300-440 Question 32
Single answerA network engineer is tasked with configuring policy-based routing (PBR) on a Cisco router. The goal is to ensure traffic sourced from the 192.168.10.0/24 subnet is forwarded through a secondary WAN link (GigabitEthernet0/1) instead of the default route. After configuring the following commands, the traffic is still not being redirected as expected:
ip access-list extended PBR_ACL
permit ip 192.168.10.0 0.0.0.255 any
!
ip route-map PBR_ROUTE permit 10
match ip address PBR_ACL
set interface GigabitEthernet0/1
!
interface GigabitEthernet0/0
ip policy route-map PBR_ROUTE
What could be the reason the policy-based routing is not working?
- A
The route-map is missing a 'deny' statement to allow non-matching traffic to use the default route.
- B
The 'set interface' command in the route-map should specify the next-hop IP address instead of the interface.
- C
The policy-based routing is applied to the wrong interface.
- D
The ACL is incorrectly matching traffic from an unintended source.
Show answer and explanation
Correct answer: B
Explanation
Policy-based routing (PBR) allows traffic to be forwarded based on policies defined by route-maps. In this scenario, while the PBR configuration appears correct at first glance, the issue lies with the use of the 'set interface' command. Some Cisco IOS versions do not support the 'set interface' command for policy-based routing. Instead, the 'set ip next-hop' command should be used to define the next-hop IP address for the traffic. Correcting this would resolve the issue and ensure traffic is forwarded as intended.
- A. Incorrect.
This is incorrect because a 'deny' statement is not required in this scenario. Traffic that does not match the route-map will automatically follow the default routing table.
- B. Correct.
This is correct because the 'set interface' command in a route-map is not supported for forwarding traffic in all Cisco IOS versions. Instead, the 'set ip next-hop' command should be used to specify the next-hop IP address.
- C. Incorrect.
This is incorrect because the policy-based routing (PBR) has been correctly applied to the ingress interface (GigabitEthernet0/0).
- D. Incorrect.
This is incorrect because the ACL is correctly matching traffic from the 192.168.10.0/24 subnet.