Network Routing

Configuring Complex Static Route

Let’s try out an example on static route configurations on a slightly more complex topology. There are 3 routers here; and we need to configure static routing on all 3 routers for full connectivity.

The Network Topology

Router0

First, we find out how many static routes to configure on Router0. There are 3 LANs in the topology. We only configure routes to the LAN that is not directly connected. To do so, we list out all the LAN destination:

LAN1 — directly connected, no routing needed
LAN2 — 1 hop away, need a static route to Router1
LAN3 — 1 hop away, need a static route to Router2

Now we need to configure two routes:

Route#(1): LAN1 →LAN2
Route#(2): LAN1 →LAN3

For Route#(1):

Parameters
==========
Network: 192.168.2.0
Destination Mask: 255.255.255.0
Next Hop IP: 200.1.1.2 on Router1
Command
=======
ip route 192.168.2.0 255.255.255.0 2001.1.2

For Route#(2), the parameters are:

Parameters
==========
Destination Network: 192.168.3.0
Destination Mask: 255.255.255.0
Next Hop IP: 200.1.1.3 on Router2
Command
=======
ip route 192.168.3.0 255.255.255.0 2001.1.3

Let’s find out how do we get the next hop IP here.

For Router0 to go from LAN1 to LAN2, The Next HOP is 200.1.1.2 at Router1

For Route#(1) — LAN1 going to LAN2. The packets from LAN1 goes to Router0. Router0 then forwards it to the next hop router, which is Router1. Router1 is chosen as next hop because it leads to LAN2. The next hop IP is the interface on Router1 that is facing towards Router0; which has the IP 200.1.1.2.

For Router0 to go from LAN1 to LAN3, The Next HOP is 200.1.1.3 at Router2

For Route#(2) — LAN1 going to LAN3. The packets from LAN1 goes to Router0. Router0 then forwards it to the next hop router, which is Router2. Router2 is chosen as next hop because it leads to LAN3. The next hop IP is the interface on Router2 that is facing towards Router0; which has the IP 200.1.1.3.

Router1

First, we find out how many static routes to configure on Router1. There are 3 LANs in the topology. We only configure routes to the LAN that is not directly connected. To do so, we list out all the LAN destination:

LAN1 — 1 hop away, need a static route to Router0
LAN2 — directly connected, no routing needed
LAN3 — 1 hop away, need a static route to Router2

Now we need to configure two routes:

Route#(1): LAN2 →LAN1
Route#(2): LAN2 →LAN3

For Route#(1):

Parameters
==========
Network: 192.168.1.0
Destination Mask: 255.255.255.0
Next Hop IP: 200.1.1.1 on Router0
Command
=======
ip route 192.168.1.0 255.255.255.0 2001.1.1

For Route#(2),

Parameters
==========
Destination Network: 192.168.3.0
Destination Mask: 255.255.255.0
Next Hop IP: 200.1.1.3 on Router2
Command
=======
ip route 192.168.3.0 255.255.255.0 2001.1.3

Let’s find out how do we get the next hop IP here.

Next hop from Router1 to Router0 (LAN2 →LAN1)

For Route#(1) — LAN2 going to LAN1. The packets from LAN2 goes to Router1. Router1 then forwards it to the next hop router, which is Router0. Router0 is chosen as next hop because it leads to LAN2. The next hop IP is the interface on Router0 that is facing towards Router1; which has the IP 200.1.1.1.

Next hop from Router1 to Router2 (LAN2 →LAN3)

For Route#(2) — LAN2 going to LAN3. The packets from LAN2 goes to Router1. Router1 then forwards it to the next hop router, which is Router2. Router2 is chosen as next hop because it leads to LAN3. The next hop IP is the interface on Router2 that is facing towards Router1; which has the IP 200.1.1.3.

Router2

First, we find out how many static routes to configure on Router2. There are 3 LANs in the topology. We only configure routes to the LAN that is not directly connected. To do so, we list out all the LAN destination:

LAN1 — 1 hop away, need a static route to Router0
LAN2 — 1 hop away, need a static route to Router1
LAN3 — directly connected, no need routing

Now we need to configure two routes:

Route#(1): LAN3 →LAN1
Route#(2): LAN3 →LAN2

For Route#(1):

Parameters
==========
Network: 192.168.1.0
Destination Mask: 255.255.255.0
Next Hop IP: 200.1.1.1 on Router0
Command
=======
ip route 192.168.1.0 255.255.255.0 2001.1.1

For Route#(2),

Parameters
==========
Destination Network: 192.168.2.0
Destination Mask: 255.255.255.0
Next Hop IP: 200.1.1.2 on Router2
Command
=======
ip route 192.168.2.0 255.255.255.0 2001.1.2

Let’s find out how do we get the next hop IP here.

Next hop from Router2 to Router0 (LAN3 →LAN1)

For Route#(1) — LAN3 going to LAN1. The packets from LAN3 goes to Router2. Router2 then forwards it to the next hop router, which is Router0. Router0 is chosen as next hop because it leads to LAN1. The next hop IP is the interface on Router0 that is facing towards Router2; which has the IP 200.1.1.1.

Next hop from Router2 to Router1 (LAN3 →LAN2)

For Route#(2) — LAN3 going to LAN2. The packets from LAN3 goes to Router2. Router2 then forwards it to the next hop router, which is Router1. Router1 is chosen as next hop because it leads to LAN2. The next hop IP is the interface on Router1 that is facing towards Router2; which has the IP 200.1.1.2.

Live Demo

Here’s the tutorial video to configure static routes on this network topology to connect LAN1, LAN2 and LAN3. You can get the demo network here for your own practice. You can download the latest Packet Tracer here.

Configuration Static Routes (Demo)

Note: if you typed static route wrongly, you can simply remove the route by adding the ‘no’ syntax in front of the route you want to delete.For example:

to remove 'ip route 192.168.3.0 255.255.255.0 200.1.1.3' 
type 'no ip route 192.168.3.0 255.255.255.0 200.1.1.3' 

To check your answer, download the completed network here.