. Range is from 3 to 30 seconds. Default is 10 seconds.

Command Default

seconds: 10

Command Modes

Interface configuration

Command History

Release

Modification

Release 3.2

This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes the proper task IDs. If you suspect user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

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.


Note

The timeout affects connection times only if packets are lost.

Note

Although lowering the authentication timeout is beneficial if packets are lost, sending authentication requests faster than the peer can handle them results in churn and a slower connection time.

Task ID

Task ID

Operations

ppp

read, write

Examples

In the following example, PPP timeout authentication is set to 20 seconds:

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)# encapsulation ppp
RP/0/0/CPU0:router(config-if)# ppp timeout authentication 20

Related Commands

Command

Description

aaa authentication ppp

Specifies one or more authentication, authorization, and accounting (AAA) methods for use on serial interfaces running PPP.

ppp authentication

Enables CHAP, MS-CHAP, or PAP, and specifies the order in which CHAP, MS-CHAP, and PAP authentication is selected on the interface.

ppp timeout retry

To set PPP timeout retry parameters, use the ppp timeout retry command in interface configuration mode. To reset the time value, use the no form of this command.

ppp timeout retry seconds

no ppp timeout retry

Syntax Description

seconds

Maximum time, in seconds, to wait for a response during PPP negotiation. Range is from 1 to 10 seconds. Default is 3 seconds.

Command Default

seconds: 3

Command Modes

Interface configuration

Command History

Release

Modification

Release 3.2

This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes the proper task IDs. If you suspect user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

The ppp timeout retry command is useful for setting a maximum amount of time PPP should wait for a response to any control packet it sends.

Task ID

Task ID

Operations

ppp

read, write

Examples

The following example shows the retry timer being set to 8 seconds: 

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)# encapsulation ppp
RP/0/0/CPU0:router(config-if)# ppp timeout retry 8

show ppp interfaces

To display PPP state information for an interface, use the show ppp interfaces command in EXEC mode.

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

Syntax Description

brief

(Optional) Displays brief output for all interfaces on the router, for a specific POS interface instance, or for all interfaces on a specific node.

detail

(Optional) Displays detailed output for all interfaces on the router, for a specific interface instance, or for all interfaces on a specific node.

type

Interface type. For more information, use the question mark (?) online help function.

interface-path-id

Physical interface or virtual interface.

Note   

Use the show interfaces command to see a list of all interfaces currently configured on the router.

For more information about the syntax for the router, use the question mark (?) online help function.

all

(Optional) Displays detailed PPP information for all nodes.

location node-id

(Optional) Displays detailed PPP information for the designated node. The node-id argument is entered in the rack/slot/module notation.

Command Default

No default behavior or values

Command Modes

EXEC

Command History

Release

Modification

Release 3.2

This command introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes the proper task IDs. If you suspect user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

There are seven possible PPP states applicable for either the Link Control Protocol (LCP) or the Network Control Protocol (NCP).

The command output displays a summary of the interface as it is in the PPP Interface Descriptor Block (IDB). The output includes the following information (where applicable):


  • Interface state
  • Line protocol state
  • Link Control Protocol (LCP) state
  • Network Control Protocol (NCP) state
  • Multilink PPP state
  • Multilink PPP configuration
  • Keepalive configuration
  • Authentication configuration
  • Negotiated MRUs
  • Negotiated IP addresses

This command can display information for a single interface, all interfaces on a specified node, or all interfaces on the router.

Task ID

Task ID

Operations

ppp

read

Examples

The following example shows how to display PPP state information for a POS interface: 

RP/0/0/CPU0:router# show ppp interface POS 0/2/0/3

    POS0/2/0/3 is up, line protocol is up
      LCP: Open
         Keepalives enabled (10 sec)
         Local MRU: 4470 bytes
         Peer  MRU: 4470 bytes
      Authentication
         Of Us:    CHAP (Completed as 'test-user')
         Of Peer:  PAP (Completed as 'peer-user')
      CDPCP: Listen
      IPCP: Open
         Local IPv4 address: 55.0.0.1
         Peer IPv4 address:  55.0.0.2
         Peer DNS Primary:   55.0.0.254
         Peer DNS Secondary: 155.0.0.254
      IPV6CP: Open
         Local IPv6 address: fe80::3531:35ff:fe55:5747/128
         Peer IPv6 address:  fe80::3531:35ff:fe55:4213/128
      MPLSCP: Stopped

The following example shows how to display PPP state information for a POS interface that is running as a Layer 2 attachment circuit: 

RP/0/0/CPU0:# show ppp interface POS0/2/0/2

    POS0/2/0/2 is up, line protocol is up
      LCP: Open
         Running as L2 AC

The following example shows how to display PPP state information for a multilink interface: 

RP/0/0/CPU0:router:# show ppp interface Multilink 0/3/0/0/100

    Multilink0/3/0/0/100 is up, line protocol is down
      LCP: Open
         SSO-State: Standby-Up
         Keepalives disabled
      IPCP: Open
         SSO-State: Standby-Up
         Local IPv4 address: 100.0.0.1
         Peer IPv4 address:  100.0.0.2
      IPV6CP: Open
         Local IPv6 address: fe80::3531:35ff:fe55:4600/128
         Peer IPv6 address:  fe80::3531:35ff:fe55:3215/128
      Multilink
         Local MRRU: 1500 bytes
         Peer MRRU:  1500 bytes
         Local Endpoint Discriminator: 1234567812345678
         Peer Endpoint Discriminator:  1111222233334444
         MCMP classes: Local 4, Remote 2
         Member links: 2 active, 6 inactive (min-active 2)
           - Serial0/3/1/3/1  ACTIVE
           - Serial0/3/1/3/2  ACTIVE
           - Serial0/3/1/3/3  INACTIVE : LCP not negotiated
           - Serial0/3/1/3/4  INACTIVE : Mismatching peer endpoint
           - Serial0/3/1/3/5  INACTIVE : Mismatching peer auth name
           - Serial0/3/1/3/6  INACTIVE : MRRU option rejected by Peer
           - Serial0/3/1/3/7  INACTIVE : Mismatching local MCMP classes
           - Serial0/3/1/3/8  INACTIVE : MCMP option rejected by peer

The following example shows how to display PPP state information for a serial interface: 

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

    Serial0/3/1/3/1 is down, line protocol is down
      LCP: Open
         SSO-State: Standby-Up
         Keepalives enabled (10 sec)
         Local MRU: 1500 bytes
         Peer MRU:  1500 bytes
         Local Bundle MRRU: 1500 bytes
         Peer Bundle MRRU:  1500 bytes
         Local Endpoint Discriminator: 1234567812345678
         Peer Endpoint Discriminator:  1111222233334444
         Local MCMP Classes:  Not negotiated
         Remote MCMP Classes: Not negotiated
      Authentication
         Of Us:    CHAP (Completed as 'test-user')
         Of Peer:  PAP (Completed as 'peer-user')
      Multilink
         Multilink group id: 100
         Member status: ACTIVE
Table 2 show ppp interfaces Field Descriptions

Field

Description

Ack-Rcvd

Configuration acknowledgemt was received; waiting for peer to send configuration request.

Ack-Sent

Configuration acknowledgemt was sent; waiting for peer to respond to configuration request.

Authentication

Type of user authentication configured on the local equipment and on the peer equipment. Possible PPP authentication protocols are Challenge Handshake Authentication Protocol (CHAP), MS-CHAP, and Password Authentication Protocol (PAP).

Closed

Lower layer is up, but this layer is not required.

Closing

Shutting down due to local change.

Initial

Connection is idle.

IPCP

IP Control Protocol (IPCP) state. The seven possible states that may be displayed are as follows:


  • Initial—Lower layer is unavailable (Down), and no Open has occurred. The Restart timer is not running in the Initial state.
  • Starting—An administrative Open has been initiated, but the lower layer is still unavailable (Down). The Restart timer is not running in the Starting state. When the lower layer becomes available (Up), a Configure-Request is sent.
  • Closed— IPCP is not currently trying to negotiate.
  • Stopped—A Terminate-Request has been sent and the Restart timer is running, but a Terminate-Ack has not yet been received.
  • Closing—A Terminate-Request has been sent and the Restart timer is running, but a Terminate-Ack has not yet been received. Upon reception of a Terminate-Ack, the Closed state is entered. Upon the expiration of the Restart timer, a new Terminate-Request is transmitted, and the Restart timer is restarted. After the Restart timer has expired Max-Terminate times, the Closed state is entered.
  • Stopping—A Terminate-Request has been sent and the Restart timer is running, but a IPCP-Ack has not yet been received. Req-Sent.
  • ACKsent—IPCP has received a request and has replied to it.
  • ACKrcvd—IPCP has received a reply to a request it sent.
  • Open—IPCP is functioning properly.

Keepalive

Keepalive setting and interval in seconds for echo request packets.

LCP

Indicates the current state of LCP. The state of the LCP will report the following states:


  • Initial—Lower layer is unavailable (Down), and no Open has occurred. The Restart timer is not running in the Initial state.
  • Starting—An administrative Open has been initiated, but the lower layer is still unavailable (Down). The Restart timer is not running in the Starting state. When the lower layer becomes available (Up), a Configure-Request is sent.
  • Closed— LCP is not currently trying to negotiate.
  • Stopped—A Terminate-Request has been sent and the Restart timer is running, but a Terminate-Ack has not yet been received.
  • Closing—A Terminate-Request has been sent and the Restart timer is running, but a Terminate-Ack has not yet been received. Upon reception of a Terminate-Ack, the Closed state is entered. Upon the expiration of the Restart timer, a new Terminate-Request is transmitted, and the Restart timer is restarted. After the Restart timer has expired Max-Terminate times, the Closed state is entered.
  • Stopping—A Terminate-Request has been sent and the Restart timer is running, but a Terminate-Ack has not yet been received. Req-Sent.
  • ACKsent—LCP has received a request and has replied to it.
  • ACKrcvd—LCP has received a reply to a request it sent.
  • Open—LCP is functioning properly

Local IPv4 address

IPv4 address for the local interface.

Local MRU

Maximum receive unit. The maximum size of the information transported, in bytes, in the PPP packet received by the local equipment.

Open

Connection open.

OSICP

Open System Interconnection Control Protocol (OSICP) state. The possible states that may be displayed are as follows:


  • Initial—Lower layer is unavailable (Down), and no Open has occurred. The Restart timer is not running in the Initial state.
  • Starting—An administrative Open has been initiated, but the lower layer is still unavailable (Down). The Restart timer is not running in the Starting state. When the lower layer becomes available (Up), a Configure-Request is sent.
  • Closed— OSICP is not currently trying to negotiate.
  • Stopped—A Terminate-Request has been sent and the Restart timer is running, but a Terminate-Ack has not yet been received.
  • Closing—A Terminate-Request has been sent and the Restart timer is running, but a Terminate-Ack has not yet been received. Upon reception of a Terminate-Ack, the Closed state is entered. Upon the expiration of the Restart timer, a new Terminate-Request is transmitted, and the Restart timer is restarted. After the Restart timer has expired Max-Terminate times, the Closed state is entered.
  • Stopping—A Terminate-Request has been sent and the Restart timer is running, but a Terminate-Ack has not yet been received. Req-Sent.
  • ACKsent—OSICP has received a request and has replied to it.
  • ACKrcvd—OSICP has received a reply to a request it sent.
  • Open—OSICP is functioning properly.

Peer IPv4 address

IPv4 address for the peer equipment.

Peer MRU

Maximum receive unit. The maximum size of the information transported, in bytes, in the PPP packet received by the peer equipment.

Req-Sent

Configuration request was sent; waiting for peer to respond.

Starting

This layer is required, but lower layer is down.

Stopped

Listening for a configuration request.

Stopping

Shutting down as a result of interactions with peer.

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