Refer to the exhibit. An administrator is configuring a VPN tunnel on a Cisco router. The information provided by the administrator of the remote end of the VPN tunnel was that IKEv1 is the tunnel…

While ensuring identical IKE version is crucial, the debug message specifically refers to the *lack of an IKE SA*, not a version mismatch itself.

The debug message explicitly states "There is no IKE SA (SA of phase 1)," which signifies that the initial IKEv1 Phase 1 negotiation failed to complete successfully. This most commonly occurs when the ISAKMP (Phase 1) policy parameters, such as encryption, hashing, authentication method, DH group, or lifetime, are not identical on both ends of the VPN tunnel.

An incorrect preshared key would prevent the IKEv1 Phase 1 SA from establishing, but the debug message points to a general failure in SA establishment, and the ISAKMP policy encompasses all parameters including the key.

ACLs defining interesting traffic are relevant for IKEv1 Phase 2 (IPsec SA establishment) and define which traffic goes over the tunnel, but they do not prevent IKEv1 Phase 1 SA establishment itself, which is what the error message indicates.