www.ciscopress.com routers and routing basics ccna 2 chapter 3 1
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Routers and Routing Basics CCNA 2
Chapter 3
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Configuring a Router
Configuring a Router for Basic Routing Reviewing the Configuration Modes Configuring Ethernet and Serial Interfaces Configuring Hostnames and PasswordsExamining Operational Status Using show Commands Changing the Configuration
Documenting the Router ConfigurationConfiguring Interface DescriptionsConfiguring Login BannersConfiguring Local Host TablesBacking Up the Configuration
Summary
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Configuring a Router for Basic Routing
Internetwork with Two Routers Used in Basic Router Configuration
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Reviewing the Configuration Modes
Step 1 The user logs in from the console, moves to enable mode, and then enters configuration mode by using the configure terminal privileged mode EXEC command.
Step 2 The user changes the hostname using the hostname fred global configuration command.
Step 3 The user incorrectly tries to use the ip address 172.16.1.251 255.255.255.0 command. This command is an interface mode subcommand that must be issued from interface mode.
Step 4 The user moves to interface configuration mode using the interfaceFastethernet 0/0 command and then correctly uses the ip address interfacesubcommand.
Step 5 The user presses Ctrl-z to exit configuration mode, moving back to enable mode.
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Router Configuration Modes and Command Prompts
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Configuring Ethernet and Serial Interfaces
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Configuring Clock Rate on a Serial Link
• Clock rate command includes the speed in bits per second (bps), but a Router supports only specific speeds like 1200, 2400, 9600, 19,200, 38,400, 56,000, 64,000, 72,000, 125,000, 148,000, 500,000, 800,000, 100,0000, 1,300,000, 2,000,000, or 4,000,000 bps.
– It is set only on the DCE router
• Routers do not allow just any speed.
• For example, the clock rate 64000 command would be accepted, but the clock rate 65000 command would be rejected.
• To find the speeds supported on a particular type of router, use the clock rate ? command in serial interface configuration mode.
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Configuring Routes
Routing Tables on Routers R1 and R2—Connected Routes Only
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Configuring Routes(Continued)
Routing Tables on Routers R1 and R2—Connected Routes Only
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Summarizing the Working Configurations for R1 and R2
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Configuring a Router’s Hostname
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User and Enable Mode Passwords
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Console, Aux, VTY, and Enable Passwords
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Configuring Console, Aux, and VTY Passwords
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Two commands that can define the enable password
• If only one of the two commands (enable secret or enable password) is configured, but not both, IOS expects the user to enter the password as defined in that single configuration command.
• If both the enable secret and enable password commands are configured, the router expects the password as defined in the enable secret command. The router will not accept the password defined in the enable password command.
• If neither the enable secret nor enable password command is configured, the behavior varies. If the user is at the console, the router automatically allows the user access to enable mode. If the user is not at the console, the router rejects the enable command.
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Examining Operational Status Using show Commands
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Examining Operational Status Using show Commands (Continued)
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Examining Operational Status Using show Commands (Continued)
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Popular show commands
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Popular show commands(Continued)
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Changing the Configuration
• After configuration changes have been made, you should look at the running configuration using the show running-config command.
• For the simple changes reenter the command in the correct configuration mode.
• If a command was configured but was not needed, get into the same configuration mode and issue the same command prefaced by the word no.
What to Do if the Configuration Is Incorrect
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Changing the Configuration(Continued)
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Changing the Configuration(Continued)
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• To remove the password and login commands from the console line, use the word no in front.
– Router1(config-if)#Line con 0– Router1(config-line)#no password height– Router1(config-line)#no login
• Start over completely by erasing the startup-config file using the erase startup-config command and then reloading the router.
• Use copy startup-config running-config command or the copy tftp running-config command to copy the configuration file from a TFTP server, respectively, into the running-config file.
• Copy running-config startup-config command should be used to save a copy of the new configuration in the startup-config file in NVRAM.
Changing the Configuration(Continued)
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Documenting the Router Configuration
• The network should be well documented by the network engineers.
• Engineers should define a standard for their internetworks about how the routers (and switches) are configured.
• The creation of standards for network consistency helps
reduce network complexity, unplanned downtime, and events that may affect network performance.
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Configuring Interface Descriptions
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Configuring Interface Descriptions(Continued)
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Configuring Login Banners
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Configuring Local Host Tables
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Configuring Local Host Tables(Continued)
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Backing Up the Configuration
Movement of files using the copy command
between tree locations:
• The running configuration file in RAM
• The startup configuration file in NVRAM
• A TFTP server in the network
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Copying to TFTP Server
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Copying from TFTP Server
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Where to Keep the Backup Configuration Files
Three places in which you might want
to save the configuration files:
1. A TFTP server
2. A network (file) server
3. A disk in a safe place
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Command Summary for Copying and Looking at Configuration Files
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Configuration Command Summary
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Configuration Command Summary(Continued)
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Configuration Command Summary(Continued)
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