1. Real-Life Hardware: Cisco q Introduction to Cisco IOS

2. What is IOS? q Internetwork Operating System q A derivative of BSD UNIX q Custom built by Cisco for each platform q Pre-packaged and static. q Features available in different revisions (for a price!) q GUI’s available, but 90%+ of users still prefer command-line configuration.

3. IOS and Hardware q IOS is designed to be hardware independent. q A high end router may use ASIC’s q A smaller access router may use the central processor. q Configuration and monitoring commands should be almost identical!

4. Router Components RAM RAM Stores configuration files Contents lost on power-off Large enough to hold large routing tables Stores Routing tables (remember: usually built dynamically) ARP cache (again, built dynamically and ephemeral) Fast-switching cache Packet buffers Packet hold queues

5. Router Components NVRAM NVRAM Non-volatile RAM Slow Content is NOT LOST on power off. Usually less than 100 Kbytes Stores Exclusively used to store configuration scripts that are parsed on power-up.

6. Router Components FLASH FLASH EEPROM (Electronically Erasable Programmable Read-Only Memory) Retained on power-down. May be off-board in the form of flashcards. Stores IOS versions. Allows for upgrading Operating System without replacing chip. Multiple versions of IOS may be stored at once (GREAT for testing of a new version!) Off-board configuration allows you to “put OS in your pocket”.

7. Router Components ROM ROM Read-Only Memory. Generally installed in factory and never touched again! Stores POST (power-on self test) Bootstrap program that calls IOS. Bare-bones version of an IOS. If IOS load routine fails, it defaults back to this version, giving limited functionality.

8. ROM init CONFIG SCRIPTNVRAM FLASHRAM Contains location of IOS, could be FLASH, TFTP, etc. TFTP? IOS Version Config Params from script.. Loaded IOS.. Route tables.. ARP.. Built during runtime

9. IOS Interface q IOS commands are very “assembly-like”. They are extremely granular, and often counter-intuitive. q This is somewhat alleviated with inline help. The “?” character will become your best friend. q Since these configurations are stored as text scripts, you can look up lots of examples on Cisco’s website.

10. In-line Help q Typing the “?” character either after a command or at some point during a word brings up configuration parameters: For instance, typing: “ac?” Will ask the IOS what commands begin with “ac”, it will respond with: “access-enable access-template” This also works to find command modifiers or subsets: “show ip ?” Asks the IOS what is available for the “show ip” command: “interface route …”

11. Shortcuts q Just like most *NIX’s, IOS has a wide array of shortcut keys to expedite configuration. q The most useful is the TAB key, which as you may know, completes a word.

12. Why connect to a router Until routers are configured they generally have no connection to any medium. By default most interfaces are turned off. To perform the initial install, a serial connection is set up to the console port.

13. Lab Goals q What will we learn in this lab? q A brief overview of the Cisco design philosophy. q How one can access a Cisco router. q The Cisco security model. q Command line usage and hints. q How to build a configuration script and store it in NVRAM. q What the CLI looks like and how it interacts. q What it feels like to get your hands on some real hardware!

14. Chapter 4 Objectives The Cisco router IOS Enhanced editing Administrative functions – Hostnames – Banners – Passwords – Interface descriptions Verifying your configuration 14

15. Cisco Router IOS Carries network protocols and functions Connects high-speed traffic between devices Adds security to control access Provides scalability for growth Supplies reliability

16. Router Access Console port (console) – Rollover cable, RJ-45 to DB-9, RJ-45 to DB-25 Auxiliary port (AUX) Virtual terminal (VTY)

17. Connecting To A Cisco Router Cisco 2811 Cisco 1841

18. Connecting To A Cisco Router

19. Connecting Via Terminal Programs Establish a connection – Physical connection through console 9600 bits per second, data bits 8, stop bits 1, parity “none”, flow control “none” – Logical connection through VTY Terminal programs HyperTerminal, Microphone Pro, ProComm Plus, Telix, Tera Term

20. Bringing up a Router Boot-up process: 1: POST 2: Looks for the Cisco IOS from Flash memory 3: IOS loads & looks for a valid configuration; startup-configuration startup-configuration stored in nonvolatile RAM (NVRAM) 4: If a valid configuration is not found in NVRAM: setup mode setup mode

21. Bringing up a Router Boot-up process:

22. Setup Mode Basic Management Setup Extended Setup Command-Line Interface

23. 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 (>)

24. Logging into the Router User mode: – Router> – Used mostly to view statistics Privileged mode: – Router# – Used to view & change router configuration

25. Overview of Router Modes Global changes: – config terminal or config t running-config – Changes made to running-config (DRAM) startup-config – To change the startup-config (NVRAM) config memory or config mem running-config Note: Any configuration changes need to be placed into RAM. Typing config mem or config net (from a TFTP host) will append the current running-config

26. Configuration Modes Global configuration mode – Router(config) Interface mode – Router(config–if)# Line configuration mode – Router(config-line)# Router configuration mode – Router(config-router)#

27. Configuration Modes

28. Configuration CLI Prompts Interfaces Sub-interfaces Line Commands Routing Protocol Configurations

29. Editing & Help Features

30. 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

31. Enhanced Editing Commands

32. Enhanced Editing Commands (cont.)

33. Router Command History

34. Gathering Basic Routing Information

35. Administrative Functions The administrative functions that you can configure on a router and switch are Hostnames Banners Password Interface descriptions

36. Hostnames & Descriptions Hostnames Router(config)#hostname SUST SUST(config)# Descriptions CSIT(config)#int e0 CSIT(config-if)#description CS LAN

37. Banners Purpose: welcome message Types – exec: set EXEC process creation banner – incoming: set incoming terminal line banner – login: login banner – motd: set message of the Day banner Delimiting character

38. Banners

39. Setting the Passwords 5 passwords: – 1st two used to set your enable password Used to secure privileged mode; Router>enable user – Other three are used to configure a password in user mode via: console port auxiliary port Telnet

40. Passwords Enable passwords Router(config)#enable password cisco Router(config)#enable secret cisco Auxiliary Password Console Password Telnet Password Encrypting Your Password Router(config)#service password-encryption

41. Passwords

46. 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: Khartoum(config)#int e0 Khartoum(config-if)#description CSIT LAN Khartoum(config-if)#int s0 Khartoum(config-if)#desc WAN to Dongola circuit:6fdda4321 You can view the description of an interface either with the show running-config command or the show interface command.

47. 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)

48. Configuring The Time And Date

49. Viewing, & Saving Configurations Viewing & Saving Configurations – running-config – running-config saved in DRAM – startup-config – startup-config saved in NVRAM copy run start sh run sh start erase startup-config

50. Verifying Your Configuration Tools: – show running-config – show startup-config – ping – show cdp nei detail – trace – telnet

51. 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

52. Router Components ROM Flash memory NVRAM RAM/DRAM

53. Router Components ROM – Read-only memory (ROM) – Bootstrap program – ROM monitor firmware – ROM monitor mode (>) or (rommon 1>)

54. Router Components Flash memory – Erasable, programmable, read-only memory (EPROM) – Contains the Cisco IOS – Can store multiple IOS – “show version” command – “show flash” command

55. Router Components NVRAM – Nonvolatile random access memory (NVRAM) – Special type of RAM – Not cleared when router is rebooted – Startup configuration file – “show start” command

56. Router Components Random access memory (RAM) – Volatile – Information is not retain during router reboot – Running configuration – “show running-config” command – “show memory” command – “show buffers” command

57. Summary Go through all the written labs and review questions Review answers in class

58. Lab References q Useful References: q http://www.cisco.com/ http://www.cisco.com/ q http://www.cisco.com/en/US/products/sw/iosswrel/ ps1824/products_command_references_books_lis t.html http://www.cisco.com/en/US/products/sw/iosswrel/ ps1824/products_command_references_books_lis t.html q http://www.cisco.com/en/US/products/sw/iosswrel/ ps1824/products_configuration_guides_books_list. html http://www.cisco.com/en/US/products/sw/iosswrel/ ps1824/products_configuration_guides_books_list. html