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  • 1. Configuring and testing CCNA Exploration Semester 1 – Chapter 11
  • 2. Topics
    • 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
  • 3. Internetwork Operating System
    • 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.
  • 4. Access to the interface
    • Console port via serial connection
      • 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.
  • 5. Telnet, SSH, Aux
    • 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
  • 6. Configuration files
    • 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.
  • 7. Router storage areas
    • ROM
    • Permanent
    • Holds POST, boot instructions, basic IOS
    • Flash
    • Keeps contents
    • Holds IOS image
    • NVRAM
    • Keeps contents
    • Holds startup configuration file
    • RAM
    • Volatile
    • Holds runnning config, tables, queues etc
  • 8. Router IOS modes User EXEC mode Privileged EXEC mode enable disable + password Global Configuration mode Configure terminal Exit or Ctrl+z Specific Configuration modes Exit End Various commands
  • 9. Router prompts User EXEC mode Privileged EXEC mode Global Configuration mode Specific Configuration modes Router> Router# Router(config)# Router(config-if)# and others
  • 10. EXEC modes
    • 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
  • 11. Configuration modes
    • 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.
  • 12. Leaving configuration modes
    • 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#
  • 13. Command Structure Followed by <Enter>
  • 14. ? To get help
    • ? 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.
  • 15. Shortened commands
    • 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’
  • 16. Other error messages
    • 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
    ^ ^
  • 17. Keyboard shortcuts
    • 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
  • 18. Show commands
    • 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.
  • 19. General show commands
    • 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.
  • 20. Show interfaces
    • 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
  • 21. Save configuration
    • 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.
  • 22. Hostname
    • 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.
  • 23. Console password
    • 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
  • 24. Vty password for Telnet
    • 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
  • 25. Enable and enable secret
    • 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.
  • 26. Message of the day
    • 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.
  • 27. Reload
    • 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.
  • 28. Back up to TFTP server
    • Start TFTP server software on host
    • Paris# copy running-config tftp
    • Remote host []?
    • Name of configuration file to write [Paris-config]? Paris12Oct07
    • Write file Paris12Oct07 to [confirm] y
    • Writing Paris12Oct07 ! ! ! ! ! ! [OK]
  • 29. Back up as text file
    • Start text capture
    • Name file
    • show run
    • Stop text capture
    • Open saved file and
  • 30. TeraTerm text file
    • 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.
  • 31. Erase startup configuration
    • 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
  • 32. Restore file from TFTP server
    • 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.
  • 33. 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
  • 34. Configure a router interface
    • Paris(config)# interface FastEthernet 0/0
    • Paris(config-if)# ip address
    • 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
  • 35. Configure a router interface
    • Paris(config)# interface serial 0/0
    • Paris(config-if)# ip address
    • (Paris(config-if)# clock rate 64000 )
    • Paris(config-if)# no shutdown
    • Paris(config-if)# exit
    DCE only
  • 36. Description
    • 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
  • 37. Switch interfaces
    • 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.
  • 38. Switch IP address
    • The switch IP address goes on a virtual interface, not a real one, normally VLAN1.
    • SwA(config)# interface VLAN1
    • SwA(config-if)# ip address
    • SwA(config-if)# no shutdown
    • SwA(config-if)# exit
  • 39. Switch default gateway
    • SwA(config)# ip default gateway
    • 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.
  • 40. Interface – show commands
    • 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.
  • 41. Up or down
    • Interface status: Layer 1
      • Up
      • Down
      • Administratively down (no shutdown to bring up)
    • Protocol: Layer 2
      • Up
      • Down (no keepalive signal received)
  • 42. Ping – step by step
    • Ping (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
  • 43. Network baseline
    • Measure and record performance
      • 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
  • 44. Find out about nodes
    • 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
  • 45. Summary
    • Hierarchical Design model addresses performance, scalability, maintainability & manageability issues.
    • Traffic Analysis is used to monitor network performance.
    • Hierarchical Design Model is composed of 3 layers:
      • Access
      • Distribution
      • Core
    • Switches selected for each layer must meet the needs of each hierarchical layer as well as the needs of the business.
  • 46. Labs & Activities * If no previous Packet Tracer experience, else strongly recommended Mandatory 11..2.3 Lab Mandatory* 11.1.6 Lab Review carefully 11.2.2 Lab Mandatory 11.2.1 Lab Mandatory 11.1.7 Lab Detail Type
  • 47.