Refer to the exhibit. Users connected to an application on 1.1.1.1 via routers CE1 and CE2 are complaining of frequent disconnections. While troubleshooting the issue, a network engineer with an…

Question

Exhibit

Options

• AEnable passive interface on the router R3 Loopback1 interface.
• BDisable split horizon on router R2.
• CEnable route dampening on routers R1 and R2.
• DRedistribute CE1 routes on router R2.

• A
  3% (1)
• B
  8% (3)
• C
  73% (27)
• D
  16% (6)

Explanation

The root cause is a flapping physical link to the 1.1.1.1 application server. Every time the link flaps, the route to 1.1.1.1 is withdrawn and re-advertised via BGP, causing active TCP sessions from CE1 and CE2 users to be torn down and re-established - resulting in the experienced disconnections. BGP route dampening addresses this by assigning a penalty each time a route flaps; when the accumulated penalty exceeds a suppress threshold, the route is suppressed (withheld from advertisement) until it stabilizes and the penalty decays below a reuse threshold. Enabling dampening on R1 and R2 prevents the unstable route from being repeatedly advertised and withdrawn, stabilizing connectivity for users. Option A (passive interface on loopback) does not address link flapping. Option B (disabling split horizon on R2) is unrelated to this scenario. Option D (redistributing CE1 routes on R2) does not solve the flapping issue. Route dampening on R1 and R2 is the correct mechanism to mitigate the impact of the flapping link.

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