Google Professional Cloud Network Engineer Question 747
Select 2Google Cloud PlatformYou are troubleshooting a BGP peering issue between a Cloud Router in Google Cloud and your on-premises router. BGP sessions are not being established, and you suspect the configuration might be incorrect. Which of the following steps should you perform to identify and resolve the issue?
- A
Verify that the BGP ASN configured on the Cloud Router matches the ASN configured on the on-premises router.
- B
Check whether the IP addresses used for the BGP sessions are correctly configured and reachable between the Cloud Router and the on-premises router.
- C
Ensure that the Cloud Router has the appropriate IAM permissions to advertise routes.
- D
Verify that the firewall rules allow TCP traffic on port 179 (BGP) between the on-premises router and the Cloud Router.
- E
Check if the Cloud Router has enabled route advertisements for the correct subnets.
Show answer and explanation
Correct answers: B, D
Explanation
To resolve BGP peering issues, you need to ensure that the IP addresses used for the session are correctly configured and reachable, and that TCP port 179 is allowed through the firewall. These are the most common causes of BGP session failures. Other options, such as ASN mismatches or route advertisements, are unrelated to the immediate establishment of the BGP session.
- A. Incorrect.
The BGP ASN does not need to match between the Cloud Router and the on-premises router. They can have different ASNs as long as they are correctly configured for peering.
- B. Correct.
The IP addresses used for the BGP session must be correctly configured and reachable. If the IPs are incorrect or routes to the endpoints are missing, the BGP session will not establish.
- C. Incorrect.
IAM permissions are not relevant for BGP peering configuration. IAM permissions control access to Cloud Router configuration but do not impact BGP session establishment.
- D. Correct.
BGP uses TCP port 179 for its communication. If firewall rules block this port, the BGP session cannot be established.
- E. Incorrect.
Route advertisements affect the propagation of routes but do not impact the establishment of the BGP session itself.