Cisco ASA IKEv1 and IKEv2 Support for IPSEC

IETF proposed an updated Internet Key Exchange (IKE) protocol, called IKEv2, which is used to simplify and improve the legacy IKE protocol (IKEv1).

Cisco ASA introduced support for IPSEC IKEv2 in software version 8.4(1) and later. In this ASA version, IKEv2 was added to support IPsec IKEv2 connections for AnyConnect and LAN-to-LAN VPN implementations.

Of course, legacy IKEv1 is still supported and is widely used in almost all VPN configurations up to now.

In this article I will show the differences between the commands used in ASA versions prior to 8.4(1) with commands used in versions 8.4(1) and later.

ASA version prior to 8.4(1)

Let’s start with a basic IPSEC Lan-to-Lan VPN configuration for ASA versions prior to 8.4(1). Note that the following are just a part of the commands required for successful Lan-to-Lan VPN.

The following are the commands which have some differences with the commands used in version 8.4(1) and later.

crypto ipsec transform-set espSHA3DESproto esp-3des esp-sha-hmac

crypto map IPSEC 10 match address VPN-TO-REMOTE
crypto map IPSEC 10 set pfs
crypto map IPSEC 10 set peer 100.100.100.2
crypto map IPSEC 10 set transform-set espSHA3DESproto
crypto map IPSEC interface outside

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

tunnel-group 100.100.100.2 type ipsec-l2l
tunnel-group 100.100.100.2 ipsec-attributes
pre-shared-key *****

ASA version 8.4(1) and later

Now let’s see how the IPSEC Lan-to-Lan VPN commands are changed in ASA version 8.4(1) and later. In red color you see the commands which are changed:

crypto ipsec ikev1 transform-set espSHA3DESproto esp-3des esp-sha-hmac

crypto map IPSEC 10 match address VPN-TO-REMOTE
crypto map IPSEC 10 set pfs
crypto map IPSEC 10 set peer 100.100.100.2
crypto map IPSEC 10 set ikev1 transform-set espSHA3DESproto
crypto map IPSEC interface outside

crypto isakmp identity address
crypto ikev1 enable outside
crypto ikev1 policy 10
authentication pre-share
encryption 3des
hash sha
group 2
lifetime 86400

tunnel-group 100.100.100.2 type ipsec-l2l
tunnel-group 100.100.100.2 ipsec-attributes
ikev1 pre-shared-key *****

The Table below shows a site by site comparison of commands for even older ASA versions. The leftmost column shows commands for ASA versions lower than 7.2(1). The middle column shows the commands in versions higher than 7.2(1) and lower than 8.4(1). The right column shows the commands from 8.4(1) and higher.

Table with Cisco ASA versions and command differences regarding Site-to-Site IPSEC VPN commands: