A router is a networking device that connects different networks together and allows communication between them. It uses logical addressing like IP addresses to direct traffic between the networks. The document discusses different types of routers from Cisco including access layer routers for small networks, distribution layer routers for ISPs, and core layer routers for large backbones. It describes the various ports on a router like Ethernet, serial, console, and auxiliary ports and their purposes. The boot process of a router is also summarized where the ROM loads a bootstrap program from flash memory which then loads the IOS software and configuration from NVRAM into RAM.

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2. What is a Router ?
• Router is a device which makes communication
possible between two or more different networks
present in different geographical locations.
• To make communication possible between two or
more different networks present in the same
geographical location, what are the steps to be taken:
Answer : Configuring a Software Router or
Implementing the CIDR concept
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3. Is communication possible ?
10.0.0.1/8
S0
HYD
E0
192.168.1.150/24
LAN - 192.168.1.0/24
S1
10.0.0.2/8
CHE
E0
192.168.1.150/24
LAN - 192.168.1.0/24
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4. Is communication possible ?
The same networks present in different geographical
locations cant communicate through a router because
if Network ID of both the networks is same then the
request will not go out of the router and it’ll keep on
searching within the LAN.
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5. Which Routers to buy ?
Many companies are manufacturing Router :
• Cisco
• Nortel
• Multicom
• Cyclades
• Juniper
• Dlink
• Linksys
• 3Com
But Cisco is having monopoly in the market of
Routers
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6. Cisco’s Hierarchical Design Model
Cisco divided the Router into 3 Layers
• Access Layer Router
• Distribution Layer Router
• Core Layer Router
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7. Access Layer Router
• Routers which are used by the Small Organization
and are also known as Desktop or Company Layer
Routers.
Router Series : 800, 1000, 1600, 1700, 2500
Cisco 800
Cisco 1700
Cisco 1760
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8. Distribution Layer Router
• Routers which are used by the ISPs and are also
known as ISP Layer Routers
Router Series : 2600, 3200, 3600, 3700
Cisco 3600
Cisco 3700
Cisco 2600XM/2691
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9. Core Layer Router
• Routers which are used by the Global ISPs
and are also known as Backbone Routers
Router Series : 6400, 7200, 7300, 7400, 7500, 7600,
10000, 12000
Cisco 7000
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10. Router Classification
FIXED ROUTER
• Fixed Router are just
MODULAR ROUTER
• Modular Router are just
like a branded PC
like a Assembled PC
where modification of
where modification of
interfaces is not
interfaces is possible
possible
• Access Layer Routers
• Distribution and Core
are example of Fixed
Layer Routers example
Router except 1600
of Modular Router
and 1700 series
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11. Example Modular Router
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12. Model 2501
AUI
Attachment
Unit Interface
E0
Serial Ports
S0 and S1
Console
Con 0
Power Switch
Auxiliary
Aux 0
Power
Supply
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13. Attachment Unit Interface
• AUI pin configuration is 15 pin female.
• It is known as Ethernet Port or LAN port or
Default Gateway.
• It is used for connecting LAN to the Router.
• Transceiver is used for converting 8 wires to 15 wires.
i.e. RJ45 to 15 pin converter.
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14. Transceiver
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15. Attachment Unit Interface
An IP address needs to be assigned to this
An IP address needs to be assigned to this
interface and it should be in the same network as
interface and it should be in the same network as
of the LAN.
of the LAN.
E0
192.168.1.150/24
Straight Cable
Straight Cable
1.1
1.2
1.3
LAN - 192.168.1.0/24
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16. Attachment Unit Interface
Cross Cable
E0
192.168.1.150/24
If you connect Router AUI to
If you connect Router AUI to
directly to PC NIC Card then You
directly to PC NIC Card then You
have to use Cross Cable
have to use Cross Cable
1.1
LAN - 192.168.1.0/24
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17. Crimping of Twisted pair Cable
• Straight cable
It is used between unlike device (dissimilar devices)
e.g. Hub to PC, Switch to PC, Hub to Router
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12345678

18. Crimping of Twisted pair Cable
• Cross cable
It is used between like device (Similar devices)
e.g. Hub to HUB, PC to PC, Switch to Switch, HUB to
Switch, PC to Router
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19. Crimping of Twisted pair Cable
• Rollover Cable
It is used for connecting Router Console Port to PC
Com Ports or Serial ports.
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20. Serial Port
• Serial pin configuration is 60 pin configuration
female (i.e. 15 pins and 4 rows) and Smart Serial pin
configuration is 26 pin configuration female.
• It is known as WAN Port
• It is used for connecting to Remote Locations
• V.35 cable is having 60 pin configuration male at one
end and on the other end 18 pin configuration male.
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21. V.35 Cable
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22. V.35 Modem
E0
V.35
192.168.1.150 Cable
E0
192.168.2.150
V.35
Cable
2 pair of
Copper Wire
LAN - 192.168.1.0/24
LAN - 192.168.2.0/24
HYDERABAD
OFFICE
G.703
Modem
HYDERABAD
MUX
CHENNAI
OFFICE
EXCHANGE
G.703
Modem
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Fiber Optic Cable
CHENNAI
MUX

23. Console Port
• It is known as Local Administrative Port
• It is generally used for Initial Configuration,
Password Recovery and Local Administration of the
Router. It is RJ45 Port
• IMP : It is the most delicate port on the Router. So
make less use of the Console Port.
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24. Console Connectivity
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25. Console Connectivity
•
Connect a rollover cable to the router console port
(RJ-45 connector).
•
Connect the other end of the rollover cable to the
RJ-45 to DB-9 converter
•
Attach the female DB-9 converter to a PC Serial Port.
•
Open Emulation Software
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26. DB9 Converter
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27. Auxiliary Port
• It is known as Remote Administrative Port.
• Used for remote administration
• Its an RJ-45 port
• A console or a rollover cable is to be used.
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28. Auxiliary Connectivity
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29. Other Ports
• BRI Port
Basic Rate Interface used to connect ISDN to the
Router. It is a RJ45 Port. It is available on 2503 and
2520 model router.
• 10 Base T Port
It is a RJ45 Port and used for connecting LAN to the
Router. Its function is same as the AUI Port but there
is no need for a Transceiver. It is available on 2520
model router.
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30. 2601 Model Router
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31. Brief Overview
• WAN interfaces
– Serial interface (S0, S1 etc) – 60 pin/26 pin(smart serial)
– ISDN interface(BRI0 etc) – RJ45
• LAN interfaces - Ethernet
– AUI (Attachment Unit Interface) (E0)– 15 pin
– 10baseT – RJ45
• Administration interfaces
– Console – RJ45 - Local
– Auxiliary – RJ45 - Remote
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32. Internal Components
• ROM
A bootstrap program is located here. It is same as
the BIOS of the PC. Bootstrap program current
version is 11.0
• Flash
Internetwork Operating System (IOS) developed
by Cisco is stored here. IOS is Command line
interface.
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33. Internal Components
• NVRAM
Non volatile RAM, similar to Hard Disk
It is also known as Permanent Storage or Startup
Configuration. Generally size of NVRAM is 32 KB.
• RAM
It is also known as Temporary Storage or running
Configuration. Minimum size of RAM is 2MB. The
size of RAM is greater than NVRAM in the Router.
• Processor
Motorola Processor 70 Mhz, RISC based processor
(Reduced Instruction Set Computer)
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34. Internal Components
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35. Boot sequence
POST
ROM Power on Self Test
Power on Self Test
(verifies) the hardware
(verifies) the hardware
Contact the ROM
FLASH Contact the ROM
Loads the Bootstrap Program
Loads the Bootstrap Program
& Search where IOS is located
& Search where IOS is located
NVRAM IOS found in Flash
IOS found in Flash
Loading IOS
Loading IOS
RAM
Flash contacts the NVRAM
Flash contacts the NVRAM
For Configuration File
For Configuration File
NVRAM configuration copied
NVRAM configuration copied
into RAM
into RAM 35