1. Router Components & Configuration
Purpose: This chapter reviews general networking theory and introduces students to some of Cisco’s product line.
Timing: This chapter takes approximately 1.5 hours to present.
Note: This section has a product selection tool laboratory exercise at the end.
Contents:
Objectives—This section explains what the student will be able to do at the end of this chapter.
Defining Network Components—This section displays where devices are placed in the network.
Mapping Business Needs to a Hierarchical Model—This section describes the heirarchical model used in network design.
OSI Model Overview—This section reviews the OSI model.
Communicating Between Layers—This section describes encapsulation and de-encapsulation.
Written Exercise 1—This section has a written exercise to test the students’ knowledge of the OSI model.
Physical Layer Functions—This section describes the physical layer of the OSI Model.
Data Link Layer Functions—This section describes the data link layer of the OSI Model.
Network Layer Functions—This section describes the network layer of the OSI Model.
Transport Layer Functions—This section describes the transport layer of the OSI Model.

2. Router Components & Configurations Topics
Physical components
Memory components
Configuration modes
Keystroke shortcuts
Configuring router name, passwords and interfaces
Router boot sequence
Managing the router IOS and configuration

3. Router Components
Ports
Interfaces
Memory

4. Router Ports Console port Aux port –
Where you connect from your computer to directly configure the router or switch.
Use rollover cable & DB9 connector
Aux port –
for modem access

5. Setting up a Console Connection
Device with console
PCs require an RJ-45 to DB-9 or RJ-45 to DB-25 adapter
COM port settings are 9600 bps, 8 data bits, no parity, 1 stop bit, no flow control
This provides out-of-band console access
AUX switch port may be used for modem-connected console
Emphasize:
Rollover cables are not the same as crossover cables. The pinouts for a rollover cable are 1-8, 2-7, 3-6, 4-5, 5-4, 6-3, and so on.
Students must also set up a HyperTerminal console session if they are on a Microsoft Windows ‘95 platform. The instructions to establish a console session using HyperTerminal are in the HyperTerminal appendix.

6. Router Interfaces Ethernet Serial Ethernet is 10 mbps
Fast Ethernet is 100 mbps (unless auto senses 10 mbps)
Serial
Speed determined by clocking across link
Uses various cables and connectors.

7. Router Memory Components
NVRAM
RAM
Config register
Slide 1 of 1
Purpose:
Emphasize:
Note:
RAM - Packet buffers, running configurations, running IOS
ROM - POST, Rom Monitor, Baby IOS (Rxboot)
NVRAM - Backup configurations, Config register
Flash - IOS
Flash memory is non-volatile. It behaves like a file system. It is more expensive than NVRAM. It is readable and writeable. The 2500 routers run from flash. If it is running IOS from flash, then the flash is in the readable state. Use the boot system command to boot an IOS from a tftp server so the 2500 can run from RAM if you need to write or erase flash online.
Flash
ROM

8. Random Access Memory (RAM)
Stores operating system during operation
Stores running configuration
Buffers for packets
Routing table
Other tables as needed

9. Non-volatile RAM (NVRAM)
Stores startup configuration
Battery backed-up

10. Flash Holds IOS permanently On switches also holds VLAN database
Can be used as a file system

11. Read-Only Memory (ROM)
POST
Bootstrap
Baby IOS
ROMMON (ROM monitor)

12. Router Power on and Bootup Sequence
Power on self test (POST)
Load and run bootstrap code
Find the IOS software
Load the IOS software
Find the configuration
Load the configuration
Run
Slide 1 of 1
Purpose:
Emphasize: In a later slide, there is a very detailed flowchart of the router startup process.

13. Finding the IOS Order of search: 1. Check configuration register
show
startup-config
NVRAM
Config register
show
version
Console
Flash
Order of search:
1. Check configuration register
2. Parse config in NVRAM
3. Default to first file in Flash
4. Attempt net boot
5. RXBOOT
6. ROMMON
IOS
Slide 1 of 1
Purpose:
Emphasize:
Note: There is a detail flowchart of the router startup process on the next slide.

14. Determining the Current Configuration Register Value
wg_ro_a#show version
Cisco Internetwork Operating System Software
IOS (tm) 2500 Software (C2500-JS-L), Version 12.0(3), RELEASE SOFTWARE (fc1)
Copyright (c) by cisco Systems, Inc.
Compiled Mon 08-Feb-99 18:18 by phanguye
Image text-base: 0x03050C84, data-base: 0x
ROM: System Bootstrap, Version 11.0(10c), SOFTWARE
BOOTFLASH: 3000 Bootstrap Software (IGS-BOOT-R), Version 11.0(10c), RELEASE SOFTWARE (fc1)
wg_ro_a uptime is 20 minutes
System restarted by reload
System image file is "flash:c2500-js-l_120-3.bin"
--More--
Configuration register is 0x2102
Slide 1 of 1
Purpose:
Emphasize: Use the show version command to display the value of the Config register setting. When you change the config register, we will see from the show version output:
Configuration register is 0x2102 (will be 0x2142 at next reload).
The new config register value will be used at the next reload.
Configuration register value in show version

15. Configuration Register Values
Router#configure terminal
Router(config)#config-register 0x2102
[Ctrl-Z]
Router#reload
Configuration register bits 3, 2, 1, and 0 set boot option
Slide 1 of 4
Purpose: This slide shows how to use the config-register command to set the boot field. Emphasize: Layer 1—Shows the example of the config-register command. It assumes the network administrator will set the register to the default setting of 0x2102. (0x means the number is in hex).
In this course, limit the focus to the boot field that is formed by bits 3, 2, 1 and 0.

16. Configuration Register Values
Router#configure terminal
Router(config)#config-register 0x2102
[Ctrl-Z]
Router#reload
Configuration register bits 3, 2, 1, and 0 set boot option
Configuration Register Boot Field Value
Meaning
Use ROM monitor mode
(Manually boot using the b command)
Slide 2 of 4
Purpose:
Emphasize: Layer 2—Adds the table that identifies the boot field Configuration Register values and meanings. The first value, 0x0, enters ROM monitor mode. Your students should not enter this mode except for password recovery. Refer students to the Doc CD Rom or the “Installation and Maintenance of Cisco Routers (IMCR)” hardware course for more details.
0x0

17. Configuration Register Values
Router#configure terminal
Router(config)#config-register 0x2102
[Ctrl-Z]
Router#reload
Configuration register bits 3, 2, 1, and 0 set boot option
Configuration Register Boot Field Value
Meaning
Use ROM monitor mode
(Manually boot using the b command)
Slide 3 of 4
Purpose:
Emphasize: Layer 3—Adds the second boot field value 0x1. This setting automatically boots the system from ROM and provides a subset of the Cisco IOS image (Rxboot mode). Routing is not enabled in the Rxboot mode. However, the router has IP functionality in the Rxboot mode. For example, from the Rxboot mode, the router can perform a tftp transfers to copy an IOS image from a tftp server to its flash memory.
Some routers can store a full IOS image in ROM.
0x0
Automatically boot from ROM
(Provides IOS subset)
0x1

18. Configuration Register Values
Router#configure terminal
Router(config)#config-register 0x2102
[Ctrl-Z]
Router#reload
Configuration register bits 3, 2, 1, and 0 set boot option
Check configuration register value with show version
Configuration Register Boot Field Value
Meaning
Use ROM monitor mode
(Manually boot using the b command)
Slide 4 of 4
Purpose:
Emphasize: Layer 4—Finishes with the third case, a boot field setting in the range of 0x2 to 0xF. The entry of a Configuration Register value in the 0x2 to 0xF range is significant. When the router attempts to boot from the net (Netboot), the bootstrap program generates an IOS filename based on the value of the boot field. For example, with the setting 0x2, the default IOS filename generated will be cisco2-xxxx, where xxxx refers to a processor name (for example, 2500). Again, refer students to the IMCR course for details.
You use the config-register command to change the value.
Notice that the bottom lines of the show version output indicates what the value the config register will be on the next reload.
0x0
Automatically boot from ROM
(Provides IOS subset)
0x1
Examine NVRAM for boot system commands (0x2 default if router has Flash)
0x2 to 0xF

19. Loading the IOS from Flash
RAM
IOS
Flash
Console
Slide 1 of 1
Purpose:
Emphasize:
Note: The 2500 series routers do not operate this way. The 2500 series routers normally run IOS from flash. The IOS in flash is not compressed but it is relocatable. Relocatable means the IOS image can be ran from flash or from RAM.
The 2500 can run from RAM if you use the “boot system tftp” command to boot the IOS image.
The Rxboot mode is also ran from RAM on the 2500 routers.
IOS
show flash
Flash file is decompressed into RAM

20. show flash Command wg_ro_a#sh flash System flash directory:
File Length Name/status
c2500-js-l_120-3.bin
[ bytes used, available, total]
16384K bytes of processor board System flash (Read ONLY)
Slide 1 of 1
Purpose:
Emphasize:
Note:
The current state of the flash memory is in Read ONLY mode. It is running IOS from flash.
This router has a total of 16MB of flash memory. The flash contains one IOS image and there are 6.69MB available space left in flash.

21. Loading the Configuration
RAM
NVRAM
Config
Config
IOS
show
running-config
show
startup-config
Console
Slide 1 of 1
Purpose:
Emphasize: Using the default config register value (0x2102), the router will load the config from NVRAM at startup.
Setup utility
Load and execute config from NVRAM
If no config in NVRAM, enter setup mode

22. show running and show startup Commands
In RAM
In NVRAM
wg_ro_c#show running-config
Building configuration... Current configuration: ! version 12.0 !
-- More --
wg_ro_c#show startup-config
Using 1359 out of bytes !
version 12.0
-- More --
Slide 1 of 1
Purpose: This slide is a repeated slide from chapter 4.
Emphasize:
Display current and saved configuration

23. Sources of Configurations
RAM
NVRAM
copy running startup
Config
Config
copy startup running (merge)
Slide 1 of 4
Purpose:
Emphasize: When copying to RAM, it is always a merge not an overwrite.
Explain on the board the difference between a merge versus an overwrite.
Explain the general syntax of the copy command: copy <from> <to>
With 12.0, the copy command supports a new syntax. The new syntax is explained in a later slide.
NVRAM

24. Sources of Configurations
RAM
NVRAM
copy running startup
Config
Config
copy startup running (merge)
config term
(merge)
Slide 2 of 4
Purpose:
Emphasize:
NVRAM
Terminal

25. Sources of Configurations copy startup running (merge)
RAM
NVRAM
copy running startup
Config
Config
copy startup running (merge)
config term
(merge)
copy tftp run
(merge)
Console
Slide 3 of 4
Purpose:
Emphasize:
Note:
The Cisco TFTP server software which runs on Windows 95/98/NT can be downloaded from the url listed below:
A Cisco router can also be configured to be a tftp server using the “tftp-server” global configuration command.
copy tftp start
copy run tftp
NVRAM
Terminal
TFTP server
copy start tftp
TFTP server

26. Sources of Configurations
RAM
NVRAM
copy running startup
Config
Config
copy startup running (merge)
config term
(merge)
erase start
copy tftp run
(merge)
Console
Slide 4 of 4
Purpose:
Emphasize:
copy tftp start
Blank
000000
NVRAM
Terminal
TFTP server
Erase Start
copy run tftp
copy start tftp
TFTP server

27. copy run tftp and copy tftp run Commands
wg_ro_a#copy running-config tftp
Address or name of remote host []?
Destination filename [running-config]? wgroa.cfg
.!!
1684 bytes copied in secs (129 bytes/sec)
wg_ro_a#copy tftp running-config
Source filename []? wgroa.cfg
Destination filename [running-config]?
Accessing tftp:// /wgroa.cfg...
Loading wgroa.cfg from (via Ethernet0): !
[OK /3072 bytes]
1684 bytes copied in secs (99 bytes/sec)
Slide 1 of 1
Purpose:
Emphasize: Note: Release 12.0 supports new syntax for the “copy” command.

28. Cisco IOS File Systems and Devices
RAM
NVRAM
system:
nvram:
Slide 1 of 1
Purpose:
Emphasize: In release 12.0, there are new copy commands. These new commands treat the RAM, Flash, NVRAM, tftp, ftp, etc… as a file system. Since at the time when this class was developed, the most common IOS in the field is pre 12.0, these 12.0 commands are not covered in detail in this class.
Flash
TFTP server
flash:
tftp:

29. Managing IOS Images Network server Router Network server
c2500-js-l_120-3.bin
Network server
Router
Slide 1 of 1
Purpose:
Emphasize: This section introduces topics on managing your configuration file and IOS image.
FLASH
Network
server

30. Preparing for a Network Backup Image
Network server
Router
Check access to the server
Slide 1 of 4
Purpose: This slide establishes an overview and reason to use the TFTP server as a load source or backup destination for Cisco IOS software. It then presents the preparation details needed before executing TFTP copies.
Emphasize: Geographically distributed routers need a source or backup location for software images. Using a network server allows image and configuration uploads and downloads over the network. The network server can be another router, a workstation, or a host system.
A router can be configured as a tftp server using the tftp-server global configuration command.
Layer one - First, you need to check that you have access to the network server. Example, use the ping command to see if you can reach the server.

31. Preparing for a Network Backup Image
Network server
Router
Check access to the server
Check space available on the server
Slide 2 of 4
Purpose:
Emphasize: Layer 2 — you need to check that you have enough disk space on the tftp server to house the new system image. On the router, use the show flash command to determine the length of the IOS image.

32. Preparing for a Network Backup Image
c2500-js-l_120-3.bin
Network server
Router
Check access to the server
Check space available on the server
Check file naming convention
Slide 2 of 4
Purpose:
Emphasize: Layer 3 — you need to check the naming conventions required on the server. Example, what is the max number of characters allowed in the filename by the server’s O.S? What is the max number of characters allowed in the filename extension by the server’s O.S?

33. Preparing for a Network Backup Image
c2500-js-l_120-3.bin
Network server
Router
Check access to the server
Check space available on the server
Check file naming convention
Create file on server if required
Slide 4 of 4
Purpose:
Emphasize: Layer 4—On some Unix server, you may have to first create the file first before you can download the IOS image from the router to the tftp server. You can use the “touch” Unix command to create an empty file on the Unix server.

34. Verifying Memory and Deciphering Image Filenames
wg_ro_a#show flash
System flash directory:
File Length Name/status
c2500-js-l_120-3.bin
[ bytes used, available, total]
16384K bytes of processor board System flash (Read ONLY)
Verify Flash memory has room for the IOS image
Slide 1 of 1
Purpose:
Emphasize: The show flash command is an important tool to use to gather information about your router memory and image file. Caution students that they must know that they are loading the correct and appropriate image. The name for the Cisco IOS image file contains multiple parts, each with a specific meaning:
The first part of the image name contains the platform on which the image runs. In this example, the platform is C2500.
The second part of the name identifies the special capabilities of the image file. A letter or series of letters identifies the feature sets supported in that image. In this example, the j indicates this is an enterprise image, and the s indicates it contains extended capabilities.
The third part of the name specifies where the image runs and if the file is compressed. In this example, l indicates the file is relocatable and not compressed. Relocatable means the IOS can be ran from flash or from RAM. You should be careful in reading the Cisco IOS image filename. Some fonts display the lowercase letter “l” and the number 1 as the same character. How you type the characters will impact the ability of the router to load the files correctly.
The fourth part of the name indicates the version number. In this example, the version number is 12.0 (3).
The final part of the name is the file extension. The .bin extension indicates this file is a binary executable file.
The Cisco IOS software naming conventions, name part field meaning, image content, and other details are subject to change. Refer to Cisco Connection Online (CCO) for updated details.

35. Creating a Software Image Backup
FLASH
Network
server
copy flash tftp
wg_ro_a#copy flash tftp
Source filename []? c2500-js-l_120-3.bin
Address or name of remote host []?
Destination filename [c2500-js-l_120-3.bin]?
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
<output omitted>
bytes copied in secs (14223 bytes/sec)
wg_ro_a#
Slide 1 of 1
Purpose: This slide discusses how to create a backup version of a Cisco IOS software image to a tftp server.
Emphasize: Routers by default comes with Flash memory that have a preloaded copy of the Cisco IOS software. Although Flash is extremely reliable—good for 65 years and 100,000 rewrites—it is a good idea to make a backup copy of the Cisco IOS software if you have a tftp server available. If you had to replace Flash memory for some reason, you would have a backup copy at the revision level currently running on your network.
The copy command screen output varies depending on the Cisco IOS software level.
Determine the platform type of your tftp server prior to beginning the backup procedure. The tftp server may be running Windows, UNIX, Mac or other O.S . Filename and directory access procedures may vary depending on the tftp server platform and platform version.
Back up current files prior to updating Flash

36. Upgrading the Image from the Net
FLASH
Network
server
wg_ro_a#copy tftp flash
Address or name of remote host [ ]?
Source filename []? c2500-js-l_120-3.bin
Destination filename [c2500-js-l_120-3.bin]?
Accessing tftp:// /c2500-js-l_120-3.bin...
Erase flash: before copying? [confirm]
Erasing the flash filesystem will remove all files! Continue? [confirm]
Erasing device... eeeee (output omitted) ...erased
Erase of flash: complete
Loading c2500-js-l_120-3.bin from (via Ethernet0): !!!!!!!!!!!!!!!!!!!!
(output omitted)
[OK / bytes]
Verifying checksum... OK (0x9AA0)
bytes copied in secs (32636 bytes/sec)
wg_ro_a#
Slide 1 of 1
Purpose: This slide describes how to load a backup version of a Cisco IOS software image from a tftp server to the router.
Emphasize: If you need more flash space to load a copy of the Cisco IOS software, then you must first erase the Flash memory. You cannot erase a single image—you must erase all copies of Cisco IOS software from Flash. However, if Flash memory on the router is partitioned, you can erase one or more of the parts.
After the tftp transfer is completed, use the show flash command to view the file size to compare its size with that of the original on the server.
If the IOS is running from flash, then the flash is in the read only state. To change the flash to a writeable state: you can use the boot system tftp command to boot an IOS from a tftp server and the IOS will be ran from RAM or you can go to the Rxboot mode to perform the copy.
Erase Flash occurs before loading new image
Note message that image already exists

37. Cisco IOS User Interface Overview
The CLI is used to enter commands.
Operations vary between routers and switches, but both use the same CLI.
Users may type or paste entries within the console configuration modes.
Configuration modes have distinctive prompts.
Two primary EXEC modes are user mode and privileged mode.
Changes are not saved automatically.
Purpose: This slide introduces the two Cisco IOS EXEC modes on the Catalyst 1900 switch and routers.
Emphasize: As you present this, describe the bullet points that can prepare your students to work with the Cisco IOS user interface.

38. Overview of Cisco IOS Configuration Modes
Emphasize: Here is a list of some of the configuration modes available.
For a complete list of the router configuration modes, refer to the Cisco Documentation CD-ROM.

39. Help Facilities of the Cisco IOS CLI
Purpose: This slide describes the Help facilities on the Catalyst 1900 switch.
Emphasize: After showing how to log in to the Catalyst 1900 Cisco IOS CLI and enabled EXEC privileged mode, use this slide to present the three main types of command-line help available.
This list is similar to, but not as extensive as the types of command-line help on the router that you present later with a similar slide.
If at this point you can demonstrate what you are presenting, so much the better.
The help on the switch is very similar to the help on the router, so the details are only presented once, in the router section.