Configuring and Testing Your Network
Network Fundamentals – Chapter 11
Sandra Coleman, CCNA, CCAI
Version 4.0
•
•
•
•
•
Define the role of the Internetwork Operating System
(IOS).
Use Cisco CLI commands to perform basic router and
switch configuration and verification.
Given a network addressing scheme, select, apply, and
verify appropriate addressing parameters to a host.
Use common utilities to verify network connectivity
between hosts.
Use common utilities to establish a relative performance
baseline for the network.
Objectives
Role of Internetwork Operating System (IOS)
Used for routers, LAN switches, Wireless access points, etc. Stored in
FLASH memory – easily upgraded – copied into RAM at startup.
• Provides – basic routing/switchig functions, reliable access, scalability
• Accessed via the command line (CLI)
Accessing the router
Console port – mgt.
port. Used to manage
if network services are
not available & for
initial configuration.
SSH is always a better
practice than telnet for
security reasons. –
uses encryption.
Role of Internetwork Operating System (IOS)
startup – used during boot time to configure the device.
Stored in NVRAM (non-volatile
Changes made
Stored in RAM –
here immediately
if changes aren’t
affect the
saved..they are
operation of the
lost with powerdevice! These
down.
changes can
then be SAVED
to the startup
Sometimes
configuration.
called the
backup
configuration
Role of Internetwork Operating System (IOS)
• Hierarchical structure of
modes for IOS: User,
Privilege, Global
Configuration, other
configuration modes
• Help is context-sensitive
for that mode
IOS Modes and their prompts
Limited capabilities
Set up a password for this mode!
Sometimes called Enable Mode
Can only be
reached from
Inside
privileged
mode!
Examples:
Basic Command Structure
Using Help
 Context-sensitive – list of commands for CURRENT mode
 Command syntax check – checks that the commands are spelled correctly and
arguments are recognizable
 Hot Keys & Shortcuts – makes configuring and troubleshooting easier!
Hot Keys and Shortcuts
• Ctrl-R - Redisplays a line
• Down Arrow - Allows user to scroll forward through former
commands
• Up Arrow - Allows user to scroll backward through former
commands
• Ctrl-Shift-6 - Allows the user to interrupt an IOS process such as
ping or traceroute
• You can also ABBREVIATE COMMANDS as long as the
abbreviation is UNIQUE enough the CLI knows what you mean.
Other hot keys to know
IOS Examination Commands
• You’ll become familiar with the ones you need to know
Show commands
• show version – shows info about versions and configuration register setting
• Show ip route – displays the routing table of the router…discuss in lab! – be
familiar with the output and how to interpret it.
• show arp - Displays the ARP table of the device.
• show mac-address-table - (switch only) Displays the MAC table of a switch.
• show startup-config - Displays the saved configuration located in NVRAM.
• show running-config - Displays the contents of the currently running
configuration file or the configuration for a specific interface, or map class
information.
• Show interfaces - shows lots of things, especially input/output errors
• show ip interfaces - Displays IPv4 statistics for all interfaces on a router.
• show ip interface brief. This is useful to get a quick summary of the interfaces
and their operational state.
Configuration Modes
• Identify several of the configuration modes, their purpose
and their associated prompt
Naming Devices
• Choosing and documenting names makes it easier to
remember, discuss, and identify network devices.
• Be consistent in naming conventions. Create a naming
convention when you create an addressing scheme.
Naming Devices – Know the command!
• Consider the location and purpose of the device when naming it.
• Notice, not only the command, but the mode you are in!
Passwords!
• Used to limit access to devices, strengthen security, etc.
• Console, enable secret, and vty passwords
passwords
• Service password-encryption – command that causes passwords to
appear encrypted so that others can’t see them when viewing
configuration files.
Know these
commands!
Must first do
‘enable
secret
mypassword’
Notice the
prompts!
Banners for security
• Simply warns the user they are entering unauthorized territory.
NEVER welcome anyone with a banner.
• Banner motd # message #
Managing configuration files
• Show start
• Edit if necessary
• Copy run start (abbreviated version) – to save to startup
• Copies files (running or startup configuration) to a FTP
server.
• To completely START over –
•Erase start (you will have to confirm this)
•Reload (does a soft boot of the router or switch)
•Should be completely empty
Managing configuration files
Saving files with Hyperterminal Capture
• I’ll show you how
to do this…
Configure the router interfaces
Router(config) interface fa0/1
Router(config-if) ip address 192.168.20.1 255.255.255.0
Router(config-if) no shutdown
Serial interface
• You configure these the same way, you just have to make sure
you put the clock rate command on the DCE end of the line.
• Router(config-if) clock rate 56000
• ALWAYS make sure you do a NO SHUTDOWN on every
interface.
• There are some troubleshooting problems on the test that give
you the commands and the topology and ask you what is
wrong…pay attention to IP addresses, clock rate settings, etc.
• Not having a clock rate set will PROHIBIT communication
altogether…one of the most common mistakes by new users.
Ethernet interfaces
• Different routers have different interface names,
depends on the model. E0, e0/0, fa0/0 can all mean
the same thing.
Interface descriptions – not required
Switch configuration
Ip default-gateway –
like any other device, a
switch needs a gateway
defined to get outside
of the local network and
to allow remote access
from users outside the
remote network!
Testing the TCP/IP stack
• Tests layers 1-3 of the
OSI model. Uses
ICMP protocol the
check for connectivity
• ! – successful, . –
timed out, U – ICMP
unreachable message
recv’d
Testing the interfaces
• Discuss these steps in
troubleshooting. They
will show layer 1
and/or layer 2 errors
looking at sh ip int br
output – KNOW what
this tells you!
Troubleshooting switches
• Switch
example
Testing remote connectivity
• Use the ping command and check a router’s routing table for next
hop availability.
• Always ping your GATEWAY first to make sure that connections is
active.
Pinging your own IP address
• Use the ping
command to
determine if the
IP protocol is
properly bound
to an NIC
Communicating remotely
• Use the ping
command to verify
that the local host
can communicate
across the
internetwork to a
given remote host.
Troubleshooting link failures
• Ping – from your PC to each nearest router link (ethernet, serial
on your gateway, serial on next hop, etc.) You can easily find
the point of failure.
Traceroute to find failures
• Use trace commands to identify network connectivity problem
Use Common Utilities to Establish a Relative Performance
Baseline for the Network
• Use the output of the
ping command, saved
into logs, and
repeated over time, to
establish relative
network performance
• Use the output of the
traceroute command,
saved into logs, and
repeated over time,
to establish relative
network
performance
Use Common Utilities to Establish a Relative
Performance Baseline for the Network
Use Common Utilities to Establish a Relative Performance
Baseline for the Network
• Trace the steps for
verifying the physical
addresses of the hosts
Labs –11-2, pg. 310
11-5, pg. 342
Chapter 11 – FINISHED!
Online Test – TBA – For a homework grade
Test - TBD
Don’t forget to sign the HANDS-ON sign-up sheet NEXT WEEK!
(Posted by my office)
NO HOMEWORK – I’m giving you a break. Come work in the lab
anytime you can to work on the actual equipment.
There are LOTS of packet tracer activities in the textbook that will let
you practice these commands…I encourage you to spend some time
during Thanksgiving Holidays to work on this. You will have to KNOW
these commands by heart…no books, no notes…you can only use
the online help facility.