Sybex CCNA 640-802
Chapter 4: Cisco’s IOS and SDM
Chapter 4 Objectives
• The Cisco router IOS
• Enhanced editing
• Administrative functions
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Hostnames
Banners
Passwords
Interface descriptions
• Verifying your configuration
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Cisco Router IOS
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Carries network protocols and functions
Connects high-speed traffic between devices
Adds security to control access
Provides scalability for growth
Supplies reliability
– You should understand that routers are seldom
directly connected to user devices, such as
workstations, printers, etc. Normally, a router is
connected to another router, or it is connected to a
switch (or a hub in an older environment) which is in
turn connected to workstations or other devices
found in an office.
p. 173
Router Access (Connecting to a Cisco Router - 173)
• Console port (console)
– Rollover cable (each end is a mirror-image o/t other)
• RJ-45 to DB-9
• RJ-45 to DB-25
• Auxiliary port (AUX)
– Can function like a console port
– Or, can accept modem commands, i.e., from
sources outside the network (i.e., “out of band”)
• Virtual terminal (VTY)
– This is for telnet access
– This kind of access is from within the network (i.e.,
“in band”.
Connecting To A Cisco Router
Cisco 2811
Cisco 1841
Cisco ISR Routers
• Distinguish older Cisco routers from the newer,
ISR routers
• The “Integrated Services Routers” line runs a
“hardened” version of Linux and is generally
deployed at branch offices.
• ISR routers are part of a trend to include more
services in routers – probably making them
more profitable.
Connecting To A Cisco Router
Connecting Via Terminal Programs
• Establish a connection
– Physical connection through console
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9600 bits per second
data bits 8
stop bits 1
parity “none”
flow control “none”
– Logical connection through VTY
– Terminal programs
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HyperTerminal,
Microphone Pro,
ProComm Plus,
Telix,
Tera Term
Bringing up a Router
- pg 175
• Boot-up process:
1: POST
2: Looks for the Cisco IOS from Flash memory
3: IOS loads & looks for a valid configuration;
• startup-config
• stored in nonvolatile RAM (NVRAM)
• i.e., the IOS is stored in a compressed state in nonvolatile memory, or NVRAM
• When the router boots it is “decompressed” into RAM.
4: If a valid config is not found in NVRAM:
• setup mode
p. 177
Bringing up a Router
- pg 175-76
• After the POST, some hardware information is
listed. Specifically, memory information:
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Copyright (c) 1998-2003 by Boson Software
C2500 platform with 20480 Kbytes of main memory [RAM]
program load complete, entry point:0x8000080000, size:0x43b7fc
Self decompressing the image :
########################################
########################################
########################################
########################################
########################################
################# [OK]
Cisco Internetwork Operating System Software
IOS ™ C2500 Software (C2500-IK937S2-M), Version 12.3(20) Release software fc2 [IOS version]
IOS (tm) 2500 Software(C2500-enterprise), Version 5.0, RELEASE SOFTWARE
Copyright (c) 1998-2003 by Cisco Systems, Inc.
-- some output omitted -Boson 2500 (BOSS) emulator (revision 5.0) with 20480K/512K simulated memory.
BOSS, Version 5.0
1 Ethernet/IEEE 802.3 interface(s)
3 ISDN Basic Rate interface(s)7K bytes of simulated non-volatile configuration memory.
8192K bytes of simulated processor flash (Read/Write)
Bringing up a Router
• Boot-up process:
Setup Mode
• Basic Management Setup
• Extended Setup
• Command-Line Interface
Command-Line Interface (CLI)
• More flexible than setup mode.
• To use the CLI, just say “No” to entering the
initial configuration dialog.
• Initial prompt consists of two parts
– Hostname
– Greater than symbol (>)
p. 179
Logging into the Router
• User mode:
– Router>
– Used mostly to view statistics
• Privileged mode:
– Router#
– Used to view & change router configuration
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 append the current runningconfig
p. 1
Configuration Modes
• Global configuration mode
– Router(config)#
• Interface mode
– Router(config–if)#
• Line configuration mode
– Router(config-line)#
• Router configuration mode
– Router(config-router)#
Configuration Modes
Configuration
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CLI Prompts
Interfaces
Sub-interfaces
Line Commands
Routing Protocol
Configurations
Editing &
Help
Features
Editing & Help Features
• Commands starting with a certain letter
Router#c?
clear clock configure connect copy
• Enhanced Editing Commands
• Router-Command History
• Gathering Basic Routing Information
– show version
Enhanced Editing Commands
Enhanced Editing Commands (cont.)
Router Command History
Gathering Basic
Routing
Information
Administrative Functions
The administrative functions that you can
configure on a router and switch are
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Hostnames
Banners
Passwords
Interface descriptions
Hostnames & Descriptions
• Hostnames
Router(config)#hostname todd
todd(config)#
• Descriptions
Atlanta(config)#int e0
Atlanta(config-if)#description Sales Lan
Banners
• Purpose: welcome message
• Types
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exec:
incoming:
login:
motd:
set EXEC process creation banner
set incoming terminal line banner
login banner
set “Message of the Day” banner
• Delimiting character
Banners
Setting the Passwords
• 5 passwords:
– 1st two used to set your enable password
• Used to secure privileged mode;
• Router>enable
• Or Router>en (because no other commands at privileged level
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begin with “en”
– 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
Note: the secret password supersedes the enable
password, i.e., if you set both passwords, you will be
asked for the secret password.
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Auxiliary Password
Console Password
Telnet Password
Encrypting Your Password
Router(config)#service password-encryption
Passwords
Passwords
Passwords
Passwords
Passwords
Interface Descriptions
Setting descriptions on an interface is helpful to the administrator and, like
the hostname, only locally significant. The description command is a
helpful one because you can, for instance, use it to keep track of circuit
numbers.
Here’s an example:
Atlanta(config)#int e0
Atlanta(config-if)#description Sales Lan
Atlanta(config-if)#int s0
Atlanta(config-if)#desc Wan to Miami circuit:6fdda4321
You can view the description of an interface either with the
show running-config command or the show interface
command.
Router Interfaces
• Bringing up an Interface
no shutdown
shutdown
show interface
• 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 Interface Commands
clock rate
& bandwidth
(entered in kilobits)
Configuring The Time And Date
Viewing, & Saving Configurations
• Viewing & Saving Configurations
– running-config saved in
– startup-config saved in
copy run start
sh run
sh start
erase startup-config
DRAM
NVRAM
Verifying Your Configuration
Tools:
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show running-config
show startup-config
ping
show cdp nei detail
trace
telnet
Other Verification Methods
• Verifying with the show interface command
– Router#show interface ?
• Verifying with the show ip interface command
(layer 3 info)
– Router#show ip interface
– Router#show ip interface brief
– Router#show controllers
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Router# show run
Version 12.1
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
hostname Router
ip subnet-zero
!
interface Serial0
ip address 172.16.12.1 255.255.0.0
no ip directed-broadcast
clock rate 56000
!
interface Serial1
no ip address
no ip directed-broadcast
shutdown
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interface Ethernet0
ip address 192.168.1.1 255.255.255.0
no ip directed-broadcast
!
interface Ethernet1
no ip address
no ip directed-broadcast
shutdown
Show Run command
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interface Bri0
no ip address
no ip directed-broadcast
shutdown
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router igrp 1
network 192.168.1.0
network 172.16.0.0
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ip classless
no ip http server
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line con 0
transport input none
line aux 0
line vty 0 4
!
no scheduler allocate
end
Router Components
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ROM
Flash memory
NVRAM
RAM/DRAM
Router Components
• ROM
– Read-only memory (ROM)
– Bootstrap program
– ROM monitor firmware
– ROM monitor mode
• (>) or (rommon 1>)
Router Components
• Flash memory
– Erasable, programmable, read-only memory
(EPROM)
– Contains the Cisco IOS
– Can store multiple IOS
– “show version” command (sh ver)
– “show flash” command
(sh fla)
Router Components
• NVRAM
– Nonvolatile random access memory (NVRAM)
– Special type of RAM
– Not cleared when router is rebooted
– Startup configuration file
– “show start” command (sh sta)
Router Components
• Random access memory (RAM)
– Volatile
– Information is not retained during router reboot
– Running configuration
– “show running-config” command (sh ru)
– “show memory” command
(sh me)
– “show buffers” command
(sh buf)
Summary
• Go through all the written labs and review questions
• Review answers in class
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