Lab
2.7.1 IP Unnumbered and Discontiguous Networks -- Configuring IP
Unnumbered
Objective:
Demonstrate how improper IP
addressing can have a negative impact on a network and the use of IP
Unnumbered on a point to point serial link to save IP addresses.
Background:
Your company obtained an outside
contractor to setup a basic network which would connect three
different areas of the company. These areas do not need to access
any other networks or the Internet. The resulting basic network is
shown above in the graphic. The network does not operate as
anticipated and it is your job to fix it.
Equipment:
Three Routers Three Switches Three
workstation
Step
1
Build the network in the above
diagram. Use RIP or IGRP as your routing protocol
Step
2
Turn on Debug All on Router-A Ping
S0/0 on Router-A from 168.71.8.2 workstation. Watch Router-A's
debug information.
What happened?
Step
3
Turn on Debug All on Router-C Ping
Ethernet 0/0 on Router-A from 168.71.8.2 workstation. Watch
Router-C's debug information.
What did you see?
Step
4
On Router-A type sh
ip route
On Router-B type sh
ip route
On Router-C type sh
ip route
Describe the journey of the ICMP
packets.
Step
5
Change the address on the
172.32.0.0 serial link so that the interfaces are in the
168.71.4.0 network.
Ping from the workstation on
network 168.71.5.0 to the workstation on 168.71.8.0
Were you successful?
Look at the routing tables Question
- Determine what is reachable on the overall network?
Step
6
Configure IP unnumbered on the serial
links.
On each serial interface enter
ip unnumbered fa 0/0 (or
correct ethernet port)
Will the workstations be able to
communicate?
List the entries in the routing
table
What is the main purpose of IP
unnumbered?
Step
7
Change the IP address of Ethernet0
on Router C to 168.71.8.17 255.255.255.240
Clear the routing table using the
command clear ip route *
Can the workstations communicate?
Why?
List the entries in the routing
table
What changed in the routing table
from step six to step seven?
Step
8
Change the IP Address of Ethernet
0 on Router C to 168.72.8.1 255.255.255.0
Clear the routing table using the
command clear ip route *
Can the workstations communicate?
Why?
Reflection:
Answer the following questions.
What benefit is gained by using IP
unnumbered?
How were the routers able to
successfully forward packets using IP unnumbered?
Challenge Exercise:
Can the five router lab from
semesters 1-4 be configured to support IP unnumbered?
Record the contents of the routing
table on one of the routers.
Configure the network to support
IP unnumbered.
Compare the contents of the
routing table using IP unnumbered to the routing table with
subnets on the links.
How many subnets have been saved?
How does the router know how to
forward packets on the network?