Google Professional Cloud Network Engineer Question 679
Single answerGoogle Cloud PlatformYou are configuring a hybrid network between your on-premises data center and Google Cloud using Cloud VPN with a BGP session. Your on-premises router uses ASN 65001. You want to prioritize traffic over one specific VPN tunnel while ensuring the backup tunnel is used only when the primary fails. How should you configure the BGP attributes to achieve this?
- A
Use the same MED value on both tunnels and configure a higher local preference for the primary tunnel.
- B
Set a lower MED value for the primary tunnel and a higher MED value for the backup tunnel.
- C
Use different ASNs for the primary and backup tunnels to prioritize one over the other.
- D
Configure BGP authentication on the primary tunnel only.
Show answer and explanation
Correct answer: B
Explanation
To prioritize traffic over a specific VPN tunnel in a hybrid network, you should use the MED attribute. A lower MED value indicates higher preference, influencing how the on-premises router selects the preferred path for inbound traffic. In this scenario, setting a lower MED value for the primary tunnel ensures it is prioritized, while the higher MED value on the backup tunnel ensures it is used only when the primary tunnel fails.
- A. Incorrect.
Using the same MED value and modifying local preference is incorrect because local preference is not a BGP attribute used in hybrid networks involving different autonomous systems.
- B. Correct.
Setting a lower MED (Multi-Exit Discriminator) value for the primary tunnel ensures that traffic is prioritized over this tunnel. The MED attribute is used to influence inbound traffic when multiple exit points exist between two ASNs.
- C. Incorrect.
Using different ASNs for the primary and backup tunnels is incorrect because both tunnels are part of the same connection between the on-premises network and Google Cloud, and the same ASN should be used for your on-premises router in this scenario.
- D. Incorrect.
Configuring BGP authentication on the primary tunnel only is incorrect because authentication does not influence the prioritization of traffic; it is solely used for securing BGP sessions.