Introduction to the Cisco IOS 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

2501 Router

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: Router then displays your settings 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

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 Auxiliary password Console password 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 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