1. 1 © 2004, Cisco Systems, Inc. All rights reserved. CCNA 2 v3.1 Module 2 Introduction to Routers

2. 222 © 2004, Cisco Systems, Inc. All rights reserved. Objectives

3. 333 © 2004, Cisco Systems, Inc. All rights reserved. Cisco IOS Software It is the embedded software architecture in all of the Cisco routers and is also the operating system of the Catalyst switches Without an operating system, the hardware does not have any capabilities The Cisco IOS provides the following network services: Basic routing and switching functions Reliable and secure access to networked resources Network scalability

4. 444 © 2004, Cisco Systems, Inc. All rights reserved. Router User Interface Cisco IOS software uses a command-line interface (CLI) as its console environment to configure router The CLI is accessible through several methods: Console port: uses a low speed serial connection directly from a computer or terminal to the console connection on the router Auxiliary port: uses a dialup connection with a modem Telnet session: at least one interface must be configured with an IP address, and virtual terminal sessions must be configured for login and passwords.

5. 555 © 2004, Cisco Systems, Inc. All rights reserved. Router User Interface

6. 666 © 2004, Cisco Systems, Inc. All rights reserved. Router User Interface Mode The IOS provides a command interpreter service known as the command executive (EXEC) After each command is entered, the EXEC validates and executes the command. As a security feature the Cisco IOS software separates the EXEC sessions into two access levels These levels are user EXEC mode: allows only a limited number of basic monitoring commands and can be identified by the > prompt. privileged EXEC mode: allows to use all configuration and management command and can be identified by the # prompt

7. 777 © 2004, Cisco Systems, Inc. All rights reserved. Router User Interface Modes

8. 888 © 2004, Cisco Systems, Inc. All rights reserved. CISCO ISO Software Features Cisco continues to develop different IOS software images to optimize the Cisco IOS software Although there are numerous IOS images for different Cisco device models and feature sets, the basic configuration command structure is the same One of the main considerations when selecting a new IOS image is compatibility with the router flash and RAM memory

9. 999 © 2004, Cisco Systems, Inc. All rights reserved. The naming convention for the different Cisco IOS releases contains three parts: The platform on which the image runs The special features supported in the image Where the image runs and whether it has been zipped or compressed

10. 10 © 2004, Cisco Systems, Inc. All rights reserved. Cisco IOS Naming Conventions

11. 11 © 2004, Cisco Systems, Inc. All rights reserved. Cisco IOS Naming Conventions (Continued)

12. 12 © 2004, Cisco Systems, Inc. All rights reserved. Operating Cisco IOS Software

13. 13 © 2004, Cisco Systems, Inc. All rights reserved. Operation of Cisco IOS Software At startup, a Cisco router normally loads into RAM and executes one of these following operating environments modes: ROM monitor Boot ROM Cisco IOS

14. 14 © 2004, Cisco Systems, Inc. All rights reserved. ROM Monitor The ROM monitor performs the bootstrap process and provides low-level functionality and diagnostics It is used to recover from system failures and to recover a lost password The ROM monitor cannot be accessed through any of the network interfaces It can only be accessed by way of a direct, physical connection through the console port.

15. 15 © 2004, Cisco Systems, Inc. All rights reserved. Boot ROM Mode Only a limited subset of the Cisco IOS feature set is available It allows write operations to flash memory It is used primarily to replace the Cisco IOS image that is stored in flash A copy command is used to copy an IOS image that is stored on a TFTP server into the flash memory of a router

16. 16 © 2004, Cisco Systems, Inc. All rights reserved. Cisco IOS This is the normal operation of Cisco IOS that is stored in as an image in flash In some devices, the IOS is executed directly from flash However, most Cisco routers require a copy of the IOS to be loaded into RAM and also executed from RAM Some IOS images are stored in flash in a compressed format and have to be expanded when copied to RAM.

17. 17 © 2004, Cisco Systems, Inc. All rights reserved. Initial Startup of Cisco Routers The goal of the startup routines for Cisco IOS software is to start the router operations To do this, the startup routines must accomplish the following: Verify that the router hardware is tested and functional. This operation is known as power on self test (POST) Find and load the Cisco IOS software. Find and apply the startup configuration file or enter the setup mode.

18. 18 © 2004, Cisco Systems, Inc. All rights reserved. Steps in Router Initialization

19. 19 © 2004, Cisco Systems, Inc. All rights reserved. Setup Mode

20. 20 © 2004, Cisco Systems, Inc. All rights reserved. Router LED Indicators Cisco routers use LED indicators to provide status information. LED indicators will vary for different Cisco router models.

21. 21 © 2004, Cisco Systems, Inc. All rights reserved. The Initial Router Bootup

22. 22 © 2004, Cisco Systems, Inc. All rights reserved. Examining the Initial Boot up Output

23. 23 © 2004, Cisco Systems, Inc. All rights reserved. Examining the Initial Bootup Output continued

24. 24 © 2004, Cisco Systems, Inc. All rights reserved. Establish a Console Session All Cisco routers include an EIA/TIA-232 asynchronous serial console port. The console port is an RJ- 45. Use an RJ-45 to RJ45 rollover cable with a female RJ-45 to DB-9 adapter to connect a PC to the console port

25. 25 © 2004, Cisco Systems, Inc. All rights reserved. Router Modes

26. 26 © 2004, Cisco Systems, Inc. All rights reserved. User Mode Commands

27. 27 © 2004, Cisco Systems, Inc. All rights reserved. Privileged Mode Commands

28. 28 © 2004, Cisco Systems, Inc. All rights reserved. clock set Command

29. 29 © 2004, Cisco Systems, Inc. All rights reserved. Using IOS Command history

30. 30 © 2004, Cisco Systems, Inc. All rights reserved. The User Interface Error Indicator

31. 31 © 2004, Cisco Systems, Inc. All rights reserved. The show version Command

32. 32 © 2004, Cisco Systems, Inc. All rights reserved. Summary