300-420 · Question #9
A company with multiple service providers wants to speed up BGP convergence time in the event a failure occurs with their primary link. Which approach achieves this goal and does not impact router…
The correct answer is D. Utilize BFD and keep the default BGP timers. BFD (Bidirectional Forwarding Detection) is a lightweight, hardware-assisted hello protocol that can detect link or path failures in milliseconds - far faster than BGP's default keepalive/hold timers (60/180 seconds). When BFD detects a failure, it immediately notifies BGP…
Question
A company with multiple service providers wants to speed up BGP convergence time in the event a failure occurs with their primary link. Which approach achieves this goal and does not impact router CPU utilization?
Options
- AUtilize BFD and tune the multiplier to 50
- BLower the BGP hello interval
- CDecrease the BGP keepalive timer
- DUtilize BFD and keep the default BGP timers
How the community answered
(56 responses)- A7% (4)
- B11% (6)
- C4% (2)
- D79% (44)
Explanation
BFD (Bidirectional Forwarding Detection) is a lightweight, hardware-assisted hello protocol that can detect link or path failures in milliseconds - far faster than BGP's default keepalive/hold timers (60/180 seconds). When BFD detects a failure, it immediately notifies BGP, triggering fast convergence without requiring BGP to poll more frequently. Keeping the default BGP timers means BGP itself does not increase its processing frequency, so CPU utilization is not impacted. Lowering the BGP hello interval (B) or decreasing the BGP keepalive timer (C) forces BGP to process more control-plane messages, increasing CPU load. Using BFD with a multiplier of 50 (A) dramatically increases the detection timeout (making BFD slow and defeating its purpose).
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