Topic4-Part II Modules3-5.pdf

Part II Routing Protocols and Concepts 1 Part II Module 3: Configuring a Router 3.1 Configure a Router 3 3.1.1 CLI command modes 4 Two commands are used to restrict access to the privileged EXEC mode. “enable password” : The passwords are shown in clear text in the configuration files. “enable secre...

Part II Routing Protocols and Concepts 1 Part II Module 3: Configuring a Router 3.1 Configure a Router 3 3.1.1 CLI command modes 4 Two commands are used to restrict access to the privileged EXEC mode. “enable password” : The passwords are shown in clear text in the configuration files. “enable secret” : uses a strong MD5 algorithm for encryption 5 3.1.3 Configuring router passwords “service password-encryption”: It applies a weak encryption to all unencrypted passwords. The term “vty” stands for Virtual teletype. VTY is a virtual port and used to get Telnet or SSH access to the device. VTY is solely used for inbound connections 6 to the device. 3.1.4 Examining the show commands o show interfaces – Displays statistics for all interfaces on a router. : o show interfaces serial 0/1 o o o o o show clock - Shows the time set in the router show hosts - Displays a cached list of host names and addresses show users - Displays all users who are connected to the router show history - Displays a history of commands that have been entered show flash - Displays information about flash memory and what IOS files are stored there o show version - Displays information about the currently loaded software version along with hardware and device information. o show arp - Displays the ARP table of the router o show protocols - Displays the global and interface-specific status of any configured Layer 3 protocols o show startup-config - Displays the saved configuration located in NVRAM o show running-config - Displays the contents of the currently running configuration file or the configuration for a specific interface, or map class7 information. 3.1.5 Configuring a serial interface Router(config) # interface serial 0/0 Router(config-if) # clock rate 56000 Router(config-if) # no shutdown 8 3.1.7 Configuring an Ethernet interface 9 3.2 Finishing the Configuration 10 IOS file system overview Network components in memory 11 Making configuration changes 12 3.3 Other Configuration 13 Interface descriptions The “description” command 14 Login banners 15 Host name resolution Host names, unlike DNS names, are significant only on the router on which they are configured. 16 Part II Module 4: Learning about Other Devices 4.1 Discovering and Connecting to Neighbors 18 4.1.1 Introduction to CDP o Cisco Discovery Protocol (CDP) is used to obtain information about neighboring Cisco devices. o CDP Version 2 (CDPv2) is the most recent release of the protocol. o When a Cisco device boots up, CDP starts up automatically and allows the device to detect neighbor devices that use CDP. o CDP operates at the data link layer and allows two systems to learn about each other, even if they use different network layer protocols. o Each device that is configured for CDP sends periodic messages, which are known as advertisements, to directly connected Cisco devices 19 4.1.2 Information obtained with CDP Each router that uses CDP exchanges protocol information with its neighbors. The network administrator can display the results of this CDP information exchange on a console. 20 21 4.1.3 Implementation, monitoring, and maintenance of CDP The “cdp run” command is used to enable CDP globally on a router. By default, CDP is globally enabled. The “cdp enable” command is used to enable CDP on a particular interface. 22 23 24 25 26 4.1.5 Disabling CDP no cdp run cdp run 27 4.1.6 e-Lab Activity: CDP Neighbors 28 4.2 Getting Information about Remote Devices 29 4.2.1 Telnet 30 4.2.2 Establishing and verifying a Telnet connection To initiate a Telnet session any of the following alternatives can be used: Denver>connect paris Denver>paris Denver>131.108.100.152 Denver>telnet paris A hostname table or access to DNS for Telnet must be present for a name to work. Otherwise, the IP address of the remote router must be entered. A successful Telnet connection indicates that the upper-layer application functions properly. 31 4.2.3 Disconnecting and suspending Telnet sessions link UNIX 32 4.2.5 Alternative connectivity tests 33 34 Part II Module 5: Managing Cisco IOS Software 5.1 Router Boot Sequence and Verification 36 5.1.1 Stages of the router power-on boot sequence 37 5.1.2 How a Cisco device locates and loads IOS 38 5.1.3 Using the boot system command Boot IOS from flash memory 39 5.1.4 Configuration register The order in which the router looks for system bootstrap information depends on the boot field setting in the configuration register. The configuration register is a 16-bit register in NVRAM. The lowest four bits of the configuration register form the boot field. To ensure that the upper 12 bits are not changed, first use the show version command to retrieve the current values of the configuration register. Then use the config-register command and change only the value of the last hexadecimal digit 40 Router (config)#>config-register 0x2140 41 5.2 Managing the Cisco File System 42 5.2.1 IOS file system overview Network components in memory 43 A common set of prefixes 44 45 5.2.3 Managing configuration files using TFTP Why router use TFTP 46 5.2.4 Managing configuration files using copy and paste Copy Paste Another way to create a backup copy of the configuration is to capture the output of the 47 show running-config command. 5.2.7 Environment variables The IOS can also be restored from a TFTP session. The fastest way to restore an IOS image to the router is to use TFTP from ROMmon to download the image. To do this, set the environmental variables and then use the tftpdnld command. Assign variable by “=“ sign. E.g. type IP_ADDRESS=10.0.0.1 Use the set command to check the ROMmon environment variables. Once the 5 variables are set for the IOS download, the tftpdnld command is entered with no arguments. 48 49