Understanding the Purpose of Routing
Stop broadcasts
Allow packets to move from one network to another
By default, routers only know what they are plugged into
How Static Routing Can Help
Manually tell routers what networks they can reach
r2(config)#ip route 192.168.33.0 255.255.255.0 192.168.22.2
192.168.33.0 = Destination Network
255.255.255.0 = Destination Subnet Mask
192.168.22.2 = Next Hop IP Address
In order to return the traffic, you must also let the connecting router know how to get back!
r3(config)#ip route 192.168.11.0 255.255.25.0 192.168.22.1
Configure a default route
Default routes are used for anything that is unknown to the router
r2(config)#ip route 0.0.0.0 0.0.0.0 192.168.11.1
0.0.0.0 = Any unknown IP address
0.0.0.0 = Any subnet mask
192.168.11.1 = IP Address of next hop for router to access.
Configure DNS Name Servers
r1(config)#ip name-server IP.ADD.RE.SS
Putting it all together
Router #3
Starting Specs
Lab3 Ping r3 192.168.22.2: Yes
Lab3 Ping r2 192.168.22.1: No route to hose
Lab3 Ping r2 192.168.11.2: No route to host
Lab3 Ping r1 192.168.11.1: No route to host
Lab3 Ping Lab2 192.168.11.101: No route to host
r3 ping r2 192.168.22.1: Yes
r3 ping r2 192.168.11.2: No route to host
Option 1: Internal Only
r3(config)#ip route 192.168.11.0 255.255.255.0 192.168.22.1
Better: Routes anything unknown through Router 2
r3(config)#ip route 0.0.0.0 0.0.0.0 192.168.22.1
Results
Lab3 Ping r3 192.168.22.2: Yes
Lab3 Ping r2 192.168.22.1: No return route
Lab3 Ping r2 192.168.11.2: No return route
Lab3 Ping r1 192.168.11.1: No return route
Lab3 Ping Lab2 192.168.11.101: No return route
r3 ping r2 192.168.22.1: Yes
r3 ping r2 192.168.11.2: No return route
Router #2
Starting Specs
Lab3 Ping r3 192.168.22.2: Yes
Lab3 Ping r2 192.168.22.1: No return route
Lab3 Ping r2 192.168.11.2: No return route
Lab3 Ping r1 192.168.11.1: No return route
Lab3 Ping Lab2 192.168.11.101: No return route
r3 ping r2 192.168.22.1: Yes
r3 ping r2 192.168.11.2: No return route
r2 Ping r3 192.168.22.2: Yes
r2 Ping r3 192.168.33.1: No route to host
r2 Ping Lab3 192.168.33.20: No route to host
r2 Ping r1 192.168.11.1: Yes
r2 Ping Lab1 192.168.1.200: No route to host
Lab2 ping Lab3 192.168.33.20: No route to host
Route .33.0 Network
r2(config)#ip route 192.168.33.0 255.255.255.0 192.168.22.2
Lab3 Ping r3 192.168.22.2: Yes
Lab3 Ping r2 192.168.22.1: Yes
Lab3 Ping r2 192.168.11.2: Yes
Lab3 Ping r1 192.168.11.1: No return route
Lab3 Ping Lab2 192.168.11.101: No return route
r3 ping r2 192.168.22.1: Yes
r3 ping r2 192.168.11.2: No return route
r2 Ping r3 192.168.22.2: Yes
r2 Ping r3 192.168.33.1: Yes
r2 Ping Lab3 192.168.33.20: Yes
r2 Ping r1 192.168.11.1: Yes
r2 Ping Lab1 192.168.1.200: No return route
Lab2 ping Lab3 192.168.33.20: No route to host
Route all unknowns (including .11.0) through Router 1.
r2(config)#ip route 0.0.0.0 0.0.0.0 192.168.11.1
Show Commands
show ip route
