300-410 · Question #41
Refer to the exhibit. The exhibit shows Router R1 connected to the 192.168.130.0/24 network. R1 has interfaces Gi0/1 (IP 172.20.40.3/30) and Gi0/2 (IP 172.20.20.3/30). R2 has interface Gi0/1 (IP…
The correct answer is D. access-list 1 permit 192.168.130.0 0.0.0.255 ! interface Gi0/1 ip policy route-map test ! route-map test permit 10 match ip address 1 set ip next-hop 172.20.40.1. This configuration uses policy-based routing (PBR) to redirect traffic originating from the 192.168.130.0/24 network that enters R1 on interface Gi0/1, explicitly directing it to a next-hop IP address of 172.20.40.1 to achieve forwarding towards R2.
Question
Options
- Aaccess-list 1 permit 192.168.130.0 0.0.0.255 ! interface Gi0/2 ip policy route-map test ! route-map test permit 10 match ip address 1 set ip next-hop 172.20.20.2
- Baccess-list 1 permit 192.168.130.0 0.0.0.255 ! interface Gi0/1 ip policy route-map test ! route-map test permit 10 match ip address 1 set ip next-hop 172.20.40.2
- Caccess-list 1 permit 192.168.130.0 0.0.0.255 ! interface Gi0/2 ip policy route-map test ! route-map test permit 10 match ip address 1 set ip next-hop 172.20.20.1
- Daccess-list 1 permit 192.168.130.0 0.0.0.255 ! interface Gi0/1 ip policy route-map test ! route-map test permit 10 match ip address 1 set ip next-hop 172.20.40.1
How the community answered
(28 responses)- A14% (4)
- B4% (1)
- C7% (2)
- D75% (21)
Why each option
This configuration uses policy-based routing (PBR) to redirect traffic originating from the 192.168.130.0/24 network that enters R1 on interface Gi0/1, explicitly directing it to a next-hop IP address of 172.20.40.1 to achieve forwarding towards R2.
The `set ip next-hop 172.20.20.2` is not the correct next-hop for R2's directly connected interface (172.20.20.4) and applying the policy on Gi0/2 assumes traffic from 192.168.130.0/24 enters R1 on that interface, which is less commonly implied for a 'LAN' source.
While applying the policy on Gi0/1 might be correct if 192.168.130.0/24 traffic enters there, the `set ip next-hop 172.20.40.2` is an IP on the R1-R3 segment and not the stated R2 interface (172.20.20.4), thus it does not directly fulfill the requirement of forwarding to R2.
Applying the policy on Gi0/2 is likely incorrect for ingress traffic from the source network, and the `set ip next-hop 172.20.20.1` is not the correct next-hop for R2's directly connected interface (172.20.20.4).
This configuration correctly implements policy-based routing by first defining an access-list to match the source network 192.168.130.0/24. The `ip policy route-map test` command is then applied to R1's interface Gi0/1, which is presumed to be the ingress interface for traffic from the 192.168.130.0/24 network. Finally, the route-map's `set ip next-hop 172.20.40.1` command explicitly directs this matched traffic to the specified IP address, overriding the router's default forwarding decision based on the destination IP to ensure it's directed towards R2 via this specific next-hop, possibly through an intermediary router.
Concept tested: Policy-based routing configuration (PBR)
Source: https://www.cisco.com/c/en/us/td/docs/ios/12_2/qos/configuration/guide/fqos_c/qcfpolbr.html
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