LAB

IP Configuration using DHCP

Scenario 1 (One router and two subnets)

left (192.168.0.0/24) right (192.168.1.0/24)

Commands

• STEP 1: Configure the subnet “left” (PC0 computer):

– enable

– configure terminal

– ip dhcp pool left

– network 192.168.0.0 255.255.255.0

– dns-server 192.168.0.2

– default-router 192.168.0.1

– exit

– ip dhcp exclude-address 192.168.0.0 192.168.0.10

Commands

• STEP 2: Configure subnet “right” (PC1 computer):

– configure terminal

– ip dhcp pool left

– network 192.168.1.0 255.255.255.0

– dns-server 192.168.0.2

– default-router 192.168.1.1

– exit

– ip dhcp exclude-address 192.168.1.0 192.168.1.10

Commands

• STEP 3: Enable DHCP in computer PC0 and check

the assigned IP address.

• STEP 4: Enable DHCP in computer PC1 and check

the assigned IP address.

Report – Part 1

• Using the simulator, describe the sequence of DHCP

packet exchanged between PC0 and the router during

the IP assignment process.

• To start the test type in PC0:

• ipconfig /renew

• Indicate for each message:

• A) Source IP

• B) Destination IP

• C) Client Address (DHCP Protocol)

• D) Your Client (DHCP Protocol)

Report – Part 1 (Model)

Source Destination Source IP Destination

IP

Client

Address

Your Client

Address

Computer Router

Router Computer

Etc.

It is not necessary to include the messages propagated

through the switches

(DHCP messages are transparent to the switches)

Cenário 2 (Roteador e três subredes)

left (192.168.0.0/24) right (192.168.1.0/24)

far(192.168.2.0/24)

Relay Agent

• Routers don´t propagate broadcast messages

• However, it is possible to redirect DHCP messages

received in broadcast as unicast messages sent to

another IP in the network.

• In DHCP terminology, this function is called relay

agent.

Commands

• STEP 1: In router 0 include another pool of

addresses:

– configure terminal

– ip dhcp pool far

– network 192.168.2.0 255.255.255.0

– dns-server 192.168.0.2

– default-router 192.168.2.1

– exit

– ip dhcp exclude-address 192.168.2.0 192.168.2.10

Commands

• STEP 2: Assign IP addresses to the interface of router

3 as indicates in the figure.

• STEP 3: In router 3 configure the broadcast

redirection option on the Fa0/1 interface:

– configure terminal

– interface Fa0/2

– ip helper-address 192.168.1.1

– exit

Commands

• STEP 4: In router 0, add a static route to

192.168.2.0.

• STEP 5: In router 3, add a static route to

192.168.1.0.

• STEP 6: Enable DHCP in computer PC2, and

check the obtained IP address

Report – Part 2

• Using the simulator, describe the sequence of DHCP

packet exchanged between PC2 and the router during

the IP assignment process.

• To start the test type in PC2:

• ipconfig /renew

• Indicate for each message:

• A) Source IP

• B) Destination IP

• C) Client Address (DHCP Protocol)

• D) Your Client (DHCP Protocol)

Report – Part 2 (Model)

Source Destination Source IP Destination

IP

Client

Address

Your Client

Address

Computer Router

Router Computer

Etc.

It is not necessary to include the messages propagated

through the switches

(DHCP messages are transparent to the switches)