The correct answer is B because upgrading the EPLD (Erasable Programmable Logic Device) on a fabric switching module of a Cisco MDS 9700 requires the affected module to be restarted or power-cycled so the new programmable logic can take effect. Since the EPLD resides on hardware components that participate directly in switching operations, the module cannot continue forwarding traffic normally while that hardware is being reinitialized.
As a result, traffic handled by that fabric module is interrupted during the restart cycle. This is the operational impact administrators must plan for when scheduling EPLD upgrades in a SAN environment. The disruption is tied to the specific module being upgraded, not to a normal supervisory switchover process.
Option A is incorrect because the question is about a fabric switching module, not a supervisor switchover event. Option C is also incorrect because the impact is not limited to control plane reload behavior; the data path through the upgraded module is affected. Option D is unrelated because FAN module behavior does not describe the consequence of upgrading a fabric switching module EPLD.
Therefore, the main impact is temporary interruption of traffic flow through the module due to the restart
/power cycle.