A network engineer is designing a dual router, dual ISP solution and must prefer one ISP for inbound traffic over the other. Which two BGP attributes can be manipulated to accomplish this goal?…

Question

Options

• AAS path
• BMED
• Clocal preference
• Dweight
• Eorigin code

• A
  74% (29)
• C
  5% (2)
• D
  5% (2)
• E
  15% (6)

Explanation

Inbound traffic engineering means influencing how external ASes send traffic to you - you must manipulate attributes that are visible and meaningful to your upstream peers. A (AS path prepending) is correct: By artificially lengthening your AS path on announcements sent through the less-preferred ISP, you make that path look longer to the rest of the internet, causing remote ASes to prefer the other ISP's path to reach you. B (MED) is correct: MED (Multi-Exit Discriminator) is advertised to a directly connected neighboring AS to signal which of your entry points you prefer. It influences inbound traffic from that specific neighbor. C (Local preference) is incorrect - it is used internally within your own AS to influence outbound path selection and is not sent to external peers. D (Weight) is incorrect - it is Cisco-proprietary, locally significant to a single router only, and controls outbound path selection. E (Origin code) is incorrect - it is not used for traffic engineering purposes.

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