300-415 Question 154
Single answerYour organization has deployed a Cisco SD-WAN solution connecting multiple branches and a data center. BGP is being used as the routing protocol between the SD-WAN edge devices and the local branch routers. During a troubleshooting session, you notice that some prefixes from the branch are not being advertised to the data center. Which configuration or action is required to resolve this issue?
- A
Ensure that the BGP AS numbers are correctly configured on both the SD-WAN edge device and the branch router.
- B
Enable BGP route reflection on the SD-WAN edge device to advertise the missing prefixes.
- C
Verify that the 'advertise bgp' command is enabled under the SD-WAN service VPN configuration.
- D
Check if a BGP route policy is filtering the prefixes on the SD-WAN edge device.
Show answer and explanation
Correct answer: D
Explanation
In Cisco SD-WAN, BGP route policies are used to control the advertisement of prefixes. If some prefixes are not being advertised to the data center, it is important to verify whether a route policy is filtering those prefixes on the SD-WAN edge device. Misconfigured or overly restrictive route policies can prevent certain routes from being shared.
- A. Incorrect.
If the BGP AS numbers are misconfigured, the BGP session will not establish at all. However, this scenario specifies that some prefixes are being advertised, so this is not the root cause.
- B. Incorrect.
BGP route reflection is used in scenarios involving route reflectors in large-scale iBGP deployments, which is irrelevant in this case as the issue pertains to prefix advertisement.
- C. Incorrect.
The 'advertise bgp' command does not exist in the SD-WAN configuration. Prefix advertisement relies on route policies and proper redistribution, not a specific SD-WAN command.
- D. Correct.
BGP route policies are commonly used to filter or modify routes. If some prefixes are not being advertised, it is likely due to a filtering policy applied on the SD-WAN edge device.