Solution: How to Make Dynamic L2L Tunnels Fall into Different Tunnel Groups

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Updated:June 28, 2012

Document ID:113573

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Introduction

Prerequisites

Requirements

Components Used

Conventions

Symptom

Cause / Problem Description

Conditions / Environment

Resolution

Related Information

Introduction

This document provides information on how to make dynamic L2L tunnels fall into different tunnel groups.

Prerequisites

Requirements

There are no specific requirements for this document.

Components Used

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

Conventions

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

Symptom

In this document's example, the network administrator needs to create VPN policies where different remote VPN spokes connecting to a hub should connect to separate Tunnel-Groups so that different VPN policies can be applied to each remote connection.

Cause / Problem Description

In dynamic L2L tunnels, one side of the tunnel (the initiator) has a dynamic IP address. Because the receive does not know which IP addresses they are coming from, unlike static L2L tunnels, different peers automatically fall into the Default L2L Group. However, in some situations this is not acceptable and the user might need to assign a different group-policy or pre-shared key to each peer.

Conditions / Environment

Resolution

This can be accomplished in these two ways:

Certificates

The tunnel-group lookup process on the ASA will land the connections based on a certificate field presented by the spokes.

no tunnel-group-map enable rules
tunnel-group-map enable ou
tunnel-group-map enable ike-id
tunnel-group-map enable peer-ip
tunnel-group-map default-group DefaultRAGroup

PSKs and Aggressive Mode

Not all users will have a PKI infrastructure. However, the same can still be accomplished using an aggressive mode parameter as described here:

HUB

crypto ipsec transform-set myset esp-3des esp-sha-hmac
crypto ipsec security-association lifetime seconds 28800
crypto ipsec security-association lifetime kilobytes 4608000
crypto dynamic-map mydyn 10 set transform-set myset
crypto map mymap 65535 ipsec-isakmp dynamic mydyn
crypto map mymap interface outside

crypto isakmp enable outside
crypto isakmp policy 10
 authentication pre-share
 encryption 3des
 hash sha
 group 2
 lifetime 86400

tunnel-group SPOKE1 type ipsec-l2l
tunnel-group SPOKE1 ipsec-attributes
 pre-shared-key cisco123
tunnel-group SPOKE2 type ipsec-l2l
tunnel-group SPOKE2 ipsec-attributes
 pre-shared-key cisco456

SPOKE1

access-list interesting extended permit ip 
192.168.15.0 255.255.255.0 192.168.1.0 255.255.255.0

crypto ipsec transform-set myset esp-3des esp-sha-hmac
crypto ipsec security-association lifetime seconds 28800
crypto ipsec security-association lifetime kilobytes 4608000
crypto map mymap 10 match address interesting
crypto map mymap 10 set peer 10.198.16.141
crypto map mymap 10 set transform-set myset
crypto map mymap 10 set phase1-mode aggressive
crypto map mymap interface outside
crypto isakmp identity key-id SPOKE1
crypto isakmp enable outside
crypto isakmp policy 10
 authentication pre-share
 encryption 3des
 hash sha
 group 2
 lifetime 86400

tunnel-group 10.198.16.141 type ipsec-l2l
tunnel-group 10.198.16.141 ipsec-attributes
 pre-shared-key cisco123

SPOKE2

ip access-list extended interesting
 permit ip 192.168.16.0 0.0.0.255 192.168.1.0 0.0.0.255

crypto isakmp policy 10
 encr 3des
 authentication pre-share
 group 2

crypto isakmp peer address 10.198.16.141
 set aggressive-mode password cisco456
 set aggressive-mode client-endpoint fqdn SPOKE2

crypto ipsec transform-set myset esp-3des esp-sha-hmac

crypto map mymap 10 ipsec-isakmp
 set peer 10.198.16.141
 set transform-set myset
 match address interesting

interface FastEthernet0/0
 crypto map mymap

HUB VERIFICATION

Session Type: LAN-to-LAN Detailed

Connection   : SPOKE2
Index        : 59                     IP Addr      : 10.198.16.132
Protocol     : IKE IPsec
Encryption   : 3DES                   Hashing      : SHA1
Bytes Tx     : 400                    Bytes Rx     : 400
Login Time   : 23:45:00 UTC Thu Oct 27 2011
Duration     : 0h:00m:18s
IKE Tunnels: 1
IPsec Tunnels: 1

IKE:
  Tunnel ID    : 59.1
  UDP Src Port : 500                    UDP Dst Port : 500
  IKE Neg Mode : Aggressive             Auth Mode    : preSharedKeys
  Encryption   : 3DES                   Hashing      : SHA1
  Rekey Int (T): 86400 Seconds          Rekey Left(T): 86381 Seconds
  D/H Group    : 2
  Filter Name  :

IPsec:
  Tunnel ID    : 59.2
  Local Addr   : 192.168.1.0/255.255.255.0/0/0
  Remote Addr  : 192.168.16.0/255.255.255.0/0/0
  Encryption   : 3DES                   Hashing      : SHA1
  Encapsulation: Tunnel
  Rekey Int (T): 3600 Seconds           Rekey Left(T): 3581 Seconds
  Rekey Int (D): 4608000 K-Bytes        Rekey Left(D): 4608000 K-Bytes
  Idle Time Out: 30 Minutes             Idle TO Left : 29 Minutes
  Bytes Tx     : 400                    Bytes Rx     : 400
  Pkts Tx      : 4                      Pkts Rx      : 4

NAC:
  Reval Int (T): 0 Seconds              Reval Left(T): 0 Seconds
  SQ Int (T)   : 0 Seconds              EoU Age(T)   : 21 Seconds
  Hold Left (T): 0 Seconds              Posture Token:
  Redirect URL :

Connection   : SPOKE1
Index        : 60                     IP Addr      : 10.198.16.142
Protocol     : IKE IPsec
Encryption   : 3DES                   Hashing      : SHA1
Bytes Tx     : 400                    Bytes Rx     : 400
Login Time   : 23:45:12 UTC Thu Oct 27 2011
Duration     : 0h:00m:08s
IKE Tunnels: 1
IPsec Tunnels: 1

IKE:
  Tunnel ID    : 60.1
  UDP Src Port : 500                    UDP Dst Port : 500
  IKE Neg Mode : Aggressive             Auth Mode    : preSharedKeys
  Encryption   : 3DES                   Hashing      : SHA1
  Rekey Int (T): 86400 Seconds          Rekey Left(T): 86391 Seconds
  D/H Group    : 2
  Filter Name  :

IPsec:
  Tunnel ID    : 60.2
  Local Addr   : 192.168.1.0/255.255.255.0/0/0
  Remote Addr  : 192.168.15.0/255.255.255.0/0/0
  Encryption   : 3DES                   Hashing      : SHA1
  Encapsulation: Tunnel
  Rekey Int (T): 28800 Seconds          Rekey Left(T): 28791 Seconds
  Rekey Int (D): 4608000 K-Bytes        Rekey Left(D): 4608000 K-Bytes
  Idle Time Out: 30 Minutes             Idle TO Left : 29 Minutes
  Bytes Tx     : 400                    Bytes Rx     : 400
  Pkts Tx      : 4                      Pkts Rx      : 4

NAC:
  Reval Int (T): 0 Seconds              Reval Left(T): 0 Seconds
  SQ Int (T)   : 0 Seconds              EoU Age(T)   : 9 Seconds
  Hold Left (T): 0 Seconds              Posture Token:
  Redirect URL :