2. Objectives
• Explain what is router and difference between
hardware and software router.
• Understand different modes of router.
• Understand different components of router.
• Familiar with different commands used to configure
router.
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3. Router
Routers are very common today in every network area,
this is mainly because every network these days connect
to some other network, whether it's the Internet or some
other remote site.
Routers route the data from one network to another.
There are two types of router:
1. Hardware Routers:
2. Software Routers.
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4. Router contd..
Hardware Routers
They are small boxes which run special software created
by their vendors to give them the routing capability and the
only thing they do is simply route data from one network to
another.
Software Routers
Software routers do the same job with the above hardware
routers (route data), but they don't come in small flashy
boxes.
A software router could be an NT server, NetWare server
or Linux server. All network servers have built-in routing
capabilities.
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6. Software Routers contd..
You cannot replace the hardware router with a software
router.
Hardware router has the necessary hardware built-in to
allow it to connect to the special WAN link (frame relay,
ISDN, ATM etc), where your software router (e.g a NT
server) would have a few network cards one of which
connects to the LAN and the other goes to the WAN via
the hardware router.
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7. Components of Router
The basic components of any Cisco router are as
follows:
1. Interfaces
2. The Processor (CPU)
3. Internetwork Operating System (IOS)
4. RXBoot Image
5. RAM
6. NVRAM
7. ROM
8. Flash memory
9. Configuration Register
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8. Components of Router contd..
Interfaces
The interfaces are the various serial ports or Ethernet ports
which we use to connect the router to our LAN.
There are a number of different interfaces.
Here are some of the names Cisco has given some of the
interfaces:
E0 (first Ethernet interface), E1 (second Ethernet
interface).
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9. Components of Router contd..
The Processor (CPU)
The CPU generates interrupts (IRQ) in order to
communicate with the other electronic components in the
router.
Internetwork Operating System (IOS)
The IOS is the main operating system on which the router
runs.
The IOS is loaded upon the router's bootup.
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10. Components of Router contd..
RXBoot Image
The RXBoot image (also known as Bootloader) is nothing
more than a "cut-down" version of the IOS located in the
router's ROM (Read Only Memory).
RAM
The RAM (Random Access Memory), is where the router
loads the IOS and the configuration file.
It works exactly the same way as your computer's
memory, where the operating system loads along with all
the various programs.
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11. Components of Router contd..
NVRAM (Non-Volatile RAM)
The NVRAM is a special memory place where the router
holds its configuration.
ROM (Read Only Memory)
The ROM is used to start and maintain the router.
It contains some code, like the Bootstrap and POST, which
helps the router do some basic tests and bootup when it's
powered on or reloaded.
You cannot alter any of the code in this memory as it has
been set from the factory and is Read Only.
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12. Components of Router contd..
Flash Memory
It is an EEPROM (Electrical Eraseable Programmable
Read Only Memory) card. It fits into a special slot normally
located at the back of the router and contains nothing more
than the IOS image(s).
Configuration Register
The Configuration Register determines if the router is
going to boot the IOS image from its Flash, tftp server or
just load the RXBoot image.
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13. Router Modes
You have noticed that the lower end routers (600-1400)
use different commands than the mid to upper range
routers (1600 and above).
Setup Mode
The setup mode is a step-by-step process which helps you
configure basic aspects of the router.
When using this setup mode, you actually have
two options:
• Basic Management Setup
• Extended Setup
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14. Router Modes contd..
Configuration Mode
Cisco routers have different configuration modes
(depending on the router model).
They are as follows:
• User Exec Mode (>)
• Privileged Mode (#)
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15. User Exec Mode
The easiest way to keep track of the mode you're in is by
looking at the prompt.
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16. Privileged Mode
To get into Privileged Mode we enter the "Enable"
command from User Exec Mode.
Global Configuration
The following figure shows you how to enter Global
Configuration Mode:
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17. Privileged Mode contd..
Generic Configuration
There are a few standard things with which you always
need to configure the router.
This is also used as a login name for the remote router to
which your router needs to authenticate.
Configuring Interfaces
We have a router with one Ethernet and one basic ISDN
interface (max of 128Kbit).
In order to configure the interface, we need to be in Global
Configuration Mode.
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