Refer to the exhibit. An engineer must ensure that all traffic entering AS 200 from AS 100 chooses Link 2 as an entry point. Assume that all BGP neighbor relationships have been formed and that the at

Question

Exhibits

Options

• AR3(config)#route-map PREPEND permit 10
• BR4(config)#route-map PREPEND permit 10
• CR4(config)#route-map PREPEND permit 10
• DR3(config)#route-map PREPEND permit 10

• A
  79% (30)
• B
  3% (1)
• C
  5% (2)
• D
  13% (5)

Explanation

BGP AS Path Prepending for Inbound Traffic Control

Option A is correct because to influence inbound traffic into AS 200, you must apply AS path prepending outbound on the AS 100 side - specifically on R3, which advertises routes out via Link 1. By prepending extra AS numbers to routes advertised from R3 (Link 1), AS 100's path appears longer and less preferred, forcing AS 200 to prefer Link 2 as the entry point.

Option B is incorrect because applying prepending on R4 (inside AS 200) affects outbound traffic leaving AS 200, not inbound traffic entering it. Options C and D likely contain incorrect route-map configurations (wrong AS numbers being prepended, or the route-map applied in the wrong direction), making them ineffective for the stated goal. Remember that the question specifies no attributes have been changed, so the solution must work from the advertising side (AS 100).

Memory Tip: Think "To control where traffic ENTERS, manipulate what you ADVERTISE OUT." Inbound traffic engineering = prepend on the sending side's outbound updates. The router doing the prepending should be in the source AS, advertising out the link you want to make less attractive.

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