Chapter5ccna

Instructor & Todd Lammle Sybex CCNA 640-802 Chapter 5: Managing a Cisco Internetwork

Chapter 5 Objectives Cisco Router Components Boot Sequence Configuration register Backing up and restoring the IOS Backing up and restoring the configuration Cisco Discovery Protocol Telnet Resolving hostnames Troubleshooting tools

Cisco Router Components Bootstrap Brings up the router during initialization POST Checks basic functionality; hardware & interfaces ROM monitor Manufacturing testing & troubleshooting Mini-IOS Loads Cisco IOS into flash memory RAM Holds packet buffers, routing tables, & s/w Stores running-config

Cisco Router Components ROM Starts & maintains the router Flash Memory Holds Cisco IOS Not erased when the router is reloaded NVRAM Holds router (& switch) configurations Not erased when the router is reloaded Configuration Register Controls how the router boots up

Boot Sequence 1: Router performs a POST 2: Bootstrap looks for & loads the Cisco IOS 3: IOS software looks for a valid configuration file 4: Startup-config file (from NVRAM) is loaded If startup-config file is not found, the router will start the setup mode

Configuration Registers Register 16-bit software written into NVRAM Loads from flash memory & looks for the startup-config file Configuration Register Bits 16 bits read 15-0, from left to right default setting: 0x 2102 Register 2 1 0 2 Bit number 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Binary 0 0 1 0 0 0 0 1 0 0 0 0 0 0 1 0 NOTE: 0x means the digits that follow are in hexadecimal

Checking the Register Value Router#sh version Cisco Internetwork Operating System Software IOS ™ C2600 Software (C2600-I-M), Version 12.0(3)T3 RELEASE SOFTWARE (fc1) [output cut] Configuration register is 0x2102

Changing the Configuration Register Force the system into the ROM monitor mode Select a boot source & default boot filename Enable or disable the Break function Set the console terminal baud rate Load operating software from ROM Enable booting from a TFTP server

Changing the Configuration Register Router(config)#config-register 0x0101 Router(config)#^Z Router#sh ver Configuration register is 0x2102 (will be 0x0101 at next reload)

Recovering Passwords 1: Boot the router & interrupt the boot sequence by performing a break 2: Change the configuration register to turn on bit 6 (0x2142) 3: Reload the router 4: Enter the privileged mode 5: Copy the startup-config to running-config 6: Change the password 7: Reset the configuration register to the default value 8: Reload the router

Recovering Passwords 1: Boot the router & interrupt the boot sequence by performing a break using the Ctrl+Break key combination. You may need to upgrade your version of hyper-terminal in order for this to work successfully.

Recovering Passwords 2: Change the configuration register to turn on bit 6 (0x2142) rommon> confreg 0x2142 You must reset or power cycle for new config to take effect 3: Reload the router Type reset The router will reload & ask if you want to enter setup mode Answer NO 4: Enter the privileged mode Router> enable Router#

Recovering Passwords 5: Copy the startup-config to running-config Router# copy startup-config running-config 6: Change the password Router# config t Router(config)# enable secret cisco 7: Reset the configuration register to the default value Router(config)# config-register 0x2102 8: Reload the router

Backing up & Restoring the Cisco IOS Before you upgrade….. Copy the existing IOS to a TFTP host! Verify Flash Memory Router# sh flash System flash directory: File Length Name/status 1 8121000 c2500-js-1.112-18.bin [8121064 bytes used, 8656152 available, 16777216 total] 16384K bytes of processor board System flash (Read ONLY) Router#

Backing up the Cisco IOS #1: Ensure you have good connectivity to the TFPT host Router# ping 192.168.0.120 #2: Copy the IOS from flash to the TFTP host Router# copy flash tftp The TFTP host must have a default directory specified

Restoring or Upgrading the Cisco IOS #1: Ensure you have good connectivity to the TFTP host Router#ping 192.168.0.120 #2: Copy the IOS from the TFTP host to flash Router# copy tftp flash The TFTP host must have a default directory specified Copying the IOS from a TFTP host to flash requires a router reboot

Backing up the Configuration 1: Verify the Current Configuration Router# sh run 2: Verify the Stored Configuration Router# sh start Verify available memory 3: Copy running-config to NVRAM Router# copy run start Router# sh start 4: Copy running-config to a TFTP host Router# copy run tftp A second backup

Restoring the Configuration Used when… You need to copy the startup-config to the running-config Errors made in editing the running-config Changes made at the TFTP host need to be copied to the running-config or startup-config Router# copy tftp run or Router# copy tftp start NOTE: The configuration file is ASCII. Any text editor will enable changes Erasing the Configuration Router# erase startup-config Note: When the router reboots it will be in setup mode

Using Cisco Discovery Protocol (CDP) A Cisco proprietary protocol Designed to collect information about directly attached & remote devices Hardware information Protocol information Useful in troubleshooting & documenting the network

Getting CDP Timers & Holdtime Information Configuration CDP Timer: How often CDP packets are transmitted to all active interfaces CDP Holdtime: The amount of time that the device will hold packets received from neighbor devices Router# sh cdp Global CDP information Sending CDP packets every 60 seconds Sending a holdtime value of 180 seconds Router# config t Router(config)# cdp timer 90 Router(config)# cdp holdtime 240

Getting Neighbor Information Shows information about directly connected devices CDP packets are not passed through a Cisco switch Can only see what is directly attached Router# sh cdp nei or Router# sh cdp neighbor detail Detailed information; hostname, IP address, etc

Getting Interface Traffic & Port Information Interface Traffic Information: CDP packets sent & received Errors with CDP Router# sh cdp traffic Port & Interface Information: Encapsulation on the line Timer & Holdtime for each interface Router# sh cdp interface

Using Telnet A virtual terminal protocol Part of the TCP/IP suite Allows connections to remote devices Gather information Run programs Note: The VTY passwords must be set on the routers

Using Telnet Setting VTY passwords: Router# config t Router(config)# line vty 0 4 Router(config)# login Router(config)# password cisco Router(config)#^ Z Router# 172.16.10.2 Trying 172.16.10.2 … Open User Access Verification Password: RouterB>

Using Telnet Setting VTY password: Router# config t Router(config)# line vty 0 4 Router(config)# login Router(config)# password cisco Router(config)#^ Z Router# 172.16.10.2 Trying 172.16.10.2 … Open User Access Verification Password: RouterB> Remember…. VTY password is the user mode (>) password - not the enable mode (#) password With no enable/enable secret password set, the following happens: RouterB> en % No password set RouterB> This equates to good security!

Telnet Commands Telnetting into Multiple Devices Ctrl+Shift+6 (release) X Checking Telnet Connections Router# sh sessions Checking Telnet Users Router# sh users Closing Telnet Sessions RouterB> exit RouterB> disconnect

Resolving Hostnames To use a hostname rather than an IP address to connect to a remote host a device must be able to translate the hostname to an IP address Build a host table on each router Build a Domain Name System (DNS) server

Building a Host Table Provides name resolution only on the router on which it is built [ip host name tcp_port_number ip_address] Router(config)# ip host RouterB 172.16.10.2 Router(config)# ip host switch 192.168.0.148 Router# sh hosts Default TCP port number: 23 Router# RouterB RouterB#(Ctrl+Shift+6) ( X ) Router# switch

Using DNS to Resolve Names Used when you have many devices on your network Making DNS work… ip domain-lookup Turned on by default ip name-server Sets the IP address of the DNS server (up to 6 each) ip domain-name Appends the domain name to the hostname Ex: RouterA.neversail.navy.mil

Checking Network Connectivity Ping Displays the minimum, average, & maximum times it takes for aping packet to find a specified system + return Router# ping RouterB Trace Shows the path a packet takes to get to a remote device Router# trace RouterB

Summary Go through all the written and review questions Go through the answers with the class

Chapter5ccna

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