Implementing Cisco Enterprise Advanced Routing and Services (ENARSI) — Question 444

How does BFD protocol work?

Answer options

• A. When BFD declares a failure on the primary IGP path, the router on the peer router chooses to use the secondary path.
• B. BFD operates on the route processor module and impacts the route processor CPU utilization.
• C. BFD control packets are sent via UDP port 3784 to the destination router.
• D. BFD echo packets are sent to the same source IP and different destination IP with TCP port of 3786.

Correct answer: C

Explanation

The correct answer is C because BFD control packets indeed use UDP port 3784 for communication between routers. Option A is incorrect as it refers to IGP path failure handling, which is not the primary function of BFD. Option B is misleading since BFD operates independently of the CPU utilization of the route processor, and option D incorrectly states that BFD echo packets use TCP port 3786, while they actually do not.