CCNA RSE Lab: 8.1.2.5 Configuring Basic DHCPv4 on a Switch

CCNA RSE Lab: 8.1.2.5 Configuring Basic DHCPv4 on a Switch

Topology

Addressing Table

Device Interface IP Address Subnet Mask
R1 G0/1 192.168.1.10 255.255.255.0
Lo0 209.165.200.225 255.255.255.224
S1 VLAN 1 192.168.1.1 255.255.255.0
VLAN 2 192.168.2.1 255.255.255.0

Objectives
Part 1: Build the Network and Configure Basic Device Settings

Part 2: Change the SDM Preference

  • Set the SDM preference to lanbase-routing on S1 .

Part 3: Configure DHCPv4

  • Configure DHCPv4 for VLAN 1 .
  • Verify DHCPv4 and connectivity.

Part 4: Configure DHCP for Multiple VLANs

  • Assign ports to VLAN 2.
  • Configure DHCPv4 for VLAN 2.
  • Verify DHCPv4 and connectivity.

Part 5: Enable IP Routing

  • Enable IP routing on the switch.
  • Create static routes.

Background / Scenario
A Cisco 2960 switch can function as a DHCPv4 server. The Cisco DHCPv4 server assigns and manages IPv4 addresses from identified address pools that are associated with specific VLANs and switch virtual interfaces (SVIs). The Cisco 2960 switch can also function as a Layer 3 device and route between VLANs and a limited number of static routes. In this lab, you will configure DHCPv4 for both single and multiple VLANs on a Cisco 2960 switch, enable routing on the switch to allow for communication between VLANs, and add static routes to allow for communication between all hosts.

Note: This lab provides minimal assistance with the actual commands necessary to configure DHCP. However, the required commands are provided in Appendix A. Test your knowledge by trying to configure the devices without referring to the appendix.

Note: The routers used with CCNA hands-on labs are Cisco 1 941 Integrated Services Routers (ISRs) with Cisco IOS Release 1 5.2(4)M3 (universalk9 image). The switches used are Cisco Catalyst 2960s with Cisco IOS Release 1 5.0(2) (lanbasek9 image). Other routers, switches and Cisco IOS versions can be used. Depending on the model and Cisco IOS version, the commands available and output produced might vary from what is shown in the labs. Refer to the Router Interface Summary Table at the end of this lab for the correct interface identifiers.

Note: Make sure that the router and switches have been erased and have no startup configurations. If you are unsure, contact your instructor.

Instructor Note: Refer to the Instructor Lab Manual for the procedures to initialize and reload devices.

Required Resources

  • 1 Router (Cisco 1941 with Cisco IOS Release 15.2(4)M3 universal image or comparable)
  • 2 Switches (Cisco 2960 with Cisco IOS Release 15.0(2) lanbasek9 image or comparable)
  • 2 PCs (Windows 7, Vista, or XP with terminal emulation program, such as Tera Term)
  • Console cables to configure the Cisco IOS devices via the console ports
  • Ethernet cables as shown in the topology
Part 1: Build the Network and Configure Basic Device Settings

Step 1: Cable the network as shown in the topology.
Step 2: Initialize and reload the router and switches.
Step 3: Configure basic setting on devices.
a. Console into the router and enter global configuration mode.
b. Copy the following basic configuration and paste it to the running-configuration on the router.

c. Console into the switches and enter global configuration mode.
d. Copy the following basic configuration and paste it to the running-configuration on the switches.

e. Assign device names as shown in the topology.
f. Configure the IP addresses on R1 G0/1 and Lo0 interfaces, according to the Addressing Table.
g. Configure the IP addresses on S1 VLAN 1 and VLAN 2 interfaces, according to the Addressing Table.
h. Save the running configuration to the startup configuration file.

Part 2: Change the SDM Preference

The Cisco Switch Database Manager (SDM) provides multiple templates for the Cisco 2960 switch. The templates can be enabled to support specific roles depending on how the switch is used in the network. In this lab, the sdm lanbase-routing template is enabled to allow the switch to route between VLANs and to support static routing.

Step 1: Display the SDM preference on S1.
On S1 , issue the show sdm prefer command in privileged EXEC mode. If the template has not been changed from the factory default, it should still be the default template. The default template does not support static routing. If IPv6 addressing has been enabled, the template will be dual-ipv4-and-ipv6 default.

What is the current template?
Answers will vary. “default” or “dual-ipv4-and-ipv6 default” or “lanbase-routing”.

Step 2: Change the SDM Preference on S1.
a. Set the SDM preference to lanbase-routing. (If lanbase-routing is the current template, please proceed to Part 3.) From global configuration mode, issue the sdm prefer lanbase-routing command.

Changes to the running SDM preferences have been stored, but cannot take effect until the next reload. Use ‘show sdm prefer’ to see what SDM preference is currently active.

Which template will be available after reload? __________________________________ lanbase-routing

b. The switch must be reloaded for the template to be enabled.

Note: The new template will be used after reboot even if the running configuration has not been saved. To save the running configuration, answer yes to save the modified system configuration.

Step 3: Verify the lanbase-routing template is loaded.
Issue the show sdm prefer command to verify that the lanbase-routing template has been loaded on S1.

Part 3: Configure DHCPv4

In Part 3, you will configure DHCPv4 for VLAN 1, check IP settings on host computers to validate DHCP functionality, and verify connectivity for all devices in VLAN 1 .

Step 1: Configure DHCP for VLAN 1 .
a. Exclude the first 10 valid host addresses from network 192.168.1.0/24. Write the command you used in the space provided.

b. Create a DHCP pool named DHCP1 . Write the command you used in the space provided.

c. Assign the network 192.168.1.0/24 for available addresses. Write the command you used in the space provided.
____________________________________________________________________________________

d. Assign the default gateway as 192.168.1.1. Write the command you used in the space provided.

e. Assign the DNS server as 192.168.1.9. Write the command you used in the space provided.

f. Assign a lease time of 3 days. Write the command you used in the space provided.

g. Save the running configuration to the startup configuration file.

Step 2: Verify DHCP and connectivity.
a. On PC-A and PC-B, open the command prompt and issue the ipconfig command. If IP information is not present, or if it is incomplete, issue the ipconfig /release command, followed by the ipconfig /renew command. For PC-A, list the following:

IP Address: _________________________________________ 192.168.1.11
Subnet Mask: ________________________________________ 255.255.255.0
Default Gateway: _____________________________________ 192.168.1.1
For PC-B, list the following:
IP Address: _________________________________________ 192.168.1.12
Subnet Mask: ________________________________________ 255.255.255.0
Default Gateway: _____________________________________ 192.168.1.1

b. Test connectivity by pinging from PC-A to the default gateway, PC-B, and R1 .

From PC-A, is it possible to ping the VLAN 1 default gateway? __________ Yes
From PC-A, is it possible to ping PC-B? __________ Yes
From PC-A, is it possible to ping R1 G0/1? __________ Yes
If the answer is no to any of these questions, troubleshoot the configurations and correct the error.

Part 4: Configure DHCPv4 for Multiple VLANs

In Part 4, you will assign PC-A to a port accessing VLAN 2, configure DHCPv4 for VLAN 2, renew the IP configuration of PC-A to validate DHCPv4, and verify connectivity within the VLAN.

Step 1: Assign a port to VLAN 2.
Place port F0/6 into VLAN 2. Write the command you used in the space provided.

Step 2: Configure DHCPv4 for VLAN 2
a. Exclude the first 10 valid host addresses from network 192.168.2.0. Write the command you used in the space provided.

b. Create a DHCP pool named DHCP2. Write the command you used in the space provided.

c. Assign the network 192.168.2.0/24 for available addresses. Write the command you used in the space provided.

d. Assign the default gateway as 192.168.2.1 . Write the command you used in the space provided.

e. Assign the DNS server as 192.168.2.9. Write the command you used in the space provided.

f. Assign a lease time of 3 days. Write the command you used in the space provided.

g. Save the running configuration to the startup configuration file.

Step 3: Verify DHCPv4 and connectivity.

a. On PC-A, open the command prompt and issue the ipconfig /release command, followed by ipconfig /renew command.
For PC-A, list the following:

IP Address: _________________________________________ 192.168.2.11
Subnet Mask: ________________________________________ 255.255.255.0
Default Gateway: _____________________________________ 192.168.2.1

b. Test connectivity by pinging from PC-A to the VLAN 2 default gateway and PC-B.

From PC-A, is it possible to ping the default gateway? __________ Yes

From PC-A, is it possible to ping PC-B? __________ No

Were these pings successful? Why?
Because the default gateway is in the same network as PC-A, PC-A can ping the default gateway. PC-B is in a different network; therefore, the ping from PC-A is not successful.

c. Issue the show ip route command on S1.

What was the result of this command?
No default gateway has been set and no routing table is present on the switch.

Part 5: Enable IP Routing

In Part 5, you will enable IP routing on the switch, which will allow for inter-VLAN communication. For all
networks to communicate, static routes on S1 and R1 must be implemented.

Step 1: Enable IP routing on S1.
a. From global configuration mode, use the ip routing command to enable routing on S1.

b. Verify inter-VLAN connectivity.
From PC-A, is it possible to ping PC-B? __________ Yes

What function is the switch performing?
The switch is routing between VLANs.

c. View the routing table information for S1.

What route information is contained in the output of this command?
The switch exhibits a routing table showing VLANs as directly connected networks 192.168.1.0/24 and 192.168.2.0/24.

d. View the routing table information for R1.

What route information is contained in the output of this command?
The router output shows directly connected networks of 192.168.1.0 and to 209.165.200.224 but has no entry for the 192.168.2.0 network.

e. From PC-A, is it possible to ping R1? __________ No
From PC-A, is it possible to ping Lo0? __________ No

Consider the routing table of the two devices, what must be added to communicate between all networks?
In order for communication to occur between all networks, routes must be added to the routing tables.

Step 2: Assign static routes.
Enabling IP routing allows the switch to route between VLANs assigned on the switch. For all VLANs to communicate with the router, static routes must be added to the routing table of both the switch and the router.

a. On S1, create a default static route to R1 . Write the command you used in the space provided.

b. On R1, create a static route to VLAN 2. Write the command you used in the space provided.

c. View the routing table information for S1.

How is the default static route represented?
Gateway of last resort is 192.168.1.10 to network 0.0.0.0

d. View the routing table information for R1.

How is the static route represented?
S 192.168.2.0/24 is directly connected, GigabitEthernet0/1

e. From PC-A, is it possible to ping R1? __________ Yes
From PC-A, is it possible to ping Lo0? __________ Yes

Reflection
1. In configuring DHCPv4, why would you exclude the static addresses prior to setting up the DHCPv4 pool?
If the static addresses were excluded after the DHCPv4 pool was created, a window of time exists where the excluded addresses could be given out dynamically to hosts.

2. If multiple DHCPv4 pools are present, how does the switch assign the IP information to hosts?
The switch will assign IP configurations based on the VLAN assignment of the port to which the host is connected.

3. Besides switching, what functions can the Cisco 2960 switch perform?
The switch can function as a DHCP server and can perform static and inter-VLAN routing

Router Interface Summary Table

Router Interface Summary

Router Model Ethernet Interface #1 Ethernet Interface #2 Serial Interface #1 Serial Interface #2
1800 Fast Ethernet 0/0
(F0/0)
Fast Ethernet 0/1
(F0/1)
Serial 0/0/0 (S0/0/0) Serial 0/0/1 (S0/0/1)
1900 Gigabit Ethernet 0/0
(G0/0)
Gigabit Ethernet 0/1
(G0/1)
Serial 0/0/0 (S0/0/0) Serial 0/0/1 (S0/0/1)
2801 Fast Ethernet 0/0
(F0/0)
Fast Ethernet 0/1
(F0/1)
Serial 0/1 /0 (S0/1 /0) Serial 0/1 /1 (S0/1 /1)
2811 Fast Ethernet 0/0
(F0/0)
Fast Ethernet 0/1
(F0/1)
Serial 0/0/0 (S0/0/0) Serial 0/0/1 (S0/0/1)
2900 Gigabit Ethernet 0/0 (G0/0) Gigabit Ethernet 0/1 (G0/1) Serial 0/0/0(S0/0/0) Serial 0/0/1 (S0/0/1)
Note: To find out how the router is configured, look at the interfaces to identify the type of router and how many interfaces the router has. There is no way to effectively list all the combinations of configurations for each router class. This table includes identifiers for the possible combinations of Ethernet and Serial interfaces in the device. The table does not include any other type of interface, even though a specific router may contain one. An example of this might be an ISDN BRI interface. The string in parenthesis is the legal abbreviation that can be used in Cisco IOS commands to represent the interface.

Appendix A: Configuration Commands

Configure DHCPv4

Configure DHCPv4 for Multiple VLANs

Enable IP RoutingS1(config)# ip routing

Device Configs
Router R1

Switch S1

More Resources

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Prasanna

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