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Point-to-Point Protocol (PPP)

Multichassis Multilink PPP with AS5300 Access Servers

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Document ID: 9578


Contents

Introduction
Prerequisites
      Requirements
      Components Used
      Conventions
Configure
      Network Diagram
      Configurations
Verify
Troubleshoot
      Troubleshooting Procedure
Related Information

Introduction

This document provides a sample configuration to configure multichassis multilink point-to-point protocol (PPP) with AS5300 Access Servers.

Prerequisites

Requirements

Ensure that you have these details before you attempt this configuration:

  • The Primary Rate Interface (PRI) switch type.

  • The IP addressing scheme.

  • Usernames and passwords.

Components Used

The information in this document is based on the AS5300 Access Server.

The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, make sure that you understand the potential impact of any command.

Conventions

Refer to Cisco Technical Tips Conventions for more information on document conventions.

Configure

In this configuration, the user places an ISDN call and brings up B channel 1. The call goes through the cloud and connects to one of the AS5300s in the stack group. AS5300-A accepts the call and then checks to see if another member of the stack group (in this case, the other AS5300) owns a call by this user. If the other members do not claim ownership, AS5300-A takes ownership of the call.

The second call comes in, and AS5300-B accepts the call. AS5300-B checks to see if any other members of the group own the call. AS5300-B finds that AS5300-A is the owner, and forms a Layer 2 tunnel to the AS5300-A to pass the call information and data between the connecting port and the owner of the call.

This configuration is between two AS5300s. The first configuration is a complete configuration of an AS5300. This is followed by a second configuration that shows just the necessary commands for only enabling Multichassis Multilink PPP (MMP) on the second AS5300.

Note: This router is also configured for Terminal Access Controller Access Control System (TACACS+), which is often used to authenticate a large number of users. You can also use Remote Authentication Dial-in User Service (RADIUS).

Note: Use the Command Lookup Tool (registered customers only) to find more information on the commands used in this document.

Network Diagram

This document uses this network setup:

multilink.gif

Configurations

This document uses these configurations:

  • AS5300-A

  • AS5300-B

AS5300-A

 
version 11.2
service timestamps debug datetime msec
service password-encryption
no service udp-small-servers
no service tcp-small-servers
!
hostname as5300-a
!
aaa new-model
aaa authentication login default tacacs+ line
aaa authentication login console none
aaa authentication ppp default tacacs+ none
aaa authorization network tacacs+
aaa accounting network start-stop tacacs+
enable secret letmedostuff
!
username syed password letmein
username stack password bar  

!--- Authenticates stack group (other 5300).

!
ip subnet-zero
multilink virtual-template 1
!
sgbp group stack	   		 

!--- Name of stack group (username above).

sgbp member as5300-b 192.168.38.19 	 

!--- Name of the other router in stack group.     
 
async-bootp dns-server 192.168.38.2
isdn switch-type primary-5ess
!
controller T1 0
 framing esf
 clock source line primary
 linecode b8zs
 pri-group timeslots 1-24
!
controller T1 1
 framing esf
 clock source line secondary
 linecode b8zs
 pri-group timeslots 1-24
!
controller T1 2
 framing esf
 clock source internal
 linecode b8zs
 pri-group timeslots 1-24
!
controller T1 3
 framing esf
 clock source internal
 linecode b8zs
 pri-group timeslots 1-24
!
interface Loopback0
 ip address 192.168.34.1 255.255.255.128
!
interface Ethernet0
 ip address 192.168.38.15 255.255.255.0
!
interface Virtual-Template1
 ip unnumbered Ethernet0
 no ip mroute-cache
 ppp authentication chap
 ppp multilink
!
interface Serial0:23
 no ip address
 encapsulation ppp
 no ip mroute-cache
 isdn incoming-voice modem
 no peer default ip address
 dialer rotary-group 1
 dialer-group 1
 no fair-queue
!
interface Serial1:23
 no ip address
 encapsulation ppp
 no ip mroute-cache
 isdn incoming-voice modem
 no peer default ip address
 dialer rotary-group 1
 dialer-group 1
 no fair-queue
!
interface Serial2:23
 no ip address
 encapsulation ppp
 no ip mroute-cache
 isdn incoming-voice modem
 no peer default ip address
 dialer rotary-group 1
 dialer-group 1
 no fair-queue
!
interface Serial3:23
 no ip address
 encapsulation ppp
 no ip mroute-cache
 isdn incoming-voice modem
 no peer default ip address
 dialer rotary-group 1
 dialer-group 1
 no fair-queue
!
interface FastEthernet0
 no ip address
!
interface Group-Async1
 ip unnumbered Loopback0
 ip tcp header-compression passive
 encapsulation ppp
 async default routing
 async mode interactive
 peer default ip address pool dialup
 dialer in-band
 dialer idle-timeout 900
 dialer-group 1
 no cdp enable
 ppp authentication pap chap
 group-range 1 96
!
interface Dialer1
 ip unnumbered Loopback0
 encapsulation ppp
 peer default ip address pool dialup
 dialer in-band
 dialer idle-timeout 900
 dialer-group 1
 no fair-queue
 ppp authentication chap
 ppp multilink
!
ip local pool dialup 192.168.34.32 192.168.34.126
no ip classless
ip route 0.0.0.0 0.0.0.0 192.168.38.1
no logging buffered
access-list 101 permit ip any any
tacacs-server host 192.168.38.2
tacacs-server key bubba5300
snmp-server community bubba97 RW
dialer-list 1 protocol ip permit
!
line con 0
 login authentication console
line 1 96
 autoselect ppp
 autoselect during-login
 modem InOut
 transport input all
line aux 0
line vty 0 4
 exec-timeout 20 0
 password letmein
!         
end

Note: This configuration example contains only the necessary commands to enable MMP on the second AS5300.

AS5300-B

 
!
username stack password bar      

!--- Authenticates stack group on other AS5300.

!						
multilink virtual-template 1
!
sgbp group stack		  

!--- Name of stack group (same name used above).

sgbp member as5300-a 192.168.38.15 

!--- List as5300-a as another member of stack group.

!
interface Virtual-Template1
 ip unnumbered Ethernet0
 no ip mroute-cache
 ppp authentication chap
 ppp multilink

Verify

There is currently no verification procedure available for this configuration.

Troubleshoot

Use this section to troubleshoot your configuration.

Troubleshooting Procedure

Follow these instructions to troubleshoot your configuration.

  1. The first thing to try if you encounter problems is to go back to a single stack member, and disable all other stack members. Then test your PPP Multilink connections, and go through the usual Challenge Handshake Authentication Protocol (CHAP) authentication and interface configuration for errors in the configuration and so forth. If the configuration works, enable the other stack members, and then proceed as follows:

  2. Make sure the Stack Group Bidding Protocol (SGBP) is up and running.

    • debug sgbp hellos

    • debug sgbp error

  3. Debug PPP Multilink.

    • show ppp multilink

  4. Debug Virtual Private Dial-up Network (VPDN) and Layer 2 Forwarding Protocol (L2F).

    • debug vpdn event

    • debug vpdn error

    • debug vpdn l2x-error

Related Information

Updated: Dec 05, 2005 Document ID: 9578