PPTP, L2TP, L2TP over IPSEC important Debugs


Feb 1, 2012 10:12 PM
Jun 28th, 2011

Introduction: This document describes the useful commands for troubleshooting PPTP, L2TP and L2TP over ipsec related issues.

Q1.  PPTP Useful debugs Commands---


  • debug ppp io
  • debug ppp error
  • debug vpdn error
  • debug vpdn packet
  • debug vpdn event
  • debug ppp uauth



  • debug ppp authen
  • debug ppp nego
  • debug aaa auten
  • debug mppe event
  • debug mppe packet
  • debug vpdn event
  • debug vpdn error
  • debug vpdn packet

Show Commands----

  • show run – Display the running configuration
  • show vpdn - Display the active PPTP clients

VPN 3000 Concentrator

  • Config->events->classes; Add auth (severity to log: 13)
  • authdbg (severity to log: 13)
  • ppp (severity to log: 13)
  • pppdbg (severity to log: 13)
  • pptp (severity to log: 13)
  • pptpdbg (severity to log: 13

Q2.  L2TP useful debugs---


  • debug vpdn error
  • debug vpdn l2x-errors
  • debug vpdn l2x-events
  • debug vpdn l2x-packets

For AAA issues: (Along with above debugs)

  • debug radius
  • debug aaa authentication/authorization/accounting.

Show Commands----

  • show vpdn – Display the active L2TP clients
  • show ppp mppe virtual-Access 1 - Displays MPPE information for virtual-access interface 1

Q3.  L2TP over IPsec

  • debug crypto isakmp 7—Displays the ISAKMP negotiations of Phase 1
  • debug crypto ipsec 7—Displays the IPsec negotiations of Phase 2.
  • show crypto isakmp sa- Show all current IKE sessions
  • show crypto ipsec sa—Shows all current ISPEC security associations (SAs) at a peer.

Show Commands----

  • show crypto ipsec sa—Shows all current IKE security associations (SAs) at a peer.
  • show crypto isakmp sa—Shows all current IKE SAs at a peer
  • show vpn-sessiondb - Display information about VPN sessions
  • show vpn-sessiondb summary – Display Summary of VPN sessions





Overall Rating: 0 (0 ratings)


Login or Register to take actions

This Document

Posted June 28, 2011 at 10:05 PM
Updated February 1, 2012 at 10:12 PM
Comments:0 Overall Rating:0
Views:2682 Contributors:0

Related Content