Implementing IKEv2 Route-Based Site-to-Site VPN on Cisco Routers Using IPv6

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Updated:July 10, 2025

Document ID:223291

Bias-Free Language

The documentation set for this product strives to use bias-free language. For the purposes of this documentation set, bias-free is defined as language that does not imply discrimination based on age, disability, gender, racial identity, ethnic identity, sexual orientation, socioeconomic status, and intersectionality. Exceptions may be present in the documentation due to language that is hardcoded in the user interfaces of the product software, language used based on RFP documentation, or language that is used by a referenced third-party product. Learn more about how Cisco is using Inclusive Language.

Local Router Configurations

Local Router Final Configuration

ISP Configuration

Remote Router Final Configuration

Verification

Troubleshoot

Introduction

This document describes a configuration to set up an IPv6, route-based, site-to-site tunnel between two Cisco routers using the Internet Key Exchange version 2 (IKEv2) protocol.

Prerequisites

Requirements

Cisco recommends that you have knowledge of these topics:

Fundamental knowledge of Cisco IOS®/Cisco IOS® XE CLI configuration
Fundamental knowledge of Internet Security Association and Key Management Protocol (ISAKMP) and IPsec protocols
Understanding of IPv6 addressing and routing

Components Used

The information in this document is based on these software versions:

Cisco IOS XE running 17.03.04a as Local Router
Cisco IOS running 17.03.04a as Remote Router

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, ensure that you understand the potential impact of any command.

Configure

Network Diagram

Local Router Configurations

Step 1. Enable IPv6 Unicast Routing.

ipv6 unicast-routing

Step 2. Configure the router interfaces.

interface GigabitEthernet1
ipv6 address 2001:DB8:1::1/64
no shutdown

interface GigabitEthernet2
ipv6 address FC00::1/64
no shutdown

Step 3. Set IPv6 Default Route.

ipv6 route ::/0 GigabitEthernet1

Step 4. Configure Ikev2 Proposal.

crypto ikev2 proposal IKEv2-PROP
encryption aes-cbc-128
integrity sha1
group 14

Step 5. Configure Ikev2 Policy.

crypto ikev2 policy IKEv2-POLI
proposal IKEv2-PROP

Step 6. Configure keyring with a pre-shared key.

crypto ikev2 keyring IPV6_KEY 
peer Remote_IPV6
 address 2001:DB8:2::2/64
 pre-shared-key cisco123

Step 7. Configure the Ikev2 profile.

crypto ikev2 profile IKEV2-PROF
 match identity remote address 2001:DB8:2::2/64
 authentication remote pre-share
 authentication local pre-share
 keyring local IPV6_KEY

Step 8. Configure the Phase 2 policy.

crypto ipsec transform-set ESP-AES-SHA esp-aes esp-sha-hmac 
mode tunnel

Step 9. Configure the IPsec profile.

crypto ipsec profile IPSEC-PROF
 set transform-set ESP-AES-SHA
 set ikev2-profile IKEV2-PROF

Step 10. Configure the tunnel interface.

interface Tunnel1
 ipv6 address 2001:DB8:3::1/64
 tunnel source GigabitEthernet1
 tunnel mode ipsec ipv6
 tunnel destination 2001:DB8:2::2
 tunnel protection ipsec profile IPSEC-PROF
end

Step 11. Configure the routes for the interesting traffic.

ipv6 route FC00::/64 2012::1

Local Router Final Configuration

ipv6 unicast-routing
!
interface GigabitEthernet1
ipv6 address 2001:DB8:1::1/64
no shutdown

!

interface GigabitEthernet2
ipv6 address FC00::1/64
no shutdown

!

ipv6 route ::/0 GigabitEthernet1

!

crypto ikev2 proposal IKEv2-PROP
encryption aes-cbc-128
integrity sha1
group 14

!

crypto ikev2 policy IKEv2-POLI
proposal IKEv2-PROP

!

crypto ikev2 keyring IPV6_KEY 
peer Remote_IPV6
 address 2001:DB8:2::2/64
 pre-shared-key cisco123

!

crypto ikev2 profile IKEV2-PROF
 match identity remote address 2001:DB8:2::2/64
 authentication remote pre-share
 authentication local pre-share
 keyring local IPV6_KEY

!

crypto ipsec transform-set ESP-AES-SHA esp-aes esp-sha-hmac 
mode tunnel

!

crypto ipsec profile Prof1
 set transform-set ESP-AES-SHA
 
 !
 
 crypto ipsec profile IPSEC-PROF
 set transform-set ESP-AES-SHA
 set ikev2-profile IKEV2-PROF

!

interface Tunnel1
 ipv6 address 2001:DB8:3::1/64
 tunnel source GigabitEthernet1
 tunnel mode ipsec ipv6
 tunnel destination 2001:DB8:2::2
 tunnel protection ipsec profile IPSEC-PROF
end

!

ipv6 route FC00::/64 2012::1

ISP Configuration

ipv6 unicast-routing
!
!
interface GigabitEthernet1
 description Link to R1
 ipv6 address 2001:DB8:1::2/64
!
interface GigabitEthernet2
 description Link to R3
 ipv6 address 2001:DB8:2::1/64
!
!
!
ipv6 route 2001:DB8:1::/64 GigabitEthernet1
ipv6 route 2001:DB8:2::/64 GigabitEthernet2
!

Remote Router Final Configuration

ipv6 unicast-routing
!
interface GigabitEthernet1
ipv6 address 2001:DB8:2::2/64
no shutdown

!

interface GigabitEthernet2
ipv6 address FC00::2/64
no shutdown

!

ipv6 route ::/0 GigabitEthernet1

!

crypto ikev2 proposal IKEv2-PROP
encryption aes-cbc-128
integrity sha1
group 14

!

crypto ikev2 policy IKEv2-POLI
proposal IKEv2-PROP

!

crypto ikev2 keyring IPV6_KEY 
peer Remote_IPV6
 address 2001:DB8:1::1/64
 pre-shared-key cisco123

!

crypto ikev2 profile IKEV2-PROF
 match identity remote address 2001:DB8:1::1/64
 authentication remote pre-share
 authentication local pre-share
 keyring local IPV6_KEY

!

crypto ipsec transform-set ESP-AES-SHA esp-aes esp-sha-hmac 
mode tunnel

!

crypto ipsec profile Prof1
 set transform-set ESP-AES-SHA
 
 !
 
 crypto ipsec profile IPSEC-PROF
 set transform-set ESP-AES-SHA
 set ikev2-profile IKEV2-PROF

!

interface Tunnel1
 ipv6 address 2001:DB8:3::2/64
 tunnel source GigabitEthernet1
 tunnel mode ipsec ipv6
 tunnel destination 2001:DB8:1::1
 tunnel protection ipsec profile IPSEC-PROF
end

!

ipv6 route FC00::/64 2012::1

Verification

On Router 1

R1#show crypto ikev2 sa
 IPv4 Crypto IKEv2  SA 

 IPv6 Crypto IKEv2  SA 

Tunnel-id    fvrf/ivrf              Status 
2          none/none             READY  
Local  2001:DB8:1::1/500                                 
Remote  2001:DB8:2::2/500                                 
      Encr: AES-CBC, keysize: 256, PRF: SHA256, Hash: SHA256, DH Grp:14, Auth sign: PSK, Auth verify: PSK
      Life/Active Time: 86400/75989 sec

R1#show crypto ipsec sa

interface: Tunnel1
    Crypto map tag: Tunnel1-head-0, local addr 2001:DB8:1::1

   protected vrf: (none)
   local  ident (addr/mask/prot/port): (::/0/0/0)
   remote ident (addr/mask/prot/port): (::/0/0/0)
   current_peer 2001:DB8:2::2 port 500
     PERMIT, flags={origin_is_acl,}
    #pkts encaps: 14, #pkts encrypt: 14, #pkts digest: 14
    #pkts decaps: 14, #pkts decrypt: 14, #pkts verify: 14
    #pkts compressed: 0, #pkts decompressed: 0
    #pkts not compressed: 0, #pkts compr. failed: 0
    #pkts not decompressed: 0, #pkts decompress failed: 0
    #send errors 0, #recv errors 0

     local crypto endpt.: 2001:DB8:1::1,
     remote crypto endpt.: 2001:DB8:2::2
     plaintext mtu 1422, path mtu 1500, ipv6 mtu 1500, ipv6 mtu idb GigabitEthernet1
     current outbound spi: 0x9DC2A6F6(2646779638)
     PFS (Y/N): N, DH group: none

     inbound esp sas:
      spi: 0x18569EF7(408329975)
        transform: esp-aes esp-sha-hmac ,
        in use settings ={Tunnel, }
        conn id: 2104, flow_id: CSR:104, sibling_flags FFFFFFFF80000049, crypto map: Tunnel1-head-0
         sa timing: remaining key lifetime (k/sec): (4608000/1193)
        IV size: 16 bytes
        replay detection support: Y
        Status: ACTIVE(ACTIVE)

     inbound ah sas:

     inbound pcp sas:

     outbound esp sas:
      spi: 0x9DC2A6F6(2646779638)
        transform: esp-aes esp-sha-hmac ,
        in use settings ={Tunnel, }
        conn id: 2103, flow_id: CSR:103, sibling_flags FFFFFFFF80000049, crypto map: Tunnel1-head-0
         sa timing: remaining key lifetime (k/sec): (4608000/1193)
        IV size: 16 bytes
        replay detection support: Y
        Status: ACTIVE(ACTIVE)

     outbound ah sas:

     outbound pcp sas:


On Router 2

R2#show crypto ikev2 sa
 IPv4 Crypto IKEv2  SA 

 IPv6 Crypto IKEv2  SA 

Tunnel-id    fvrf/ivrf              Status 
1          none/none             READY  
Local  2001:DB8:2::2/500                                 
Remote  2001:DB8:1::1/500                                 
      Encr: AES-CBC, keysize: 256, PRF: SHA256, Hash: SHA256, DH Grp:14, Auth sign: PSK, Auth verify: PSK
      Life/Active Time: 86400/19 sec

R2#show cryto ipsec sa

interface: Tunnel1
    Crypto map tag: Tunnel1-head-0, local addr 2001:DB8:2::2

   protected vrf: (none)
   local  ident (addr/mask/prot/port): (::/0/0/0)
   remote ident (addr/mask/prot/port): (::/0/0/0)
   current_peer 2001:DB8:1::1 port 500
     PERMIT, flags={origin_is_acl,}
    #pkts encaps: 14, #pkts encrypt: 14, #pkts digest: 14
    #pkts decaps: 14, #pkts decrypt: 14, #pkts verify: 14
    #pkts compressed: 0, #pkts decompressed: 0
    #pkts not compressed: 0, #pkts compr. failed: 0
    #pkts not decompressed: 0, #pkts decompress failed: 0
    #send errors 0, #recv errors 0

     local crypto endpt.: 2001:DB8:2::2,
     remote crypto endpt.: 2001:DB8:1::1
     plaintext mtu 1422, path mtu 1500, ipv6 mtu 1500, ipv6 mtu idb GigabitEthernet1
     current outbound spi: 0xEF1D3BA2(4011670434)
     PFS (Y/N): N, DH group: none

     inbound esp sas:
      spi: 0x9829B86D(2552871021)
        transform: esp-aes esp-sha-hmac ,
        in use settings ={Tunnel, }
        conn id: 2006, flow_id: CSR:6, sibling_flags FFFFFFFF80000049, crypto map: Tunnel1-head-0
         sa timing: remaining key lifetime (k/sec): (4608000/3556)
        IV size: 16 bytes
        replay detection support: Y
        Status: ACTIVE(ACTIVE)

     inbound ah sas:

     inbound pcp sas:

     outbound esp sas:
      spi: 0xEF1D3BA2(4011670434)
        transform: esp-aes esp-sha-hmac ,
        in use settings ={Tunnel, }
        conn id: 2005, flow_id: CSR:5, sibling_flags FFFFFFFF80000049, crypto map: Tunnel1-head-0
         sa timing: remaining key lifetime (k/sec): (4607998/3556)
        IV size: 16 bytes
        replay detection support: Y
        Status: ACTIVE(ACTIVE)

     outbound ah sas:

     outbound pcp sas:

Troubleshoot

In order to troubleshoot the tunnel, use these debug commands:

debug crypto ikev2
debug crypto ikev2 error
debug crypto ipsec
debug crypto ipsec error

Revision History

Revision	Publish Date	Comments
1.0	25-Jul-2025	Initial Release

Contributed by Cisco Engineers

Ekant Rai
Cisco TAC Engineer
Vamshi Sai Mahajan
Cisco TAC Engineer

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Implementing IKEv2 Route-Based Site-to-Site VPN on Cisco Routers Using IPv6

Available Languages

Download Options

Bias-Free Language

Contents

Introduction

Prerequisites

Requirements

Components Used

Configure

Network Diagram

Local Router Configurations

Local Router Final Configuration

ISP Configuration

Remote Router Final Configuration

Verification

Troubleshoot

Revision History

Contributed by Cisco Engineers

Was this Document Helpful?

Contact Cisco