Basic L2TP Virtual Private Dialup Network (VPDN) for Dialin and Dialout

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Updated:January 29, 2008

Document ID:9556

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Introduction

Prerequisites

Requirements

Components Used

Conventions

Configure

Network Diagram

Configurations

Verify

Verification

Troubleshoot

Troubleshooting Commands

Debug on the LNS

Related Information

Introduction

This document provides a sample configuration for Layer 2 Tunneling Protocol (L2TP) for dialin and dialout calls.

Note: This setup does not involve an authentication, authorization, and accounting (AAA) server.

Prerequisites

Requirements

There are no specific requirements for this document.

Components Used

The information in this document is based on Cisco IOS® Software Release 12.1.

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

For more information on document conventions, refer to the Cisco Technical Tips Conventions .

Configure

In this section, you are presented with the information to configure the features described in this document.

Note: To find additional information on the commands used in this document, use the Command Lookup Tool (registered customers only) .

Network Diagram

This document uses this network setup:

Configurations

This document uses these configurations:

Router remote1:

Loopback0: 17.17.17.1/32 Username: remote1@cisco.com ISDN number (BRI 0): 6122
Router remote2:

Loopback: 17.17.17.2/32 Username: remote2@cisco.com ISDN number (BRI 0): 6121
Router LAC:

Loopback: 18.18.18.1/32 ISDN number (E1 0): 8211 Serial interface (S0): 18.18.18.6/30
Router LNS:

Loopback: 18.18.18.2/32 Serial interface (S0): 18.18.18.5/30 Ethernet interface (E0): 10.200.20.24/24
Router local1:

Loopback: 17.17.17.3/32 Ethernet interface (E0): 10.200.20.32/24

Routers remote1@cisco.com and remote2@cisco.com use ISDN to access the L2TP Access Concentrator (LAC). A back-to-back serial link connects the LAC and the L2TP Network Server (LNS) in this setup. The local1 router and the LNS share the same Ethernet link

Here is the process:

L2TP Dialin: The remote1@cisco.com client wants to communicate with the local1 router. The client generates an ISDN call to the LAC, which brings up an L2TP tunnel to the LNS and then the L2TP session. The LAC uses the domain name to bring up the tunnel with the LNS. The LNS authenticates the remote users locally.
L2TP Dialout: The local1 router wants to communicate with the remote2@cisco.com remote client. The LNS uses the existing tunnel with the LAC and creates a new L2TP session.

Note: These configurations are truncated to display the relevant information.

LAC
hostname LAC ! ! ip subnet-zero no ip domain-lookup ! vpdn enable no vpdn logging vpdn search-order domain !--- VPDN tunnel authorization is based on the domain only. ! vpdn-group 1 request-dialin !--- Enables the LAC to make requests to the LNS for dialin. protocol l2tp domain cisco.com accept-dialout !--- Enables the LAC to accept requests from the LNS for dialout. protocol l2tp dialer 1 !--- Specifies the dialer used to dial out. terminate-from hostname LNS initiate-to ip 18.18.18.2 local name LAC l2tp tunnel password l2tptunnel source-ip 18.18.18.1 ! isdn switch-type primary-net5 ! ! controller E1 0 clock source line primary pri-group timeslots 1-31 ! interface Loopback0 ip address 18.18.18.1 255.255.255.255 ! interface Ethernet0 ip address 10.200.20.34 255.255.255.0 no ip route-cache no ip mroute-cache no cdp enable ! ! interface Serial0 description -- Connection to the LNS ip address 18.18.18.6 255.255.255.252 no fair-queue clockrate 64000 no cdp enable ! interface Serial0:15 no ip address encapsulation ppp dialer rotary-group 1 isdn switch-type primary-net5 no cdp enable ppp authentication chap ppp chap hostname LAC ! interface Dialer1 ip unnumbered Loopback0 encapsulation ppp dialer in-band dialer aaa !--- L2TP dialout functionality requires this command even if you do not use AAA. dialer-group 1 no cdp enable ppp authentication chap ppp chap hostname LAC ppp chap password 7 1511021F0725 ! no ip http server ip classless ip route 18.18.18.2 255.255.255.255 18.18.18.5 ! dialer-list 1 protocol ip permit no cdp run

LAC

hostname LAC 
! 
! 
ip subnet-zero 
no ip domain-lookup 
! 
vpdn enable 
no vpdn logging 
vpdn search-order domain 

!--- VPDN tunnel authorization is based on the domain only.

! 
vpdn-group 1 
request-dialin 

!--- Enables the LAC to make requests to the LNS for dialin.

protocol l2tp 
domain cisco.com 
accept-dialout 

!--- Enables the LAC to accept requests from the LNS for dialout.

protocol l2tp 
dialer 1 

!--- Specifies the dialer used to dial out.

terminate-from hostname LNS 
initiate-to ip 18.18.18.2 
local name LAC 
l2tp tunnel password l2tptunnel 
source-ip 18.18.18.1 
! 
isdn switch-type primary-net5 
! 
! 
controller E1 0 
clock source line primary 
pri-group timeslots 1-31 
! 
interface Loopback0 
ip address 18.18.18.1 255.255.255.255 
! 
interface Ethernet0 
ip address 10.200.20.34 255.255.255.0 
no ip route-cache 
no ip mroute-cache 
no cdp enable 
! 
! 
interface Serial0 
description -- Connection to the LNS 
ip address 18.18.18.6 255.255.255.252 
no fair-queue 
clockrate 64000 
no cdp enable 
! 
interface Serial0:15 
no ip address 
encapsulation ppp 
dialer rotary-group 1 
isdn switch-type primary-net5 
no cdp enable 
ppp authentication chap 
ppp chap hostname LAC 
! 
interface Dialer1 
ip unnumbered Loopback0 
encapsulation ppp 
dialer in-band 
dialer aaa 

!--- L2TP dialout functionality requires this command even if you do not use AAA.
  
dialer-group 1 
no cdp enable 
ppp authentication chap 
ppp chap hostname LAC 
ppp chap password 7 1511021F0725 
! 
no ip http server 
ip classless 
ip route 18.18.18.2 255.255.255.255 18.18.18.5 
! 
dialer-list 1 protocol ip permit 
no cdp run

LNS
hostname LNS ! vpdn enable vpdn-group 1 accept-dialin !--- Enables the LNS to accept request from the LAC for dialin. protocol l2tp virtual-template 1 !--- For each user, a virtual-access is cloned from this virtual-template. request-dialout !--- Enables the LNS to request the LAC for dialout. protocol l2tp pool-member 1 !--- Specifies the dialer profile to be used to dial out. terminate-from hostname LAC initiate-to ip 18.18.18.1 local name LNS l2tp tunnel password l2tptunnel source-ip 18.18.18.2 ! ! interface Loopback0 ip address 18.18.18.2 255.255.255.255 ! interface Ethernet0 ip address 10.200.20.24 255.255.255.0 no ip route-cache no ip mroute-cache ! interface Virtual-Template1 ip unnumbered Loopback0 no peer default ip address ppp chap hostname LNS ! interface Serial0 description -- Connection to the LAC ip address 18.18.18.5 255.255.255.252 no ip route-cache no ip mroute-cache ! interface Dialer1 !--- For each user, a dialer profile is configured. ip unnumbered Loopback0 encapsulation ppp dialer pool 1 !--- "dialer pool 1" must match "pool-member 1" in the VPDN-group. dialer remote-name remote1@cisco.com dialer string 6122 !--- ISDN number that the LAC uses to dialout the remote client remote1@cisco.com. dialer vpdn !--- Enables the dialer profile to use L2TP dialout, and so place a VPDN call. dialer-group 1 ppp authentication chap callin ppp chap hostname LNS ! interface Dialer2 ip unnumbered Loopback0 encapsulation ppp dialer pool 1 dialer remote-name remote2@cisco.com dialer string 6121 dialer vpdn dialer-group 1 no cdp enable ppp authentication chap callin ppp chap hostname LNS ! no ip http server ip classless ip route 10.200.16.26 255.255.255.255 10.200.20.1 ip route 17.17.17.1 255.255.255.255 Dialer1 ip route 17.17.17.2 255.255.255.255 Dialer2 ip route 17.17.17.3 255.255.255.255 10.200.20.32 ip route 18.18.18.1 255.255.255.255 18.18.18.6 ! dialer-list 1 protocol ip permit no cdp run

LNS

hostname LNS
!
vpdn enable
vpdn-group 1 
accept-dialin

!--- Enables the LNS to accept request from the LAC for dialin.
 
protocol l2tp 
virtual-template 1 

!--- For each user, a virtual-access is cloned from this virtual-template.
 
request-dialout 

!--- Enables the LNS to request the LAC for dialout.
 
protocol l2tp 
pool-member 1 

!--- Specifies the dialer profile to be used to dial out.
 
terminate-from hostname LAC 
initiate-to ip 18.18.18.1 
local name LNS 
l2tp tunnel password l2tptunnel 
source-ip 18.18.18.2 
! 
! 
interface Loopback0 
ip address 18.18.18.2 255.255.255.255 
! 
interface Ethernet0 
ip address 10.200.20.24 255.255.255.0 
no ip route-cache 
no ip mroute-cache 
! 
interface Virtual-Template1 
ip unnumbered Loopback0 
no peer default ip address 
ppp chap hostname LNS 
! 
interface Serial0 
description -- Connection to the LAC 
ip address 18.18.18.5 255.255.255.252 
no ip route-cache 
no ip mroute-cache 
! 
interface Dialer1 

!--- For each user, a dialer profile is configured.
 
ip unnumbered Loopback0 
encapsulation ppp 
dialer pool 1 

!--- "dialer pool 1" must match "pool-member 1" in the VPDN-group.
 
dialer remote-name remote1@cisco.com 
dialer string 6122 

!--- ISDN number that the LAC uses to dialout the remote client remote1@cisco.com.

dialer vpdn 

!--- Enables the dialer profile to use L2TP dialout, and so place a VPDN call.
 
dialer-group 1 
ppp authentication chap callin 
ppp chap hostname LNS 
! 
interface Dialer2 
ip unnumbered Loopback0 
encapsulation ppp 
dialer pool 1 
dialer remote-name remote2@cisco.com 
dialer string 6121 
dialer vpdn 
dialer-group 1 
no cdp enable 
ppp authentication chap callin 
ppp chap hostname LNS 
! 
no ip http server 
ip classless 
ip route 10.200.16.26 255.255.255.255 10.200.20.1 
ip route 17.17.17.1 255.255.255.255 Dialer1 
ip route 17.17.17.2 255.255.255.255 Dialer2 
ip route 17.17.17.3 255.255.255.255 10.200.20.32 
ip route 18.18.18.1 255.255.255.255 18.18.18.6 
! 
dialer-list 1 protocol ip permit 
no cdp run

Verify

This section provides information you can use to confirm your configuration is working properly.

Certain show commands are supported by the Output Interpreter Tool (registered customers only) , which allows you to view an analysis of show command output.

show vpdn—displays information about active Level 2 Forwarding (L2F) protocol tunnel and message identifiers in a Virtual Private Dialup Network (VPDN).

LAC#show debug 
Dial on demand:   
  Dial on demand events debugging is on 
VPN:   
  L2X protocol events debugging is on   
  VPDN events debugging is on 
PPP:   
  PPP authentication debugging is on   
  PPP protocol negotiation debugging is on 
ISDN:   
  ISDN events debugging is on 
  
  ISDN events debug DSLs. (On/Off/No DSL:1/0/-) 
   DSL 0 --> 1 
   1 - 

LNS#show debug 
Dial on demand:   
  Dial on demand events debugging is on 
VPN:   
  L2X protocol events debugging is on   
  VPDN events debugging is on 
PPP:   
  PPP authentication debugging is on   
  PPP protocol negotiation debugging is on 
VTEMPLATE:   
  Virtual Template debugging is on

Verification

Dial In

The remote1@cisco.com router initiates a call to the local1 router.

LAC#

An ISDN call comes into the LAC.

Sep 29 02:25:42.923: ISDN Se0:15: Incoming call id = 0x011B, dsl 0 
Sep 29 02:25:42.927: Negotiated CCB->int_id 0 B-chan 0, req->int_id 0, B-chan 18 
Sep 29 02:25:42.931: CCPRI_ReleaseChan CCB->B_Chan zero 
Sep 29 02:25:42.939: ISDN Se0:15: received CALL_INCOMING call_id 0x11B 
Sep 29 02:25:42.939: ISDN Se0:15: CALL_INCOMING: call type is DATA , bchan = 17 
Sep 29 02:25:42.943: ISDN Se0:15: Event: Received a DATA call from 6122 on B17
 at 64 Kb/s 
Sep 29 02:25:42.947: ISDN Se0:15: RM returned call_type 0 resource type 0      
Sep 29 02:25:42.959: ISDN Se0:15: isdn_send_connect(): msg 74, call id 0x11B,
 ces 1 bchan 17, call type DATA 
Sep 29 02:25:43.031: %LINK-3-UPDOWN: Interface Serial0:17, changed state to up 
Sep 29 02:25:43.059: Se0:17 PPP: Treating connection as a callin 
Sep 29 02:25:43.063: Se0:17 PPP: Phase is ESTABLISHING, Passive Open 
Sep 29 02:25:43.067: Se0:17 LCP: State is Listen 
Sep 29 02:25:43.127: ISDN Se0:15: received CALL_PROGRESSing call_id 0x11B      
Sep 29 02:25:43.199: Se0:17 LCP: I CONFREQ [Listen] id 125 len 10 
Sep 29 02:25:43.203: Se0:17 LCP: MagicNumber 0xEB818699 (0x0506EB818699) 
Sep 29 02:25:43.207: Se0:17 LCP: O CONFREQ [Listen] id 7 len 15 
Sep 29 02:25:43.211: Se0:17 LCP: AuthProto CHAP (0x0305C22305) 
Sep 29 02:25:43.215: Se0:17 LCP: MagicNumber 0x6BDE50CC (0x05066BDE50CC) 
Sep 29 02:25:43.219: Se0:17 LCP: O CONFACK [Listen] id 125 len 10 
Sep 29 02:25:43.223: Se0:17 LCP: MagicNumber 0xEB818699 (0x0506EB818699) 
Sep 29 02:25:43.247: Se0:17 LCP: I CONFACK [ACKsent] id 7 len 15 
Sep 29 02:25:43.251: Se0:17 LCP: AuthProto CHAP (0x0305C22305) 
Sep 29 02:25:43.255: Se0:17 LCP: MagicNumber 0x6BDE50CC (0x05066BDE50CC) 
Sep 29 02:25:43.259: Se0:17 LCP: State is Open 
Sep 29 02:25:43.259: Se0:17 PPP: Phase is AUTHENTICATING, by this end

The LAC sends a CHAP challenge to the client.

Sep 29 02:25:43.263: Se0:17 CHAP: Using alternate hostname LAC 
Sep 29 02:25:43.267: Se0:17 CHAP: O CHALLENGE id 7 len 24 from "LAC"

The LAC receives a CHAP response but does not authenticate the user. The LNS performs the authentication.

Sep 29 02:25:43.295: Se0:17 CHAP: I RESPONSE id 7 len 38 from "remote1@cisco.com"    
Sep 29 02:25:43.303: Se0:17 PPP: Phase is FORWARDING 
Sep 29 02:25:43.303: Se0:17 VPDN: Got DNIS string 211

The LAC checks whether the domain "cisco.com" exists, and then collects the information needed to bring up the tunnel with the LNS.

Sep 29 02:25:43.307: Se0:17 VPDN: Looking for tunnel -- cisco.com -- 
Sep 29 02:25:43.347: Se0:17 VPDN/LAC/1: Got tunnel info for cisco.com 
Sep 29 02:25:43.351: Se0:17 VPDN/LAC/1: LAC LAC 
Sep 29 02:25:43.351: Se0:17 VPDN/LAC/1: source-ip 18.18.18.1 
Sep 29 02:25:43.355: Se0:17 VPDN/LAC/1: l2tp-busy-disconnect yes 
Sep 29 02:25:43.359: Se0:17 VPDN/LAC/1: l2tp-tunnel-password xxxxxx 
Sep 29 02:25:43.359: Se0:17 VPDN/LAC/1: IP 18.18.18.2 
Sep 29 02:25:43.371: Se0:17 VPDN/1: curlvl 1 Address 0: 18.18.18.2, priority 1 
Sep 29 02:25:43.375: Se0:17 VPDN/1: Select non-active address 18.18.18.2, priority 1 
Sep 29 02:25:43.379: Tnl 45029 L2TP: SM State idle

The LAC brings up the tunnel with the LNS.

Sep 29 02:25:43.383: Tnl 45029 L2TP: O SCCRQ 
Sep 29 02:25:43.391: Tnl 45029 L2TP: Tunnel state change from idle to 
   wait-ctl-reply    
Sep 29 02:25:43.395: Tnl 45029 L2TP: SM State wait-ctl-reply 
Sep 29 02:25:43.399: Se0:17 VPDN: Find LNS process created 
Sep 29 02:25:43.403: Se0:17 VPDN: Forward to address 18.18.18.2 
Sep 29 02:25:43.403: Se0:17 VPDN: Pending 
Sep 29 02:25:43.411: Se0:17 VPDN: Process created 
Sep 29 02:25:43.463: Tnl 45029 L2TP: I SCCRP from LNS 
Sep 29 02:25:43.467: Tnl 45029 L2TP: Got a challenge from remote peer, LNS 
Sep 29 02:25:43.471: Tnl 45029 L2TP: Got a response from remote peer, LNS 
Sep 29 02:25:43.475: Tnl 45029 L2TP: Tunnel Authentication success 
Sep 29 02:25:43.479: Tnl 45029 L2TP: Tunnel state change from wait-ctl-reply 
   to established 
Sep 29 02:25:43.483: Tnl 45029 L2TP: O SCCCN to LNS tnlid 11407 
Sep 29 02:25:43.487: Tnl 45029 L2TP: SM State established 
Sep 29 02:25:43.495: Se0:17 VPDN: Forwarding... 
Sep 29 02:25:43.499: Se0:17 DDR: Authenticated host remote1@cisco.com with no 
   matching dialer map 
Sep 29 02:25:43.503: Se0:17 VPDN: Bind interface direction=1 
Sep 29 02:25:43.507: Tnl/Cl 45029/291 L2TP: Session FS enabled 
Sep 29 02:25:43.511: Tnl/Cl 45029/291 L2TP: Session state change from idle to 
   wait-for-tunnel 
Sep 29 02:25:43.515: Se0:17 Tnl/Cl 45029/291 L2TP: Create session 
Sep 29 02:25:43.519: Tnl 45029 L2TP: SM State established

The LAC brings up the session for the user remote1@cisco.com.

Sep 29 02:25:43.523: Se0:17 Tnl/Cl 45029/291 L2TP: O ICRQ to LNS 11407/0 
Sep 29 02:25:43.531: Se0:17 Tnl/Cl 45029/291 L2TP: Session state change from 
   wait-for-tunnel to wait-reply 
Sep 29 02:25:43.535: Se0:17 VPDN: remote1@cisco.com is forwarded 
Sep 29 02:25:43.635: Se0:17 Tnl/Cl 45029/291 L2TP: O ICCN to LNS 11407/303 
Sep 29 02:25:43.639: Se0:17 Tnl/Cl 45029/291 L2TP: Session state change from 
   wait-reply to established 
Sep 29 02:25:44.535: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0:17, 
   changed state to up 
Sep 29 02:25:49.055: %ISDN-6-CONNECT: Interface Serial0:17 is now connected to 
6122 remote1@cisco.com 
   
LAC#show vpdn 

L2TP Tunnel and Session Information Total tunnels 1 sessions 1 

LocID RemID Remote Name State Remote Address Port Sessions 
45029 11407 LNS est 18.18.18.2 1701 1 

LocID RemID TunID Intf Username State Last Chg Fastswitch 
291 303 45029 Se0:17 remote1@cisco.com est 00:00:14 enabled 

% No active L2F tunnels

Dial Out

The local1 router initiates a call to the remote2@cisco.com router.

LAC#

The LAC receives a request from the LNS to bring up a new session for dialout.

Sep 29 02:26:19.479: Tnl 45029 L2TP: I OCRQ from LNS tnl 11407 
Sep 29 02:26:19.483: Tnl/Cl 45029/292 L2TP: Session FS enabled 
Sep 29 02:26:19.487: Tnl/Cl 45029/292 L2TP: New session created 
Sep 29 02:26:19.491: 1D4C: Same state, 0 
Sep 29 02:26:19.495: DSES 1D4C: Session create 
Sep 29 02:26:19.499: L2TP: Send OCRP 
Sep 29 02:26:19.503: Tnl/Cl 45029/292 L2TP: Session state change from 
idle to wait-cs-answer

The LAC uses ISDN to call the number 6121.

Sep 29 02:26:19.511: DSES 0x1D4C: Building dialer map 
Sep 29 02:26:19.511: Dialout 0x1D4C: Next hop name is 6121 
Sep 29 02:26:19.515: Se0:15 DDR: rotor dialout [priority] 
Sep 29 02:26:19.519: Se0:15 DDR: Dialing cause dialer session 0x1D4C 
Sep 29 02:26:19.523: Se0:15 DDR: Attempting to dial 6121 
Sep 29 02:26:19.523: ISDN Se0:15: Outgoing call id = 0x8055, dsl 0 
Sep 29 02:26:19.527: ISDN Se0:15: Event: Call to 6121 at 64 Kb/s 
Sep 29 02:26:19.531: ISDN Se0:15: process_pri_call(): call id 0x8055, 
   number 6121, speed 64, call type DATA 
Sep 29 02:26:19.539: building outgoing channel id for call nfas_int is 0 len is 0 
Sep 29 02:26:19.623: ISDN Se0:15: received CALL_ACCEPT call_id 0x8055 
Sep 29 02:26:19.623: ISDN Se0:15: PRI Event: CALL_ACCEPT, bchan = 30, 
   call type = DATA 
Sep 29 02:26:20.043: ISDN Se0:15: received CALL_CONNECT call_id 0x8055 
Sep 29 02:26:20.115: %LINK-3-UPDOWN: Interface Serial0:30, changed state to up 
Sep 29 02:26:20.147: Di1: Session free, 1D4C 
Sep 29 02:26:20.151: : 0 packets unqueued and discarded 
Sep 29 02:26:20.155: Se0:30 VPDN: Bind interface direction=1 
Sep 29 02:26:20.159: Se0:30 Tnl/Cl 45029/292 L2TP: Session state change 
   from wait-cs-answer to established 
Sep 29 02:26:20.163: L2TP: Send OCCN

The LAC bounds the ISDN session se0:30 with the VPDN session.

Sep 29 02:26:20.167: Se0:30 VPDN: bound to vpdn session 
Sep 29 02:26:20.175: ISDN Se0:15: received CALL_PROGRESSing call_id 0x8055 
Sep 29 02:26:26.143: %ISDN-6-CONNECT: Interface Serial0:30 is now connected to 6121
LAC# 
LAC#show vpdn 

L2TP Tunnel and Session Information Total tunnels 1 sessions 2 

LocID RemID Remote Name State Remote Address Port Sessions 
45029 11407 LNS est 18.18.18.2 1701 2 

LocID RemID TunID Intf Username State Last Chg Fastswitch 
291 303 45029 Se0:17 remote1@cisco.com est 00:00:57 enabled 
292 304 45029 Se0:30 est 00:00:20 enabled 

% No active L2F tunnels 
LAC#

Troubleshoot

This section provides information you can use to troubleshoot your configuration.

Troubleshooting Commands

Certain show commands are supported by the Output Interpreter Tool (registered customers only) , which allows you to view an analysis of show command output.

Note: Before issuing debug commands, please see Important Information on Debug Commands.

debug dialer events—displays debugging information about the packets received on a dialer interface.
debug vpdn l2x-events—displays messages about events that are part of normal tunnel establishment or shutdown.
debug vpdn l2x-packets—displays each protocol packet exchanged. This command can result in a large number of debug messages. Use this command only on a debug chassis with a single active session.
debug vpdn l2x-errors—displays errors that prevent the establishment of a tunnel or errors that cause an established tunnel to be closed.
debug ppp negotiation—causes the debug ppp command to display PPP packets transmitted during PPP startup, where PPP options are negotiated.
debug ppp authentication—causes the debug ppp command to display authentication protocol messages. The messages include Challenge Handshake Authentication Protocol (CHAP) packet exchanges and Password Authentication Protocol (PAP) exchanges.
debug isdn events—displays Integrated Services Digital Network (ISDN) events that occur on the user side (on the router) of the ISDN interface.
debug isdn q931—displays information about call setup and teardown of ISDN network connections (layer 3) between the local router (user side) and the network.
debug vtemplate—displays cloning information for a virtual access interface from the time it is cloned from a virtual template to the time the virtual access interface comes down when the call ends.

Debug on the LNS

Dial In

The remote1@cisco.com router initiates a call to the local1 router.

The LNS receives a request from the LAC to bring up a tunnel.

Sep 29 02:25:44.531: L2TP: I SCCRQ from LAC tnl 45029 
Sep 29 02:25:44.539: Tnl 11407 L2TP: Got a challenge in SCCRQ, LAC 
Sep 29 02:25:44.543: Tnl 11407 L2TP: New tunnel created for remote LAC, 
   address 18.18.18.1 
Sep 29 02:25:44.547: Tnl 11407 L2TP: O SCCRP to LAC tnlid 45029 
Sep 29 02:25:44.555: Tnl 11407 L2TP: Tunnel state change from idle to 
   wait-ctl-reply    
Sep 29 02:25:44.623: Tnl 11407 L2TP: I SCCCN from LAC tnl 45029 
Sep 29 02:25:44.627: Tnl 11407 L2TP: Got a Challenge Response in SCCCN from LAC 
Sep 29 02:25:44.631: Tnl 11407 L2TP: Tunnel Authentication success 
Sep 29 02:25:44.635: Tnl 11407 L2TP: Tunnel state change from wait-ctl-reply 
   to established 
Sep 29 02:25:44.639: Tnl 11407 L2TP: SM State established

The LNS receives a request from the LAC to bring up a session.

Sep 29 02:25:44.667: Tnl 11407 L2TP: I ICRQ from LAC tnl 45029 
Sep 29 02:25:44.671: Tnl/Cl 11407/303 L2TP: Session FS enabled 
Sep 29 02:25:44.679: Tnl/Cl 11407/303 L2TP: Session state change from idle 
   to wait-connect 
Sep 29 02:25:44.679: Tnl/Cl 11407/303 L2TP: New session created 
Sep 29 02:25:44.683: Tnl/Cl 11407/303 L2TP: O ICRP to LAC 45029/291 
Sep 29 02:25:44.791: Tnl/Cl 11407/303 L2TP: I ICCN from LAC tnl 45029, cl 291    
Sep 29 02:25:44.799: Tnl/Cl 11407/303 L2TP: Session state change from wait-connect 
   to established

The LNS clones the virtual-access for the user remote1@cisco.com.

Sep 29 02:25:44.803: Vt1 VTEMPLATE: Unable to create and clone vaccess 
Sep 29 02:25:44.803: Vi2 VTEMPLATE: Reuse Vi2, recycle queue size 1 
Sep 29 02:25:44.807: Vi2 VTEMPLATE: Hardware address 0060.4780.ac23 
Sep 29 02:25:44.807: Vi2 VPDN: Virtual interface created for remote1@cisco.com    
Sep 29 02:25:44.811: Vi2 PPP: Phase is DOWN, Setup 
Sep 29 02:25:44.815: Vi2 VPDN: Clone from Vtemplate 1 filterPPP=0 blocking 
Sep 29 02:25:44.819: Vi2 VTEMPLATE: Has a new cloneblk vtemplate, 
   now it has vtemplate 
Sep 29 02:25:44.827: Vi2 VTEMPLATE: ********** CLONE VACCESS2 **************    
Sep 29 02:25:44.827: Vi2 VTEMPLATE: Clone from Virtual-Template1 interface 
Virtual-Access2    
encapsulation ppp 
ip unnumbered loopback 0 
ppp chap hostname LNS 
ppp authentication chap 
end 

Sep 29 02:25:46.975: %LINK-3-UPDOWN: Interface Virtual-Access2, 
   changed state to up
Sep 29 02:25:46.995: Vi2 PPP: Using set call direction 
Sep 29 02:25:46.999: Vi2 PPP: Treating connection as a callin 
Sep 29 02:25:46.999: Vi2 PPP: Phase is ESTABLISHING, Passive Open 
Sep 29 02:25:47.003: Vi2 LCP: State is Listen 
Sep 29 02:25:47.007: Vi2 VPDN: Bind interface direction=2 
Sep 29 02:25:47.007: Vi2 LCP: I FORCED CONFREQ len 11 
Sep 29 02:25:47.011: Vi2 LCP: AuthProto CHAP (0x0305C22305) 
Sep 29 02:25:47.015: Vi2 LCP: MagicNumber 0x6BDE50CC (0x05066BDE50CC)

The LNS receives the LCP layer that the LAC negotiated with the remote1@cisco.com client. Therefore, the LNS does not renegotiate LCP with the client.

Sep 29 02:25:47.019: Vi2 VPDN: PPP LCP accepted rcv CONFACK 
Sep 29 02:25:47.019: Vi2 VPDN: PPP LCP accepted sent CONFACK 
Sep 29 02:25:47.023: Vi2 PPP: Phase is AUTHENTICATING, by this end 
Sep 29 02:25:47.023: Vi2 CHAP: Using alternate hostname LNS 
Sep 29 02:25:47.027: Vi2 CHAP: O CHALLENGE id 8 len 24 from "LNS"    
Sep 29 02:25:47.039: Vi2 CHAP: I RESPONSE id 7 len 38 from "remote1@cisco.com"    
Sep 29 02:25:47.051: Vi2 CHAP: O SUCCESS id 7 len 4 
Sep 29 02:25:47.055: Vi2 PPP: Phase is UP 
Sep 29 02:25:47.059: Vi2 IPCP: O CONFREQ [Not negotiated] id 1 len 10 
Sep 29 02:25:47.063: Vi2 IPCP: Address 18.18.18.2 (0x030612121202) 
Sep 29 02:25:47.111: Vi2 IPCP: I CONFREQ [REQsent] id 110 len 10 
Sep 29 02:25:47.115: Vi2 IPCP: Address 17.17.17.1 (0x030611111101) 
Sep 29 02:25:47.119: Vi2 IPCP: O CONFACK [REQsent] id 110 len 10 
Sep 29 02:25:47.123: Vi2 IPCP: Address 17.17.17.1 (0x030611111101) 
Sep 29 02:25:47.127: Vi2 IPCP: I CONFACK [ACKsent] id 1 len 10 
Sep 29 02:25:47.131: Vi2 IPCP: Address 18.18.18.2 (0x030612121202) 
Sep 29 02:25:47.135: Vi2 IPCP: State is Open 
Sep 29 02:25:47.143: Vi2 IPCP: Install route to 17.17.17.1 
Sep 29 02:25:48.131: %LINEPROTO-5-UPDOWN: Line protocol on 
Interface Virtual-Access2, changed state to up 

LNS#show vpdn 

L2TP Tunnel and Session Information Total tunnels 1 sessions 1 

LocID RemID Remote Name State Remote Address Port Sessions 
11407 45029 LAC est 18.18.18.1 1701 1 

LocID RemID TunID Intf Username State Last Chg Fastswitch 
303 291 11407 Vi2 remote1@cisco.com est 00:00:22 enabled 

% No active L2F tunnels

Dial Out

The local1 router initiates a call to the remote2@cisco.com router.

LNS# 
Sep 29 02:26:20.531: Vi1 VTEMPLATE: Reuse Vi1, recycle queue size 0 
Sep 29 02:26:20.531: Vi1 VTEMPLATE: Hardware address 0060.4780.ac23 
Sep 29 02:26:20.535: Vi1 PPP: Phase is DOWN, Setup 
Sep 29 02:26:20.543: Vi1 VTEMPLATE: Has a new cloneblk dialer, now it has dialer    
Sep 29 02:26:20.547: Vi1 DDR: Dialing cause ip (s=10.200.20.32, d=17.17.17.2)    
Sep 29 02:26:20.551: Vi1 DDR: Attempting to dial 6121 
Sep 29 02:26:20.555: Tnl/Cl 11407/304 L2TP: Session FS enabled 
Sep 29 02:26:20.559: Tnl/Cl 11407/304 L2TP: Session state change from idle 
   to wait-for-tunnel 
Sep 29 02:26:20.563: Tnl/Cl 11407/304 L2TP: Create dialout session 
Sep 29 02:26:20.567: Tnl 11407 L2TP: SM State established

The LNS sends a request to the LAC for dialout.

Sep 29 02:26:20.571: L2TP: O OCRQ 
Sep 29 02:26:20.575: Vi1 Tnl/Cl 11407/304 L2TP: Session state change from 
   wait-for-tunnel to wait-reply 
Sep 29 02:26:20.579: Vi1 VPDN: Bind interface direction=2 
Sep 29 02:26:20.635: Vi1 Tnl/Cl 11407/304 L2TP: I OCRP from LAC tnl 45029, cl 0 
Sep 29 02:26:20.639: Vi1 Tnl/Cl 11407/304 L2TP: Session state change from 
   wait-reply to wait-connect 
Sep 29 02:26:21.299: Vi1 Tnl/Cl 11407/304 L2TP: I OCCN from LAC tnl 45029, cl 292 
Sep 29 02:26:21.303: Vi1 Tnl/Cl 11407/304 L2TP: Session state change from 
   wait-connect to established 
Sep 29 02:26:21.307: Vi1 VPDN: Connection is up, start LCP negotiation now 
Sep 29 02:26:21.315: %LINK-3-UPDOWN: Interface Virtual-Access1, changed state to up
Sep 29 02:26:21.335: Vi1 DDR: Dialer statechange to up

The virtual-access 1 is bound to profile dialer 2 where the configuration for remote2@cisco.com is located.

Sep 29 02:26:21.335: %DIALER-6-BIND: Interface Vi1 bound to profile Di2 
Sep 29 02:26:21.339: Vi1 DDR: Dialer call has been placed

The PPP phase starts between the LNS and the remote2@cisco.com client.

Sep 29 02:26:21.343: Vi1 PPP: Treating connection as a callout 
Sep 29 02:26:21.343: Vi1 PPP: Phase is ESTABLISHING, Active Open 
Sep 29 02:26:21.347: Vi1 PPP: No remote authentication for call-out 
Sep 29 02:26:21.351: Vi1 LCP: O CONFREQ [Closed] id 1 len 10 
Sep 29 02:26:21.355: Vi1 LCP: MagicNumber 0x6F87121F (0x05066F87121F) 
Sep 29 02:26:21.427: Vi1 LCP: I CONFREQ [REQsent] id 79 len 39 
Sep 29 02:26:21.431: Vi1 LCP: AuthProto CHAP (0x0305C22305) 
Sep 29 02:26:21.435: Vi1 LCP: MagicNumber 0x059935DB (0x0506059935DB) 
Sep 29 02:26:21.435: Vi1 LCP: MRRU 1524 (0x110405F4) 
Sep 29 02:26:21.439: Vi1 LCP: EndpointDisc 1 Local 
Sep 29 02:26:21.443: Vi1 LCP: (0x13140172656D6F74653240636973636F) 
Sep 29 02:26:21.447: Vi1 LCP: (0x2E636F6D) 
Sep 29 02:26:21.451: Vi1 LCP: O CONFREJ [REQsent] id 79 len 28 
Sep 29 02:26:21.455: Vi1 LCP: MRRU 1524 (0x110405F4) 
Sep 29 02:26:21.455: Vi1 LCP: EndpointDisc 1 Local 
Sep 29 02:26:21.459: Vi1 LCP: (0x13140172656D6F74653240636973636F) 
Sep 29 02:26:21.463: Vi1 LCP: (0x2E636F6D) 
Sep 29 02:26:21.467: Vi1 LCP: I CONFACK [REQsent] id 1 len 10 
Sep 29 02:26:21.471: Vi1 LCP: MagicNumber 0x6F87121F (0x05066F87121F) 
Sep 29 02:26:21.559: Vi1 LCP: I CONFREQ [ACKrcvd] id 80 len 15 
Sep 29 02:26:21.563: Vi1 LCP: AuthProto CHAP (0x0305C22305) 
Sep 29 02:26:21.567: Vi1 LCP: MagicNumber 0x059935DB (0x0506059935DB) 
Sep 29 02:26:21.571: Vi1 LCP: O CONFACK [ACKrcvd] id 80 len 15 
Sep 29 02:26:21.575: Vi1 LCP: AuthProto CHAP (0x0305C22305) 
Sep 29 02:26:21.579: Vi1 LCP: MagicNumber 0x059935DB (0x0506059935DB) 
Sep 29 02:26:21.583: Vi1 LCP: State is Open 
Sep 29 02:26:21.583: Vi1 PPP: Phase is AUTHENTICATING, by the peer 
Sep 29 02:26:21.647: Vi1 CHAP: I CHALLENGE id 8 len 38 from "remote2@cisco.com"    
Sep 29 02:26:21.651: Vi1 CHAP: Using alternate hostname LNS 
Sep 29 02:26:21.655: Vi1 CHAP: O RESPONSE id 8 len 24 from "LNS" 
Sep 29 02:26:21.699: Vi1 CHAP: I SUCCESS id 8 len 4 
Sep 29 02:26:21.703: Vi1 PPP: Phase is UP 
Sep 29 02:26:21.707: Vi1 IPCP: O CONFREQ [Closed] id 1 len 10 
Sep 29 02:26:21.711: Vi1 IPCP: Address 18.18.18.2 (0x030612121202) 
Sep 29 02:26:21.715: Vi1 IPCP: I CONFREQ [REQsent] id 40 len 10 
Sep 29 02:26:21.719: Vi1 IPCP: Address 17.17.17.2 (0x030611111102) 
Sep 29 02:26:21.723: Vi1 IPCP: O CONFACK [REQsent] id 40 len 10 
Sep 29 02:26:21.727: Vi1 IPCP: Address 17.17.17.2 (0x030611111102) 
Sep 29 02:26:21.775: Vi1 IPCP: I CONFACK [ACKsent] id 1 len 10 
Sep 29 02:26:21.779: Vi1 IPCP: Address 18.18.18.2 (0x030612121202) 
Sep 29 02:26:21.783: Vi1 IPCP: State is Open 

Sep 29 02:26:21.791: Vi1 DDR: dialer protocol up 
Sep 29 02:26:21.795: Di2 IPCP: Install route to 17.17.17.2 
Sep 29 02:26:22.703: %LINEPROTO-5-UPDOWN: Line protocol on 
Interface Virtual-Access1, changed state to up 

LNS#show vpdn 

L2TP Tunnel and Session Information Total tunnels 1 sessions 2 

LocID RemID Remote Name State Remote Address Port Sessions 
11407 45029 LAC est 18.18.18.1 1701 2 

LocID RemID TunID Intf Username State Last Chg Fastswitch 
304 292 11407 Vi1 est 00:00:16 enabled 
303 291 11407 Vi2 remote1@cisco.com est 00:00:52 enabled 

% No active L2F tunnels

Related Information

Revision History

Revision	Publish Date	Comments
1.0	27-Nov-2001	Initial Release

Basic L2TP Virtual Private Dialup Network (VPDN) for Dialin and Dialout

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