300-410 Question 21
Single answerA network engineer has configured route redistribution between OSPF and BGP on a Cisco router. However, the OSPF-learned routes are not visible in the BGP table. Upon investigation, the engineer confirms that the redistribute ospf command has been configured under the BGP process. What could be the reason for this issue?
- A
The OSPF routes lack a matching route-map or prefix-list in the redistribution configuration.
- B
The
default-information originatecommand is missing in the OSPF configuration. - C
The OSPF routes are external Type 2 (E2), and BGP does not redistribute E2 routes by default.
- D
The OSPF routes do not have a valid next-hop IP address.
Show answer and explanation
Correct answer: A
Explanation
In this scenario, the most likely issue is the absence of a route-map, prefix-list, or filtering mechanism in the redistribution configuration. When redistributing OSPF routes into BGP, these mechanisms are commonly required to control which routes are redistributed. Without such a configuration, the OSPF routes may not appear in the BGP table.
- A. Correct.
When redistributing OSPF routes into BGP, a route-map, prefix-list, or filter may be required to specify which routes to allow. Without this, the redistribution command might not include the intended routes.
- B. Incorrect.
The
default-information originatecommand is used to advertise a default route in OSPF, but it is unrelated to redistributing OSPF routes into BGP. - C. Incorrect.
BGP is capable of redistributing OSPF external Type 2 (E2) routes; there is no default limitation preventing this.
- D. Incorrect.
The OSPF routes must have a valid next-hop address to be redistributed, but this issue is unrelated to the configuration described in the scenario.