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CN2668 Routers and Switches

This detailed guide covers the essential steps for configuring and managing Cisco routers, focusing on the startup process and various configuration tasks. It outlines the boot sequence, including hardware tests and loading the Cisco IOS. Learn how to manage configuration files, implement changes, and verify settings using commands like `show startup-config`, `show running-config`, and `ping`. Discover how to manually configure IP addresses, utilize Telnet for remote access, and leverage tools like the Cisco Discovery Protocol (CDP) for enhanced device discovery.

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CN2668 Routers and Switches

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  1. CN2668Routers and Switches Kemtis Kunanuraksapong MSIS with Distinction MCTS, MCDST, MCP, A+

  2. Agenda • Chapter 6: Router Startup and Configuration • Exercise • Quiz

  3. Router Startup • In general, the boot process follows these steps: • Test hardware (POST) • Load the bootstrap program • Locate and load the Cisco IOS • Locate and load the router configuration file • See Figure 6-1 on Page 146

  4. Test Hardware (POST) • ROM in a router contains • The power-on self-test (POST) • The bootstrap program • A version of the operating system • During the POST, the ROM Monitor checks the configuration register for instructions regarding how to load the Cisco IOS

  5. Router Configuration Files • startup-config (backup configuration) • The router configuration file that loads during the boot process • To revert to the settings in your startup-config • Reboot the system by powering the router off and back on again • Issue the reload command at the privileged EXEC mode prompt

  6. Router Configuration Files • To view the contents of the startup-config • Type show start-upconfigor show start at the enable prompt • To see your working or running configuration • Type show running-config or just show run at the enable prompt • See command in Table 6-1 on Page 148

  7. Methods for Making Changes • Basic steps to implement changes: • Make changes as desired to the configuration • Examine those changes • Determine if the changes meet the desired result • Remove the changes if they do not meet the desired result, or simply reboot the router • Copy the changes from the running configuration to the startup configuration when they do meet the desired result

  8. IP on the Router • To manually configure IP on an interface • Change to interface configuration mode • Use the ip address command to configure an IP address for the specific interface • To configuring a serial interface as a DCE (data communication equipment) • You will also need to add the clockrate [bandwidth in bits per second] command

  9. Telnet • Utility that connects at the application layer and provides remote access to other devices • Cisco routers allow telnet connections via their virtual terminal ports

  10. IP Host Names • To determine the address to name mapping on your router, type: router#show hosts • To add an entry to your hosts file • Go to global configuration mode and type: router(config)#ip host router15 192.168.5.1 • To remove that entry, type: router(config)#no ip host router15 192.168.5.1 • To allow a name server to handle the IP address to name resolution, type: router(config)#ip name-server 172.33.44.1

  11. Ping and Trace • To verify connectivity at the Internetwork layer of the TCP/IP model • Ping can return the following replies: ! Successful receipt of the ICMP echo . Request timed out U Destination was unreachable C Congestion experienced I Ping interrupted ? Packet type unknown & Packet TTL exceeded

  12. Ping and Trace (continued) • Using the ping command alone • Allows you to enter your ping command step by step ( specify protocol type, size of packet, etc) • Trace sends multiple ICMP packets with progressively higher time-to-live counters (TTL) • Until the packet reaches the destination

  13. Ping and Trace (continued) • The following responses can be returned by a trace: !H Indicates that a router received, but did not forward, the ICMP echo request P Protocol unreachable N Network unreachable U Port unreachable * Request timed out

  14. IP Route • Issue the show ip route command from the enable mode prompt • To display the routing table • Typically, routing tables are dynamically created when routing protocols are configured on the router • If you want, you can use the ip route command from the global configuration mode • To statically enter routes in the routing table

  15. Checking the Interface • show interfaces command • Check the configuration of a specific interface from the enable mode prompt • Example: router#showint s0/0 • Replies • Serial0/0 is up, line protocol is up • Serial0/0 is up, line protocol is down • The interface is up, but no packet received • Serial0/0 is up, line protocol is administratively down • Required no shutdown to bring the interface up • Serial0/0 is down, line protocol is down

  16. Checking the Interface (continued) • Clear counters • The router keeps detailed statistics regarding data passing across its interfaces • To clear the counters for interface f0/0, type: router#clear interface f0/0 • debug command • One of the most powerful tools you can use to obtain information from your router • Tool is only available from privileged EXEC mode

  17. Cisco Discovery Protocol (CDP) • Cisco proprietary Data Link layer protocol • Shares configuration information between Cisco devices that are connected directly to each other • All Cisco devices can use CDP to: • Discover each other • Learn about the configurations of other devices • Using CDP can help you quickly determine the network topology • See Figure 6-4 on Page 155 • CDP was designed to be a low-overhead protocol

  18. Cisco IOS • Cisco IOS is usually loaded from flash memory • If the router cannot find the IOS in flash memory, it will look for a copy on a TFTP server • If it cannot find one there, it will boot a minimal version of the IOS from ROM • If you want to see information about your router’s flash memory: • Type show flash from the enable mode prompt

  19. Configuration Register • Every Cisco router has a 16-bit configuration register, which is stored in NVRAM • This register allows you to control several boot functions: • Forcing the system into the bootstrap program • Enabling or disabling the console Break function • Setting the console terminal baud rate • Loading the IOS from ROM • Loading the IOS from a TFTP server • Examine the configuration register by typing show version

  20. ROM Monitor Mode • The bootstrap program that is built into the firmware of the router • Used to initialize the hardware and load the IOS • To perform other tasks such as diagnostics and recovering passwords • Configure your system to enter ROM Monitor mode • Enter the following command at the global configuration prompt: router(config)#config-register 0x2100

  21. ROM Monitor Mode (continued) • Configure your system to boot a smaller IOS image from ROM and enter RxBoot mode • Enter the following command at the global configuration prompt: router(config)#config-register 0x2101

  22. RxBoot Mode • A limited version of the IOS • Boot into this mode: • When you want to access a TFTP server to download a new IOS • If your router enters RxBoot mode without your intervention • Indicates that the router could not find a good IOS image • Prompt: router(boot)

  23. Boot System Commands • As long as the configuration register is configured with a 2 as the final hexadecimal digit • The ROM Monitor will look for boot system commands in NVRAM during the bootup process • Enable your system to boot an IOS file from the TFTP server • From global configuration mode: router(config)#boot system tftp somefile.bin

  24. Backing Up and Restoring the IOS • copy flash tftp • The command for backing up your IOS to a TFTP server • You will be asked for the source filename, the IP address of the TFTP server, and the destination filename • Type erase flash at the privileged EXEC mode prompt • To erase the IOS

  25. Upgrading the IOS • Before you load a new IOS file to your router • Use the show flash command to ensure there is enough free memory to hold it • The system will tell you how much memory is used and how much is free • If there is not enough memory to hold both the current IOS image and the upgrade • You will have to erase the existing flash memory as previously mentioned

  26. Router Password Recovery • Password recovery • You must be physically connected to the router using the console cable • Steps to perform password recovery on the Cisco 2600 series: • Follow the steps on Page 161 - 162

  27. Security Device Manager • A Web-based tool primarily used for implementing and testing security configurations • To configure routing protocols, WAN services, wireless routing, firewalls, virtual private networks (VPNs), and quality of service (QoS) • SDM is typically not used to configure basic functionality on a Cisco router • See Figure 6-8 on Page 162

  28. Assignment • Review Questions • 1 – 25 • Lab 6.1 – 6.5

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