A backup path with floating static routes
R1 and R3 are joined directly by Gi0/2 (10.0.13.0/30): that's the main path between their LANs, and R1 and R3 already route over it. They are also both joined to R2, and R2 has routes to both LANs. Make the path through R2 a backup:
- Add floating static routes with AD 5: on R1 to 192.168.3.0/24 via R2 (10.0.12.2), on R3 to 192.168.1.0/24 via R2 (10.0.23.1).
- While the direct link works, traffic must still use it.
- Then test the backup: shut down R1 Gi0/2 and check that PC1 still reaches PC3.
How it works: this is VulnTech NetLab, a network simulator running in your browser. Click a device in the diagram to open its console and type commands, just like on real equipment (? shows help, Tab finishes a word). Click a cable to inspect it. Tasks tick themselves off as you complete them; questions are answered in the box under each task. Your work is kept if you reload; Reset starts the network over.
Solution explanation
Each router has two routes to the same /24, so the AD decides: 1 beats 5, and the backup stays out of the table. Shutting R1 Gi0/2 takes the link down at both ends, so R1 and R3 each lose their main route and install the AD 5 route through R2. R2 already knew both LANs, so traffic flows both ways. The backup works here because both routers see the failure on their own interface.
Show solution
[R3]
enable
show ip route 192.168.1.10
configure terminal
ip route 192.168.1.0 255.255.255.0 10.0.23.1 5
end
show ip route static
[R1]
enable
configure terminal
ip route 192.168.3.0 255.255.255.0 10.0.12.2 5
end
show ip route static
configure terminal
interface g0/2
shutdown
end
show ip route static
[PC1]
ping 192.168.3.10
tracert 192.168.3.10