Configure Prefix Delegation in VPDN Scenario

Introduction

This document describes Prefix Delegation configuration example in scenarios where Layer 2 Tunnelling Protocol Network Server (LNS)  delegates an IPv6 prefix to the Client router over Virtual Private Dialup Network (VPDN) Tunnel built between the Layer 2 Tunnelling Protocol Access Concentrator (LAC) and LNS.

Requirements

Cisco recommends that you have knowledge of End-to-End Layer 1 connectivity that is UP

Components Used

This document is not restricted to specific software and hardware versions.

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.

Network Diagram

This document uses this network setup:

Configurations

Client Configuration:

An example of the configuration on the Client router is shown here:

ipv6 unicast-routing
!
interface Ethernet0/0
 no ip address
 pppoe enable group global
 pppoe-client dial-pool-number 1
end
 

interface Dialer1
 ip address negotiated
 encapsulation ppp
 dialer pool 1
 ipv6 address FE80::1234 link-local
 ipv6 address autoconfig
 ipv6 enable
 no ipv6 nd ra suppress
 ipv6 dhcp client pd my-prefix1
 no keepalive
 ppp chap hostname test@cisco.com
 ppp chap password 0 cisco
 no cdp enable
end
!
interface FastEthernet0/2
 description -  This interface is connected to the LAN segment
 no ip address
 ipv6 address my-prefix1 ::1/64
 ipv6 enable

LAC Configuration:

An example of the configuration on the LAC  is shown here:

hostname LAC
!
vpdn enable
!
vpdn-group 1
 request-dialin
  protocol l2tp
  domain cisco.com
 initiate-to ip 192.168.1.2
 source-ip 192.168.1.1
 no l2tp tunnel authentication

!
bba-group pppoe global
virtual-template 1
!
interface Ethernet0/0
 no ip address
 pppoe enable group global
!
interface Ethernet1/0
  ip address 192.168.1.1 255.255.255.0
!
interface Virtual-Template1
 no ip address
 ppp authentication chap
!

LNS Configuration:

An example of the configuration on the LNS  is shown here:

ipv6 unicast-routing

!
vpdn enable
!
vpdn-group 1
accept-dialin
protocol l2tp
virtual-template 1
terminate-from hostname LAC
vpn vrf test
lcp renegotiation on-mismatch
no l2tp tunnel authentication
!
username test@cisco.com password cisco
interface Ethernet1/0
 ip vrf forwarding test
 ip address 192.168.1.2 255.255.255.0
 negotiation auto
 cdp enable
end
 
interface Virtual-Template1
 ip address 10.1.1.1 255.255.255.0
 ipv6 enable
 ipv6 dhcp server AAA
 peer default ip address pool local
 peer default ipv6 pool PPPOE_POOL6
 no keepalive
 ppp authentication chap
!
ipv6 dhcp pool AAA
 prefix-delegation pool DHCPv6Pool
!
ipv6 local pool PPPOE_POOL6 2001:DB8:5AB:10::/60 64
!
ip local pool local 10.1.1.2 10.1.1.100
!
ipv6 local pool DHCPv6Pool 2A02:838F:F880::/42 56
!

Verify

Client#show ipv6 interface brief FastEthernet0/2
FastEthernet0/2              [up/up]
    FE80::205:FF:FE77:2C1B
    2A02:838F:F880::1
 
Client#show ipv6 interface brief dialer1
Dialer1                [up/up]
    FE80::1234
    2001:DB8:5AB:10::1234

Troubleshoot on Client

These debugs assist in debugging the issue:

debug ppp negotiation
debug ipv6 dhcp detail

Client#show debug          
PPP:
  PPP protocol negotiation debugging is on
IPv6 DHCP:
   IPv6 DHCP debugging is on (detailed)

This a snippet of debug ipv6 dhcp detail on the Client router after PPP Negotiation has been completed and respective Virtual-Access is UP.
*Jun 27 15:08:53.019: %LINEPROTO-5-UPDOWN: Line protocol on Interface Virtual-Access2, changed state to up
*Jun 27 15:09:03.711: IPv6 DHCP: detailed packet contents
*Jun 27 15:09:03.711:   src FE80::1234
*Jun 27 15:09:03.711:   dst FF02::1:2 (Dialer1)
*Jun 27 15:09:03.711:   type REQUEST(3), xid 1849347
*Jun 27 15:09:03.711:   option ELAPSED-TIME(8), len 2
*Jun 27 15:09:03.711:     elapsed-time 3202
*Jun 27 15:09:03.711:   option CLIENTID(1), len 10
*Jun 27 15:09:03.711:     00030001000500772C1B
*Jun 27 15:09:03.711:   option ORO(6), len 6
*Jun 27 15:09:03.711:     IA-PD,DNS-SERVERS,DOMAIN-LIST
*Jun 27 15:09:03.711:   option SERVERID(2), len 10
*Jun 27 15:09:03.711:     000300017CAD74F9EB00
*Jun 27 15:09:03.711:   option IA-PD(25), len 41
*Jun 27 15:09:03.711:     IAID 0x000B0001, T1 0, T2 0
*Jun 27 15:09:03.711:     option IAPREFIX(26), len 25
*Jun 27 15:09:03.711:       preferred 0, valid 0, prefix 2A02:838F:F880::/56
*Jun 27 15:09:03.711: IPv6 DHCP: Sending REQUEST to FF02::1:2 on Dialer1
*Jun 27 15:09:03.711: IPv6 DHCP: Received REPLY from FE80::7EAD:74FF:FEF9:EB00 on Dialer1
*Jun 27 15:09:03.711: IPv6 DHCP: detailed packet contents
*Jun 27 15:09:03.711:   src FE80::7EAD:74FF:FEF9:EB00 (Dialer1)
*Jun 27 15:09:03.711:   dst FE80::1234 (Dialer1)
*Jun 27 15:09:03.711:   type REPLY(7), xid 1849347
*Jun 27 15:09:03.711:   option SERVERID(2), len 10
*Jun 27 15:09:03.711:     000300017CAD74F9EB00
*Jun 27 15:09:03.711:   option CLIENTID(1), len 10
*Jun 27 15:09:03.711:     00030001000500772C1B
*Jun 27 15:09:03.711:   option IA-PD(25), len 41
*Jun 27 15:09:03.711:     IAID 0x000B0001, T1 302400, T2 483840
*Jun 27 15:09:03.711:     option IAPREFIX(26), len 25
*Jun 27 15:09:03.711:       preferred 604800, valid 2592000, prefix 2A02:838F:F880::/56
*Jun 27 15:09:03.711: IPv6 DHCP: Processing options
*Jun 27 15:09:03.711: IPv6 DHCP: Adding prefix 2A02:838F:F880::/56 to my-prefix1
*Jun 27 15:09:03.711: IPv6 DHCP: T1 set to expire in 302400 seconds
*Jun 27 15:09:03.711: IPv6 DHCP: T2 set to expire in 483840 seconds
*Jun 27 15:09:03.711: IPv6 DHCP: DHCPv6 changes state from REQUEST to OPEN (REPLY_RECEIVED) on Dialer1