Required Configuration Tasks for VPN Clustering of AnyConnect Clients on Cisco ASA

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VPN clustering of AnyConnect clients on a Cisco ASA allows for the distribution of VPN connections across multiple ASA devices. This provides redundancy and load-balancing capabilities to the VPN service. When using Fully Qualified Domain Name (FQDN) for VPN clustering, there are three specific configuration tasks that are required:

A. The "redirect-fqdn" command must be entered under the "vpn load-balancing" sub-configuration: This command allows for the redirecting of AnyConnect VPN clients to the appropriate ASA device in the cluster. When a client attempts to connect to the VPN using the FQDN, the ASA will use the "redirect-fqdn" command to redirect the client to the appropriate ASA device. This command must be configured on all VPN cluster-member devices.

B. Each ASA in the VPN cluster must be able to resolve the IP of all DNS hostnames that are used in the cluster: This ensures that each ASA device in the VPN cluster can resolve the IP addresses of all FQDN hostnames used in the cluster. This is necessary to enable the redirecting of AnyConnect clients to the appropriate ASA device. DNS resolution can be achieved by configuring either a local DNS server or by using an external DNS server.

C. The identification and CA certificates for the master FQDN hostname must be imported into each VPN cluster-member device: This ensures that each VPN cluster-member device has the necessary certificates to verify the identity of the master FQDN hostname. These certificates include the identity certificate of the FQDN hostname and the CA certificate that issued the identity certificate. This step is necessary to ensure the security and integrity of the VPN connections.

D. The remote-access IP pools must be configured the same on each VPN cluster-member interface: This ensures that each VPN cluster-member device is using the same IP pool for remote-access VPN clients. This step is necessary to ensure that VPN clients can move seamlessly between different ASA devices in the cluster without any interruption to their VPN connection.

In summary, when using FQDN for VPN clustering, the necessary configuration tasks include configuring the "redirect-fqdn" command, ensuring that each ASA can resolve the IP of all DNS hostnames, importing the necessary certificates for the master FQDN hostname, and configuring the remote-access IP pools the same on each VPN cluster-member interface.