Introduction: This document describes the useful commands for troubleshooting PPTP, L2TP and L2TP over ipsec related issues.
Q1. PPTP Useful debugs Commands---
PIX:
- debug ppp io
- debug ppp error
- debug vpdn error
- debug vpdn packet
- debug vpdn event
- debug ppp uauth
Router:
- 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---
Router:
- 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
References-------
http://www.cisco.com/en/US/tech/tk827/tk369/technologies_configuration_example09186a0080094501.shtml
http://www.cisco.com/en/US/products/ps6120/products_configuration_example09186a00807213a7.shtml
http://www.cisco.com/en/US/products/hw/vpndevc/ps2030/products_configuration_example09186a0080093f89.shtml
