Previous Post(Static Route Config)

https://velog.io/@serendipity/Cisco-Academy-Static-Router-Config

Topology

Each terminal can communicate with the others.
However, if the link between R0 and R1 is disconnected, then R0 can't forward packets whose destination is 203.230.11.0/24
This problem is called single-point failure.

To solve this kind of problem, we should draw floating routes.

Config for Redundant Routes

Redundant path has same destination, the other route, and lower prioity than primary route

R0

# R0
ip route 203.230.11.0 255.255.255.0 203.230.14.2 5
ip route 203.230.12.0 255.255.255.0 203.230.13.2 5

Link1 diconnected

Assumed that tracert from PC1 to the other terminals will success merely by configuring R0's detour.
However, R1 currently doesn't have any route to reply back to 203.230.10.0/24.
Accordingly, decided to intert detours into R1 and R2.

R1 and R2

# R1
ip route 203.230.10.0 255.255.255.0 203.230.15.1 5
ip route 203.230.12.0 255.255.255.0 203.230.13.1 5

# R2
ip route 203.230.10.0 255.255.255.0 203.230.15.2 5
ip route 203.230.11.0 255.255.255.0 203.230.14.1 5

tracert

Link1 disconnected

Expected Routes

PC0 -> PC1

PC1 -> PC0

Link2 disconnected

Expected Routes

PC0 -> PC2

PC2 -> PC0

Link3 disconnected

Expected Routes

PC1 -> PC2

PC2 -> PC1