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11/06/2022 12:09 pm
An engineer configured Reverse Path Forwarding on an interface and noticed that the routes are dropped when a route lookup fails on that interface for a prefix that is available in the routing table.
Which interface configuration resolves the issue?
- A . ip verify unicast source reachable-via rx
- B . ip verify unicast source reachable-via any
- C . ip verify unicast source reachable-via allow-default
- D . ip verify unicast source reachable-via 12-src
Suggested Answer: B
Explanation:
According to this question, uRPF is running in strict mode because packets are dropped even
when that route exists in the routing table. Maybe packets are dropped because the receiving interface is different from the interface the local router uses to send packets to that destination. The ip verify unicast source reachable-via rx command enables Unicast RPF in strict mode. To enable loose mode, administrators can use the any option (ip verify unicast source reachable-via any). In loose mode, it doesn’t matter if we use this interface to reach the source or not.
Explanation:
According to this question, uRPF is running in strict mode because packets are dropped even
when that route exists in the routing table. Maybe packets are dropped because the receiving interface is different from the interface the local router uses to send packets to that destination. The ip verify unicast source reachable-via rx command enables Unicast RPF in strict mode. To enable loose mode, administrators can use the any option (ip verify unicast source reachable-via any). In loose mode, it doesn’t matter if we use this interface to reach the source or not.
The allow-default option allows the use of the default route in the source verification process.