Transcript Ethernet - wmmhicks.com

Configuring and
testing
CCNA Exploration Semester 1
Chapter 11
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Topics
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The Internetwork Operating System (IOS).
Devices that have the IOS embedded.
IOS commands available to a device.
IOS modes of operation.
Basic IOS commands.
Basic show commands.
Configuration files
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Internetwork Operating System
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Most Cisco devices use the Cisco IOS.
Details vary with the device and feature set.
Normal access through a command line.
Stored in flash memory and can be
upgraded.
Usually copied into RAM when the device is
powered on, and run from RAM.
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Access to the interface
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Console port via serial connection
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Initial configuration
Disaster recovery
When network access has failed
Password recovery
As well as general management
Console access does not require a password.
Configure a password. Lock the door.
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Telnet, SSH, Aux
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Later management can be via Telnet
There must be an IP address on the port
A password must be configured
Secure shell gives better security
AUX port can be used locally or via modem
but by default does not show error messages
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Configuration files
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Hold the commands that have been
configured on the router to customise it.
Running configuration in RAM holds
commands that are in current use
Startup configuration in NVRAM holds saved
commands. These are kept when the power
is off and usually copied back into RAM when
the router is re-started.
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Router storage areas
ROM
Permanent
Holds POST, boot
instructions, basic IOS
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NVRAM
Keeps contents
Holds startup
configuration file
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Flash
Keeps contents
Holds IOS image
RAM
Volatile
Holds runnning config,
tables, queues etc
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Router IOS modes
User EXEC mode
enable
disable
+ password
Privileged EXEC mode
Configure terminal
Exit or Ctrl+z
Global Configuration mode
Various commands
Exit
End
Specific Configuration modes
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Router prompts
User EXEC mode
Router>
Privileged EXEC mode
Router#
Global Configuration mode
Specific Configuration modes
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Router(config)#
Router(config-if)#
and others
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EXEC modes
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You log in to User EXEC mode
Router>
You can give basic monitoring commands but
cannot change the configuration
Enter enable to go to Privileged EXEC mode
Router#
Password may be used for security
You can give more commands and can go to
configuration modes
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Configuration modes
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Start in privileged EXEC mode and enter the
configure terminal (config t) command
Router# config t
Router(config)#
The prompt changes
This is global configuration mode
Additional commands take you to interface
configuration, router configuration etc.
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Leaving configuration modes
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From interface configuration mode there are
several ways of getting to privileged EXEC
Router(config-if)# exit
Router(config)# exit
Router#
Router(config-if)# end
Router#
Router(config-if)# Ctrl+z
Router#
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Command Structure
Followed by <Enter>
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? To get help
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? Gives a list of commands available from
the current prompt.
Command followed by space then ? Gives a
list of keywords or arguments that can be
used.
Start of command followed by ? with no
space shows how the word can be continued.
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Shortened commands
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Router#show running-config
Router#show run
Router#sh ru
It needs enough letters of each word to be
unambiguous. (Tab key shows whole word)
Router#s ru
% Ambiguous command: ‘s’
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Other error messages
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Switch#clock set
% Incomplete command
Switch#clock set 19:50:00 25 6
^
% Invalid input detected at ‘^’ marker
Router#show runming-config
^
% Invalid input detected at ‘^’ marker
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Keyboard shortcuts
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Tab
completes a partial command
Backspace erases to left of cursor
Ctrl+D erases at cursor (Delete does not)
Ctrl+Z returns from any config mode to
privileged exec mode
Ctrl+C leave Setup mode
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At the ---More--- prompt
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Enter shows the next line
Spacebar shows the next screenful
Needed with commands such as
show running-config that produce more
than one screen of text.
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Show commands
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Show ? To get a list
Many different show commands to give
information about every aspect of the router
and its operation
We use some of the most common.
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General show commands
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Show running-config shows the
configuration file from RAM
Show startup-config shows the saved
configuration file from NVRAM
Show version gives information about the
IOS and the router itself. It shows the
configuration register, which controls how the
router starts up.
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Show interfaces
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Gives statistics for all interfaces
In particular, says if the interface is up and if
the protocol is up – important in
troubleshooting.
Show interfaces serial 0/0 to show one
selected interface
You can shorten to show int s 0/0
Show ip interfaces gives IP statistics
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Save configuration
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Router#copy running-config startup-config
Router#copy run start (shortened)
Router#wr (Old fashioned, short for write, but
it works and is safe.)
Beware! A typing error in the copy command
can delete the operating system. If you get an
odd message about Flash – hands off – call for
help.
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Hostname
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Router>enable
Router#config t
Router(config)#hostname Paris
Paris(config)#
Configure a suitable hostname so that you
know which router you are managing and so
that you can identify it in network
documentation.
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Console password
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Paris(config)#line con 0
Paris(config-line)#password cisco
Paris(config-line)#login
Paris(config-line)#exit
Restricts access via the console
Use cisco as the password in labs.
Use a proper strong password on production
networks
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Vty password for Telnet
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Paris(config)#line vty 0 4
Paris(config-line)#password cisco
Paris(config-line)#login
Paris(config-line)#exit
Allows and restricts access via 5 vty lines
Use cisco as the password in labs.
Use a proper strong, different password on
production networks
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Enable and enable secret
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Paris(config)#enable secret class
The password class is needed when you
type enable to enter privileged exec mode
This password is encrypted
Paris(config)#enable password cisco
Not encrypted, used on older routers
If you configure both, then only the enable
secret is used.
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Message of the day
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Paris(config)#banner motd # No
unauthorised access #
# is a delimiter to show where the message
starts and ends.
Any character can be used as long as it does
not appear in the message.
The message should make it clear that
unauthorised access is forbidden.
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Reload
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Shuts down the router and then starts it
again.
If the configuration has changed then you are
prompted to save it.
The running configuration in RAM is lost.
The startup configuration from NVRAM is
(usually) loaded into RAM on startup.
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Back up to TFTP server
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Start TFTP server software on host
Paris#copy running-config tftp
Remote host []? 172.16.1.1
Name of configuration file to write [Parisconfig]? Paris12Oct07
Write file Paris12Oct07 to 172.16.1.1?
[confirm] y
Writing Paris12Oct07 ! ! ! ! ! ! [OK]
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Back up as text file
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Start text capture
Name file
show run
Stop text capture
Open saved file and “tidy up”.
Remove unwanted symbols at –More--No shutdown command on interfaces
Passwords in plain text (ouch!)
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TeraTerm text file
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TeraTerm is an open source Telnet client.
It can also act as a SSH client
It can capture text and save it as a file.
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Erase startup configuration
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Paris#erase NVRAM:startup-config
Paris#erase startup-config
Paris#erase start
If you reload, then the router starts up with
the default configuration. No passwords, no
IP addresses etc.
Caution if you get this command wrong then
you could erase something else, e.g. IOS
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Restore file from TFTP server
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Router#copy tftp running-config
You will be prompted for IP address and file
name.
Configuration is copied into RAM and takes
effect at once.
Save to NVRAM.
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Restore text file
Go to global configuration
mode
 Hyperterminal Transfer
menu
 Send text file…
Or
 Copy text from text file
 “Paste to host” into Hyperterminal session
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Configure a router interface
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Paris(config)#interface FastEthernet 0/0
Paris(config-if)#ip address 172.16.1.1
255.255.0.0
Paris(config-if)#no shutdown
Paris(config-if)#exit
Interface names vary, depending on whether
the router is modular and on the bandwidth.
E.g. interface Ethernet 0 on an older router
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Configure a router interface
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Paris(config)#interface serial 0/0
Paris(config-if)#ip address 192.168.4.1
255.255.255.0
(Paris(config-if)#clock rate 64000)
Paris(config-if)#no shutdown
DCE only
Paris(config-if)#exit
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Description
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Paris(config)#interface fa0/0
Paris(config-if)#description Connects to
Paris central switch
Can include circuit and contact information
Not needed for the operation of the router
Valuable for documentation as it is included
in the configuration listing
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Switch interfaces
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Switch physical interfaces do not have IP
addresses
They are active by default and do not need
the no shutdown command.
It can be useful to give them a description.
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Switch IP address
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The switch IP address goes on a virtual
interface, not a real one, normally VLAN1.
SwA(config)#interface VLAN1
SwA(config-if)#ip address 172.16.255.1
255.255.0.0
SwA(config-if)#no shutdown
SwA(config-if)#exit
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Switch default gateway
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SwA(config)#ip default gateway
172.16.255.254
Just like a workstation, a switch needs a
default gateway if it exchanges messages
with devices on a different network.
The default gateway is the address of the
local router.
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Interface – show commands
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show interfaces states whether up or down,
gives some protocol information and statistics
about interface use.
show ip interface gives IP addresses and
much more.
show ip interface brief gives summary of IP
addresses and whether up/down. Very useful
command.
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Up or down
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Interface status: Layer 1
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Up
Down
Administratively down (no shutdown to bring up)
Protocol: Layer 2
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Up
Down (no keepalive signal received)
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Ping – step by step
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Ping 127.0.0.1 (loopback, is TCP/IP OK?)
Ping own IP address (are NIC hardware and
software all right? Is IP address bound?)
Ping local hosts (checks own configuration
and that of others)
Ping gateway
Ping other intermediate routers
Ping hosts on remote networks
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Network baseline
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Measure and record performance
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At different times
Under different conditions
Repeatedly over a period of time
Build up a record of network performance
Useful in troubleshooting and optimising the
network
Helps predict future problems
Helps planning for change
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Find out about nodes
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Ping – used from workstation, router or
switch – shows if destination can be reached
Traceroute – shows hops along the path
Arp -a on workstation – shows list of MAC
and IP addresses
show mac-address-table on switch – shows
list of MAC addresses and switch ports
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The End
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