In this lab, you will configure static routes between all three routers. This will allow your routers
to route packets so that all routers and all hosts will be able to reach (ping) each other. Once
your configuration is complete, you will use basic techniques to test your network’s connectivity.
Scenario
Three separate classful networks need routing between them and their subnets.
Questions:
What are the different classful networks?
1. ________________
2. ________________
3. ________________
4. ________________
5. ________________
Are there any subnets? If so, what are they?
1. _______________
2. _______________
3. _______________
4. _______________
5. _______________
Setup
Configure the cabling as shown in the network diagram
If the routers have a startup-config, erase it and perform a reload of the routers.
Important! Configure the routers to include hostnames and the proper interface
commands including IP addresses, subnet masks, etc. Each router should be able to
ping the interface of the adjacent (neighboring) router and the host on its LAN
(Ethernet) interface. Test and troubleshoot as necessary. Use the context sensitive
help, previous labs, your books and /or handouts and if your still having problems
ask your partner or ask the instructor for assistance.
Step 1 – Configuring Static Routes
On each router configure a separate and specific static route for each network or subnet. You do
not need to configure static routes for the router’s directly connected network(s) because like a
host, by configuring the IP address and subnet mask on an interface tells the router that it belongs
to that network/subnet.
Router1
Router1(config)# ip route 172.16.3.0 255.255.255.0 172.16.2.1
Router1(config)# ip route 192.168.2.0 255.255.255.0 192.168.1.1
Router2
Router2(config)# ip route 172.16.1.0 255.255.255.0 172.16.2.2
Router2(config)# ip route 192.168.1.0 255.255.255.0 172.16.2.2
Router2(config)# ip route 192.168.2.0 255.255.255.0 172.16.2.2
Router3
Router3(config)# ip route 172.16.1.0 255.255.255.0 192.168.1.2
Router3(config)# ip route 172.16.2.0 255.255.255.0 192.168.1.2
Router3(config)# ip route 172.16.3.0 255.255.255.0 192.168.1.2
Verify and Validate:
All hosts and all routers should be able to ping every interface in the network.
Do a “show running-config” and notice the static routes that you entered.
Router# show ip route
o What routes to networks do you see?
o Which routes are static and which routes are directly connected?
o What is the administrative distance for a static route?
o What is the administrative distance for a directly connected network?
Questions:
How does the next-hop-ip-address help with the routing process?
_____________________________________________.
Does it give the entire route, i.e., subnet mask?
_________________
What is it actually doing regarding the routing of the packet?
____________________________________________
How does a packet get from Host 2 to Host 3?
____________________________________________
____________________________________________
____________________________________________
Instead of a next-hop-ip-address, what else could you have used?
____________________________________________.
What would you need to do if you added new networks or deleted/modified existing
networks?
____________________________________________
____________________________________________
____________________________________________
Is there any way to summarize several static routes to multiple subnets into a single static
route?
_____________________________________________
_____________________________________________
_____________________________________________
Outputs
Router2#show ip route
(Output omitted)
Gateway of last resort is not set
172.16.0.0/24 is subnetted, 3 subnets
S 172.16.1.0 [1/0] via 172.16.2.2
C 172.16.2.0 is directly connected, Serial0
C 172.16.3.0 is directly connected, Ethernet0
S 192.168.1.0/24 [1/0] via 172.16.2.2
S 192.168.2.0/24 [1/0] via 172.16.2.2
Router1#show ip route
(output omitted)
Gateway of last resort is not set
172.16.0.0/24 is subnetted, 3 subnets
C 172.16.1.0 is directly connected, Ethernet0
C 172.16.2.0 is directly connected, Serial0
S 172.16.3.0 [1/0] via 172.16.2.1
C 192.168.1.0/24 is directly connected, Serial1
S 192.168.2.0/24 [1/0] via 192.168.1.1
Router3#show ip route
(Output omitted)
Gateway of last resort is not set
172.16.0.0/24 is subnetted, 3 subnets
S 172.16.1.0 [1/0] via 192.168.1.2
S 172.16.2.0 [1/0] via 192.168.1.2
S 172.16.3.0 [1/0] via 192.168.1.2
C 192.168.1.0/24 is directly connected, Serial0
C 192.168.2.0/24 is directly connected, Ethernet0
Step 2 – Configuring Summary Static Routes
The configuration of the routers in Step 1 works just great and is a valid way to configure routing
on these networks. Earlier, we noticed that the network 172.16.0.0 is divided into several
subnets. The Router3 router does not really need separate static routes for each subnet, since all
of the 172.16.0.0 subnets can be reached via the same next-hop-ip-address, i.e. Router1. Let’s
reconfigure the static routes on Router3 so that it only uses a single static route to reach all of the
172.16.0.0 subnets.
Router1
No changes
Router2
No changes
Router3
First, remove the current static routes:
Router3(config)# no ip route 172.16.1.0 255.255.255.0 192.168.1.2
Router3(config)# no ip route 172.16.2.0 255.255.255.0 192.168.1.2
Router3(config)# no ip route 172.16.3.0 255.255.255.0 192.168.1.2
Now, add the new summary static route:
Router3(config)# ip route 172.16.0.0 255.255.0.0 192.168.1.2
Verify and Validate:
All hosts and all routers should be able to ping every interface in the network.
Do a “show running-config” and notice the static routes that you entered.
Router3# show ip route
o What routes to networks do you now see?
Questions:
What made this new summary static route work for all subnets?
_____________________________________________________
_____________________________________________________
_____________________________________________________
Why is a single summary static route an advantage regarding the size of the routing
table?
_____________________________________________________
_____________________________________________________
_____________________________________________________
Why is a single summary static route an advantage regarding future changes to the
172.16.0.0 network?
_____________________________________________________
_____________________________________________________
_____________________________________________________
Outputs
Router3#show ip route
(Output omitted)
Gateway of last resort is not set
S 172.16.0.0/16 [1/0] via 192.168.1.2
C 192.168.1.0/24 is directly connected, Serial0
C 192.168.2.0/24 is directly connected, Ethernet0
Step 3 – Configuring Default Static Routes
Both Step 1 and Step 2 are acceptable ways to configure routing for these networks. We notice
that the 172.16.3.0/24 and the 192.168.2.0/24 networks are “stub networks,” meaning that there
is only one way out (both via Router1).
Router1
No changes
Router2
First, remove the current static routes:
Router2(config)# no ip route 172.16.1.0 255.255.255.0 172.16.2.2
Router2(config)# no ip route 192.168.1.0 255.255.255.0 172.16.2.2
Router2(config)# no ip route 192.168.2.0 255.255.255.0 172.16.2.2
Now, add the new default static route:
Router2(config)# ip route 0.0.0.0 0.0.0.0 172.16.2.2
Router3
First, remove the current static routes:
Router3(config)# no ip route 172.16.0.0 255.255.0.0 192.168.1.2
Now, add the new default static route:
Router3(config)# ip route 0.0.0.0 0.0.0.0 192.168.1.2
Verify and Validate:
All hosts and all routers should be able to ping every interface in the network.
Do a “show running-config” and notice the static routes that you entered.
Router2# show ip route
o What routes to networks do you now see?
Router3# show ip route
o What routes to networks do you now see?
Questions:
Do you think static routes are still used even with dynamic routing (RIP, OSPF, etc.)?
_______________. Hint: Think about the administrative distance.
Do you think default static routes are still used even with dynamic routing (RIP, OSPF,
etc.)?
_______________.
What is the disadvantage of doing this? How would a default static route be properly
used in a real world network? (How would a company’s network use a default route
when connecting to the Internet?)
________________________________________
________________________________________
________________________________________
Outputs
Router3#show ip route
(Output omitted)
Gateway of last resort is 192.168.1.2 to network 0.0.0.0
C 192.168.1.0/24 is directly connected, Serial0
C 192.168.2.0/24 is directly connected, Ethernet0
S* 0.0.0.0/0 [1/0] via 192.168.1.2
