Task 1: Configure a host route on R1 for R6.

Host routes are specific routes that direct traffic to a single destination IP address and are configured with a subnet mask of 255.255.255.255 (/32), meaning a single address or a specific node.

On R1:

R1# configure terminal
R1(config)# ip route 172.16.6.2 255.255.255.255 172.16.1.2
R1# exit

This command configures a static host route to the IP address of G0/1 interface of R6 (172.16.6.2) via R2's G0/0 interface (172.16.1.2) as the next-hop.

Task 2: Configure a static default route on R2 through R3 towards R6.

A default route is a route used when no specific match exists in the routing table. It is denoted as 0.0.0.0/0. A default route is used to forward unknown traffic.

On R2:

R2# configure terminal
R2(config)# ip route 0.0.0.0 0.0.0.0 172.16.2.2

This command sets R3 as the primary next-hop for all unknown traffic passing through R2. Since R3 is already configured, it should have a route in place to reach R6.

Task 3: From R1, use traceroute and ping to verify the path to R6.

Ping is used to check reachability to a destination while traceroute shows the path taken to reach the destination.

On R1:

R1# ping 172.16.6.2

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.16.6.2, timeout is 2 seconds:
..!!!
Success rate is 60 percent (3/5), round-trip min/avg/max = 0/0/0 ms


R1# traceroute 172.16.6.2
Type escape sequence to abort.
Tracing the route to 172.16.6.2

1 172.16.1.2 0 msec 0 msec 0 msec =>R2
2 172.16.2.2 0 msec 0 msec 0 msec =>R3
3 172.16.4.2 0 msec 0 msec 0 msec =>R5
4 172.16.6.2 0 msec 0 msec 0 msec =>R6

The ping verifies basic reachability to R6 while traceroute shows the path taken to reach R6, confirming traffic passes through R2 and R3.

Task 4: Configure a floating static default route on R2 with AD of 10, which prefers the path through R4 towards R6 if the link to R3 fails.

A floating static route is a backup route with a higher Administrative Distance (AD) than the primary route. It is only used if the primary route fails. A floating static default route ensures that traffic can still reach R6 through R4 if primary path through R3 fails.

On R2:

R2(config)# ip route 0.0.0.0 0.0.0.0 172.16.3.2 10

This command configures a floating static default route with AD of 10 with R4's G0/0 interface as the next-hop. This ensures traffic is forwarded via R4 only if the link to R3 (primary path) is unavailable.

Task 5: Configure a host static route on R4 to forward the return traffic towards R1.

To ensure traffic coming from R6 can reach back to R1 if the primary path is unavailable, we need to configure a host static route on R4.

On R4:

R4# configure terminal
R4(config)# ip route 172.16.1.1 255.255.255.255 172.16.3.1

This command configures a static host route to the IP address of G0/0 interface of R1 (172.16.1.1) via R2's G0/1 interface (172.16.3.1) as the next-hop.

Task 6: After shutting the interface G0/2 on R2, use traceroute and ping from R1 to verify the path to R6.

Simulate the failure of the primary link by shutting down G0/2 on R2.

On R2:

R2(config)# interface g0/2
R2(config-if)# shutdown

Verify that traffic now takes the backup route via R4 using traceroute and ping.

On R1:

R1# ping 172.16.6.2

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.16.6.2, timeout is 2 seconds:
..!!!
Success rate is 60 percent (3/5), round-trip min/avg/max = 0/0/0 ms


R1# traceroute 172.16.6.2
Type escape sequence to abort.
Tracing the route to 172.16.6.2

1 172.16.1.2 0 msec 0 msec 0 msec =>R2
2 172.16.3.2 0 msec 0 msec 0 msec =>R4
3 172.16.4.2 0 msec 0 msec 0 msec =>R5
4 172.16.6.2 0 msec 0 msec 0 msec =>R6

The traceroute shows that the path taken to reach R6 is now from R2 to R4.

Now exit the configuration mode and save the configuration.

R1# write memory

R2(config-if)# end
R2# write memory

R4(config)# end
R4# write memory