A. Replace the failed unit, connect the correct cables, boot up the new node in recovery mode, upgrade firmware and restore, and save config Then, reboot and wait for VSX to synchronize.

B. Replace the failed unit, connect the correct cables, boot up the new node and wait for VSX to synchronize configuration and firmware.

C. Replace the failed unit, boot up the new node without connecting cables, upgrade firmware and configure as secondary vsx node connect iSl and wart for VSX to synchronize After successful recovery, reconnect the remaining cables.

D. Replace the failed unit, boot up the new node without connecting cables, upgrade firmware, and restore and save config Shutdown all ports, reconnect the correct cables, and enable all ports