Lab 2.9.1 IP Helper Address

Objectives:

  • Demonstrate the use of the IP Helper Address command to pass broadcasts from a network.

Equipment Requirements:

  • Three Routers
  • Two Switches
  • One workstation
  • One DHCP Server

Preliminary:

Before programming the routers, make sure that the IOS version on the router supports Network Address Translation. Load a new IOS version if necessary. Construct the above network section using an appropriate routing protocol.

When construction of the network is complete, verify that routers can communicate and are sharing their routing tables. Also verify that the workstations are configured correctly for the network in which they reside.
For verification use the show ip route command, show interfaces command, show running-configuration command, ping, telnet, and any other relevant command(s).

Router configurations (interfaces subject to change based on routers used):

Router-A Router-B Router-C
FA0/0=168.71.5.1 S0/0=168.71.6.2 S0/1=168.71.7.2
S0/0=168.71.6.1 S0/1=168.71.7.1 FA0/0=168.71.8.1
SUBNET MASK 255.255.255.0

Scenario:

For this Lab we will be configuring IP helper on Router-A. Helper commands change broadcast addresses to a unicast address (an address of a single device on the network) so that the broadcast message can be routed to a specific destination, rather than everywhere. For our lab, we have a DHCP server on one subnet, but need it to give out IP addresses to another subnetwork. We do not have the funding for an additional DHCP server, so we must make the server that we have give out IP addresses from its current location.

Step 1

Build the network in the above diagram. Use RIP or IGRP as your routing protocol.

Step 2

Configure the DHCP Server with a pool of addresses that correspond to the addresses for the workstation.

Step 3

Set the workstation to obtain an IP address automatically

Did the workstation obtain an address? Explain.

Step 4

On router A use the IP helper address command with the network number that the DHCP server resides on.

Did the workstation obtain an IP address? Explain