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Chapter 4. Introduction to the Cisco IOS. Cisco Internetwork Operating System (IOS). Most Cisco stuff runs on same OS Uses command line interface (CLI) Handles protocols and functions Controls security Scaleable Reliable. Connecting to a Cisco Router.
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Chapter 4 Introduction to the Cisco IOS
Cisco Internetwork Operating System (IOS) • Most Cisco stuff runs on same OS • Uses command line interface (CLI) • Handles protocols and functions • Controls security • Scaleable • Reliable
Connecting to a Cisco Router • Configure router, verify configuration, check statistics • Three ways to connect: • Console port, often used first to set up router (RJ-45 jack) • Auxiliary port for modem access (RJ-45) • Telnet to any active interface • Serial interfaces for WANs, AUI for Ethernet
Bringing up a Router • Power on self-test (POST) • Then, loads Cisco IOS from flash memory • Flash memory is electronically erasable programmable read only memory (EEPROM) • IOS loads and looks for startup-config file in nonvolatile RAM (NVRAM) • No startup-config? Then router enters setup mode for you to configure it
Setup Mode • Basic Management Setup to get the thing started and allow connectivity • Extended Setup to configure global parameters and each interface • Defaults are provided in [ ] • Or, use Command-Line Interface • Don’t enter the initial configuration dialog • Router then checks all interfaces • Router then sits at prompt and waits for you
Passwords Can Be Confusing • enable secret is password to get into configurations • enable password is older version, you can set it and not use it ever again if enable secret is set • virtual terminal password is used when telnetting to router (must have one before telnet is allowed)
The Interfaces • Can set: • duplex mode • IP address • Subnet mask • Router then displays your settings • Choosing not to configure during bootup brings you to CLI
Logging into the Router • User mode: • Router> • Used mostly to view statistics • Router> logout exits • Router> enable enters privileged mode • Privileged mode: • Router# • Used to view & change router configuration • Router# disable goes back to user mode • Router# logout exits
Overview of Router Modes • Global changes: • config terminal or config t • Changes made to running-config (DRAM) • To change the startup-config (NVRAM) • config memory or config mem Note: Any configuration changes need to be placed into RAM. Typing config mem or config net (from a TFTP host) will replace the current running-config
Configuration and CLI Prompts • Global configuration prompt • Router(config)# • Interfaces • Router(config-if)# • Sub-interfaces • Router(config-subif)# • Line Commands • Router(config-line)# • Routing Protocol Configurations • Router(config-router)#
Editing & Help Features • Commands starting with a certain letter Router#c? clear clock configure connect copy • Router# clock ? shows next options for clock • Enhanced editing commands on pp. 161-162 • Router-command history shows recent commands used (p. 162) • show history (last 10 commands) • Gathering Basic Routing Information • show version
Hands-On Labs 4.1- 4.2 Pages 192-194
Setting the Passwords • 5 passwords: • 1st two used to set your enable password • Used to secure privileged mode; Router>enable • Other three are used to configure a password in user mode via: • console port • auxiliary port • Telnet
Passwords • Enable passwords Router(config)#enable password cisco Router(config)#enable secret cisco • Auxiliary password • Console password • Telnet Password (must be set before telnet allowed) • Router# sh run will display passwords! To encrypt: Router(config)#service password-encryption
Hands-On Labs 4.3- 4.4 Pages 194-196
Banners • Users & admins see them when logging in • Types • exec • incoming • login • Message of the day (motd) is most common, displays for all users arriving on any port • Notice delimiting character
Router Interfaces • Routers have interfaces to connect networks: serial, ethernet, fast ethernet • How to set interfaces? • Router# show int e0 lets you check check status of Ethernet interface • Router# config t enters configuration mode • Router(config)# int e0 to work with Ethernet interface • Router(config-if)# no shutdown brings it up • Router(config-if)# shutdown takes it down
Setting IP Address • Configuring an IP address on an interface: • Router(config)#int e0 • Router(config-if)#ip address 172.16.10.2 255.255.255.0 • Router(config-if)#no shut
Serial Interfaces • Serial interfaces usually are DTE and connect to CSU/DSU, which is the DCE • CSU/DSU usually provides the clocking • In a lab, one router will be DTE and the other will be DCE • Router(config)# int s0 • Router(config-if)# clock rate 64000 • Clock rate is in bits per second • Set bandwidth for routing protocols to use: • Router(config-if)# bandwidth 64 • Bandwidth is in KB per second
Hostnames & Descriptions • Hostnames locally significant (not used as network name) Router(config)# hostname todd todd(config)# • Descriptions can make printouts easier to read (see page 205) Atlanta(config)# int e0 Atlanta(config-if)# description Sales Lan
Viewing, & Saving Configurations • Viewing & Saving Configurations • running-config saved in DRAM • startup-config saved in NVRAM Router# copy run start Router# sh run Router# sh start Router# erase startup-config
Verifying Your Configuration • Tools to check your config (pp. 207-212): show running-config show startup-config ping an IP address show cdp nei detail to find out IP addresses trace to discover path through network telnet to devices with IP addresses sh interface to see one interface sh int e0 sh int s1 (line up/down protocol up/down) sh controllers s 0 (notice the space)
Hands-On Lab 4.5 Pages 197-198