Note: This case study utilizes Packet Tracer. Please see the Chapter 5 Packet Tracer file located in Supplemental Materials.

Transcription

1 Note: This case study utilizes Packet Tracer. Please see the Chapter 5 Packet Tracer file located in Supplemental Materials. CHAPTER 5 OBJECTIVES Configure a router with an initial configuration. Use the Cisco Router and Security Device Manager (SDM) to configure a Cisco Integrated Services Router (ISR) with LAN connectivity, Internet connectivity and basic NAT. Configure a Cisco router for LAN connectivity, Internet connectivity and NAT using the Cisco IOS Command Line Interface (CLI) of the Cisco IOS software. Configure a WAN connection from a customer premise to an ISP. Describe, setup, and configure a stand alone LAN switch. Objective 1: Perform an Initial Router Configuration For this component, you will configure the passwords and hostname of the Anytown corporate office Cisco 1841 router that is used to connect to the Internet. The configuration will include encrypted passwords to control access to privileged EXEC mode. You will use Cisco IOS CLI commands. Step 1: Configure the router hostname. From the administrator PC, use the terminal emulation software to connect to the console of the Cisco 1841 ISR. Set the hostname on the router to Gateway. Step 2: Configure the privileged mode password and secret. In global configuration mode, set the password to cisco. Set the secret to cisco123. Step 3: Configure the console password. Set the password to cisco123, and require that the password be entered at login.

2 Step 4: Configure the vty password. Set the password to cisco123, and require that the password be entered at login. In privileged EXE mode, save the running configuration to the startup configuration. Step 5: Verify your configuration. Log out of the terminal session. Log in to the Cisco 1841 customer router. Enter the console password when prompted. Then navigate to privileged EXE mode. Enter the privileged EXE password when prompted. Step 6: Configuration questions: Which Cisco IOS CLI commands did you use most? How can you make the customer router passwords more secure? Objective 2: Configure the Serial and Ethernet Interfaces You will now configure the LAN Ethernet interface and the WAN Serial interface on the Gateway Cisco 1841 router: Step 1: Configure the LAN Ethernet interface. Describe the interface Connected to InternalLAN. Specify the IP address as /24. Ensure that the interface is enabled. Step 2: Verify your LAN interface configuration. Use the show run or show interfaces command to verify your configuration. Step 3: Configure the WAN serial interface. Identify the serial interface that you are configuring. Describe the interface Connected to ISP. Specify the interface's IP address and subnet mask /29. Ensure that the interface is enabled.

3 Step 4: Verify the LAN and WAN interface configurations. Use the ping command to verify connectivity to the WAN interface on the ISP router. Step 5: Save your configuration. Save the running configuration to the startup configuration. Step 6: Configuration questions: When you ping the LAN IP address of the ISP router, what happens and why? Which Cisco ISO CLI mode do you need to be in to configure the description of an interface? You configured the Fast Ethernet 0/0 interface with the command that brings the interface up and verified the configuration. However, when you rebooted the router, you find the interface is shut down. You now reconfigure the Fast Ethernet 0/0 interface and verify that the configuration works. What do you think is the most likely explanation for what you have seen? Objective 3: Configure a default route on the corporate router. You will now configure a default route on the Gateway Cisco 1841 router. The default route configuration uses the WAN serial port IP address on the Cisco 1841 ISP_router. Step 1: Verify lack of connectivity to the LAN IP address on the ISP router. How will you do this? Explain. Step 2: Configure the default route. Configure the default route to use the ISP WAN IP address as the next hop IP address. Step 3: Verify your LAN interface configuration. Which show command will you use to verify your configuration? Use the correct command to verify connectivity to the LAN IP address on the ISP router: Step 4: Save your configuration. Step 5: Configuration questions: You should now be able to access the entire ISP network. Note any issues and considerations about this configuration.

4 Is this type of access to the ISP LAN likely to happen in the real world? Why has this case study been configured to allow this type of access? Objective 4: Configure the Gateway Cisco 1841 ISR as a DHCP server In this component, you will configure the Cisco 1841 ISR router for the customer network by configuring the DHCP service. The corporate office has several computers that need to be automatically configured with IP addresses on the local subnet, and modified with the appropriate DHCP options to allow access to the Internet. The DHCP pool will be configured to use the /24 network but will have the first 49 addresses excluded. The default gateway and DNS server also need to be configured to and N.B. Packet Tracer does not currently support the Domain name and Lease period options. Consequently, these options are not used in this activity. Step 1: Configure the DHCP service. Create a DHCP pool called custompool. Define the network address range for the DHCP pool. Define the DNS server as Define the default gateway as Add an exclusion range of through to the DHCP pool. Step 2: Verify the DHCP configuration. From one of the corporate PC s ( computer1, 2 or 3 ) connected to the internal LAN, release the current IP address. Request a new IP address on the local network. Verify that the IP address has been correctly assigned by testing connectivity with the Ethernet port of the ISR router.

5 Step 3: Configuration questions: What is the purpose of DHCP on the customer network? What IP address is assigned to the computer you used after its IP address is renewed? What other DHCP options can be defined on the Cisco 1841 ISR router that are not configured in this activity? Objective 5: Configure Static NAT on a Cisco Router You will continue to configure the Cisco 1841 ISR router for the corporate network by configuring NAT. The customer needs to provide Internet access to just one employee. Because the internal network has been configured with a private address range, static NAT is needed to translate the internal computer out through a public WAN IP address. After configuring static NAT, you will verify the configuration using the corporate computer by testing connectivity to the ISP server. Step 1: Configure the static NAT. Configure the FastEthernet 0/0 interface as the inside NAT interface. Configure the Serial 0/0/0 interface as the outside NAT interface. Configure the static NAT mapping that maps the internal address to the external address. Step 2: Verifying the static NAT configuration. Type ping to see if the customer workstation connects to the customer DNS server. Step 3: Questions: What is the purpose of static NAT? What command is used to designate the inside interface for static NAT? What IP address does the server respond to when the customer workstation pings the Customer DNS server?

6 Objective 6: Backing Up a Cisco Router Configuration to a TFTP Server In this component, you will save the configuration of the Cisco 1841 ISR to a remote TFTP server. Backing up the configuration to the TFTP server is an important step in the setup of a Cisco router. Having the configuration backed up allows you to perform rapid recovery after hardware or configuration errors. It is important to save the running configuration to the startup configuration to protect the configuration from being lost on a router reload due to a power outage. After the running configuration is saved to the startup configuration, the startup configuration can be backed up to the TFTP server. The Corporate_Server is configured as the TFTP server that you will use to store the configuration of the Cisco 1841 ISR. Step 1: Save the running configuration to the startup configuration. Copy the running configuration to the startup configuration. Step 2: Back up the startup configuration to the TFTP server. Copy the startup configuration to the TFTP server at address Change the default name to Gateway Startup. From the Corporate_Server, click the Config tab and review the TFTP service. Verify that the Gateway_ Startup configuration is present in the list. Step 3: Questions: What are the consequences of reloading a router without saving the running configuration to the startup configuration? How is the backed up startup configuration used to recover from hardware failure in the Cisco 1841 ISR? What command would you use to back up the startup configuration to the TFTP server at IP address ?

7 Objective 7: Perform an Initial Switch Configuration You will now configure the corporate Internal_LAN Cisco Catalyst 2960 switch. The following parameters will be configured on the switch: Hostname Console password VTY password Privilege mode password Privilege mode secret IP address on VLAN1 interface Default gateway Step 1: Configure the switch hostname. Remove the serial connection from the administrator PC to the corporate router, and reconnect it to the 2960 switch. Use the correct cable and terminal emulation software to connect to the console of the switch. Set the hostname on the switch to Internal_LAN. Step 2: Configure the privileged mode password and secret. Configure the password to cisco. Configure the secret to cisco123. Step 3: Configure the console password. Set the console password to cisco and require the password to be entered at login. Step 4: Configure the VTY password. Set the password to cisco and require the password to be entered at login. Step 5: Configure an IP address on the interface VLAN1. Assign the IP address /24 to interface VLAN1, and activate it.

8 Step 6: Configure the default gateway. Assign the default gateway to Step 7: Questions: What is the significance of assigning the IP address to the VLAN1 interface instead of any of the FastEthernet interfaces? What command is necessary to enforce password authentication on the console and vty lines? How many gigabit ports are available on the Cisco Catalyst 2960 switch that were used in the case study? Objective 8: Map a Network using Cisco Discovery Protocol (CDP) Cisco Discovery Protocol (CDP) is a proprietary Layer 2 protocol that operates between Cisco devices such as routers and switches. CDP messages contain information about the device such as the device ID, platform type, connected interface, IOS version, and Layer 3 address. Only directly connected devices exchange information because CDP operates at Layer 2. In this section, you will examine the CDP show commands; and examine CDP configuration commands. Step 1: Enable CDP globally on a router and a switch. Log into the Gateway router from the administration machine and enable CDP globally. Now move the console cable to the Internal_LAN switch and do the same for the switch. Move back to the router and from the CLI on router issue the command that will show details of directly connected neighboring Cisco equipment. Do you see everything? If not, why not? Step 2: View CDP configuration settings. From the CLI on router Gateway, issue the command that will show its output timer and version information. Now issue the command that will enable you to see a list of the other CDP show commands. Finally, issue the command whose output shows timer information for all of the interfaces on the router. A specific interface may be specified to show timer information for that interface only.

9 Step 3: View CDP neighbor information. A router builds a table of information about neighboring devices from CDP messages received from those devices. At the router, reissue the command to show neighboring equipment. N.B: Packet Tracer operates in real time, like actual network equipment. If you do not see two entries in the output of the command, wait a couple of minutes and reissue the command until you do. Examine the output. A single line of information is displayed for each enabled and directly connected device. Issue the command that will show more detailed information about the switch. Step 4: Disable and enable CDP on an interface. You may not want to send CDP information to Cisco devices on an untrusted network. It is possible to disable CDP on a specific interface. From the CLI on the Gateway router disable CDP on the serial interface to the ISP. Step 5: Questions: Now that you have a basic understanding of CDP, be prepared to discuss any issues and considerations about CDP. For example: How could CDP be used to troubleshoot network connectivity issues? Is it likely that an ISP would have CDP configured on their gateway router? Objective 9: Configure a serial connection between a Customer Network and an ISP In this component, you will reconfigure the serial WAN interface to use a different IP address than the address that is already configured for the interface. The current serial WAN interface has been configured to use the default HDLC encapsulation. You will reconfigure the WAN to use PPP encapsulation to connect to the ISP. Note that this does imply that you will have to reconfigure the ISP router. This would NOT be normal practice! However, to make the study simpler, this will be performed.

10 Step1: Reconfigure the serial WAN interface. From the Administration PC, use the terminal utility to connect to the console of the Gateway router. Set the IP address on the serial interface to / 27. Set the encapsulation of the serial interface to PPP. Step 2: Verify the configuration. On the Gateway router, verify that the correct IP address, subnet mask, and encapsulation type are set for the serial 0/0/0 interface. What command is used? Step 3: Reconfigure the serial interface on the ISP router. Repeat step 1 on the ISP router, using an IP address of / 27. The secret password is cisco. Verify that the Gateway router can communicate with the ISP_Router over the serial WAN connection. Ping the WAN interface of the ISP_Router from the Gateway router. Step 4: Questions: What are the benefits of using the PPP encapsulation type instead of the default HDLC? Are there any other types of encapsulation that can be used on a serial link?