Troubleshooting IPv6 FlexVPN Connectivity

A.

To troubleshoot an IPv6 Flex VPN spoke-to-hub connectivity failure, the recommended command to use is "show crypto ikev2 sa". This command displays the current Internet Key Exchange Version 2 (IKEv2) Security Associations (SA) established between the Flex VPN spoke and hub.

IKEv2 is used to establish and manage the secure tunnels between the spoke and hub devices in a Flex VPN topology. By using the "show crypto ikev2 sa" command, network administrators can verify if the IKEv2 SA has been established successfully between the spoke and hub devices. If the SA is not established, it indicates that there is an issue with the IKEv2 negotiation between the devices, which could be caused by a misconfiguration, connectivity issues, or incorrect authentication settings.

Additionally, this command displays the details about the IKEv2 SA, including the tunnel mode, encryption and authentication algorithms, and the lifetime of the SA. By examining the output of this command, network administrators can identify any configuration issues and troubleshoot the connectivity problem accordingly.

The other answer options are not relevant for troubleshooting an IPv6 Flex VPN spoke-to-hub connectivity failure. "show crypto isakmp sa" displays the current Internet Security Association and Key Management Protocol (ISAKMP) SA established between devices, which is not specific to IKEv2 or Flex VPN. "show crypto gkm" displays the Group Key Management (GKM) protocol details, which is used for multicast group encryption, not for Flex VPN. Finally, "show crypto identity" displays the identity information, which is not relevant for troubleshooting connectivity issues.