welcometocomputernetworks-100907004628-phpapp02.ppt

computer networking

1. NETWORKINGNETWORKING
INTERCONNECTION OF INTERCONNECTION OF
COMPUTERSCOMPUTERS

2. What is computer network?What is computer network?
A network is group of computers A network is group of computers
interconnected with each other to exchange interconnected with each other to exchange
information or resource.information or resource.
A computer network is collection of A computer network is collection of
interconnected autonomous computers interconnected autonomous computers
interconnected in a single technology.interconnected in a single technology.
Two computers are said to interconnected with Two computers are said to interconnected with
each other if they share some information each other if they share some information
between them.between them.

3. What are the advantages of having What are the advantages of having
computer network?computer network?
1.Increased communication capabilities.1.Increased communication capabilities.
2.File sharing: Network offer quick and easy way to share files directly at a rapid 2.File sharing: Network offer quick and easy way to share files directly at a rapid
speed thus saving time and integrity of files.speed thus saving time and integrity of files.
3.Resouce sharing : All computers in a network can share resources like printer, 3.Resouce sharing : All computers in a network can share resources like printer,
scanner, modem, fax machines, hard disk.scanner, modem, fax machines, hard disk.
4. 4. Security: Security: Specific directories can be password protected to limit access to Specific directories can be password protected to limit access to
authorized users. Also, files and programs on a network can be designated as "copy authorized users. Also, files and programs on a network can be designated as "copy
inhibit" so you don’t have to worry about the illegal copying of programs.inhibit" so you don’t have to worry about the illegal copying of programs.
5. It is also possible to share data files across the network by creating a share on the 5. It is also possible to share data files across the network by creating a share on the
hard drive and allowing other people access to that information. hard drive and allowing other people access to that information.
6.Increases the productivity.6.Increases the productivity.
7. You can connect all the computers which are connected through a network to the 7. You can connect all the computers which are connected through a network to the
internet by using a single line. So it means that you can save the connection cost for internet by using a single line. So it means that you can save the connection cost for
each computer but you internet connection must be fast. each computer but you internet connection must be fast.
8. 8. Internet connection sharingInternet connection sharing - Using a home network, multiple family members - Using a home network, multiple family members
can access the Internet simultaneously without having to pay an can access the Internet simultaneously without having to pay an ISP for multiple for multiple
accounts. You will notice the Internet connection slows down when several people accounts. You will notice the Internet connection slows down when several people
share it, but broadband Internet can handle the extra load with little trouble. Sharing share it, but broadband Internet can handle the extra load with little trouble. Sharing
dial-up Internet connections works, too. dial-up Internet connections works, too.
 oror
Connect your entire office to the Internet through one line. Connect your entire office to the Internet through one line.

4. What are the disadvantages of What are the disadvantages of
computer network?computer network?
1.Network faults can cause loss of data.1.Network faults can cause loss of data.
2.Network faults could lead to loss of resources.2.Network faults could lead to loss of resources.
3.Systems open to hackers.3.Systems open to hackers.
4.Could become inefficient.4.Could become inefficient.
5.Could degrade to performance.5.Could degrade to performance.
6.Resources could be located too far from users.6.Resources could be located too far from users.
7.As a work group user cannot Login from other 7.As a work group user cannot Login from other
work group machine within LAN network.work group machine within LAN network.
8.User also cannot login from any remote machine 8.User also cannot login from any remote machine
from WAN environment.from WAN environment.

5. What are the different types of What are the different types of
computer networks?computer networks?
PAN( personal area network) : Network that is meant for one personPAN( personal area network) : Network that is meant for one person
Eg: A wireless network connecting a computer with it’s mouse, keyboard, Eg: A wireless network connecting a computer with it’s mouse, keyboard,
printer is PAN. Covers 1m distance only.printer is PAN. Covers 1m distance only.
LAN (local area network) : LAN’s are privately owned network which LAN (local area network) : LAN’s are privately owned network which
covers a room, building or a campus ( 10m, 100m, 1km) of distance.covers a room, building or a campus ( 10m, 100m, 1km) of distance.
LAN’s are widely used in offices, companies, industries.LAN’s are widely used in offices, companies, industries.
Characteristics:Characteristics:
* Lan’s are restricted in size* Lan’s are restricted in size
*Lan’s uses transmission media as cable , to which all the machine are *Lan’s uses transmission media as cable , to which all the machine are
attached.attached.
*Lan’s basically uses Bus and Ring Topologies( network structure) to *Lan’s basically uses Bus and Ring Topologies( network structure) to
broadcast. broadcast.
Traditional Lan’s runs at the speed of 100Mbps and newer Lan’s runs at Traditional Lan’s runs at the speed of 100Mbps and newer Lan’s runs at
the speed of 10Gbps.the speed of 10Gbps.
Lan’s are un-switched ( they don’t have routers). Lan’s are un-switched ( they don’t have routers).

6. MAN (metropoliterian area network): MAN covers city MAN (metropoliterian area network): MAN covers city
( about 10Km) in distance.( about 10Km) in distance.
The best example of Man is the CABLE TV NETWORK The best example of Man is the CABLE TV NETWORK
available .available .
Cable TV is not the only MAN ,development in high speed Cable TV is not the only MAN ,development in high speed
wireless internet access resulted in MAN.wireless internet access resulted in MAN.
MAN’s are also un-switched ( i.e don’t have routers)MAN’s are also un-switched ( i.e don’t have routers)
WAN (wide area network): A wide area network covers a WAN (wide area network): A wide area network covers a
large geographical areas like country or a continent ( about large geographical areas like country or a continent ( about
100Km, 1000Km, 10,000Km)in distance.100Km, 1000Km, 10,000Km)in distance.
In WAN, subnet consist of two components Transmission In WAN, subnet consist of two components Transmission
lines like copper cable, optical fiber ( move bits between lines like copper cable, optical fiber ( move bits between
machines) and Switching elements or routers (specialized machines) and Switching elements or routers (specialized
computers or devices that connects 3 or more transmission computers or devices that connects 3 or more transmission
lines, when date arrives to incoming line, router choose an lines, when date arrives to incoming line, router choose an
outgoing line on which to forward them.outgoing line on which to forward them.

7. Hosts ( user’s computers) are connected to subnet.Hosts ( user’s computers) are connected to subnet.
Subnet is owned and operated by telephone company or isp.Subnet is owned and operated by telephone company or isp.
The subnet is collection of communication lines and routers The subnet is collection of communication lines and routers
( but not hosts).( but not hosts).
The job of subnet is to carry message from host to host .The job of subnet is to carry message from host to host .
In most WAN’s , the network contains numerous In most WAN’s , the network contains numerous
transmission lines , each one connecting pair of router. If transmission lines , each one connecting pair of router. If
two routers do not share a transmission line , wish to two routers do not share a transmission line , wish to
communicate they must do this indirectly via other router .communicate they must do this indirectly via other router .
When a packet is sent from one router to another via one or When a packet is sent from one router to another via one or
more intermediate routers, the packet is received at each more intermediate routers, the packet is received at each
intermediate router in its entirety , stored until the required intermediate router in its entirety , stored until the required
output is free, and then forwarded. output is free, and then forwarded.
This principle is known as “store and forward or packet This principle is known as “store and forward or packet
switched subnet”.switched subnet”.

8. What are the types of transmission What are the types of transmission
media ?media ?
Signals are usually transmitted over some transmission media that are Signals are usually transmitted over some transmission media that are
broadly classified in to two categories.broadly classified in to two categories.
Guided Media:Guided Media:
These are those that provide a conduit from one These are those that provide a conduit from one devicedevice to another that to another that
include twisted-pair, coaxial include twisted-pair, coaxial cablecable and fiber-optic cable. A signal traveling and fiber-optic cable. A signal traveling
along any of these media is directed and is contained by the physical limits along any of these media is directed and is contained by the physical limits
of the medium. Twisted-pair and coaxial cable use metallic that accept and of the medium. Twisted-pair and coaxial cable use metallic that accept and
transport signals in the form of electrical current. Optical fiber is a glass or transport signals in the form of electrical current. Optical fiber is a glass or
plastic cable that accepts and transports signals in the form of light.plastic cable that accepts and transports signals in the form of light.
Unguided Media: Unguided Media:
This is the wireless media that transport electromagnetic waves without This is the wireless media that transport electromagnetic waves without
using a physical conductor. Signals are broadcast either through air. This is using a physical conductor. Signals are broadcast either through air. This is
done through radio communication, satellite communication and cellular done through radio communication, satellite communication and cellular
telephony.telephony.

9. What are the different types of What are the different types of
network hardware?network hardware?
NIC ( network interface card)NIC ( network interface card)
Repeater Repeater
SwitchSwitch
RouterRouter
HubHub
ModemModem
ServerServer
GatewaysGateways
BridgesBridges
firewallfirewall

10. History of computer networkHistory of computer network
In 1969,a network called ARPANET (advanced research In 1969,a network called ARPANET (advanced research
project agency) was created. For transmission lines of 56kb project agency) was created. For transmission lines of 56kb
dedicated line.dedicated line.
In 1970, DECNET (digital electronic corporation network) In 1970, DECNET (digital electronic corporation network)
was created . For proper trait design.was created . For proper trait design.
In 1977-83, ETHERNET was created . Network In 1977-83, ETHERNET was created . Network
capacity10Mhz. Support token ring topology.capacity10Mhz. Support token ring topology.
In 1981, a network called TCP/IP (transmission control In 1981, a network called TCP/IP (transmission control
protocol/internet protocol) was created. To support LAN and protocol/internet protocol) was created. To support LAN and
WAN. Which lead to the beginning of INTERNET.WAN. Which lead to the beginning of INTERNET.
In 1980’s , GIGA BYTE network was created. To support In 1980’s , GIGA BYTE network was created. To support
applications such as FTP, SMTP, HTTP, POP3, IMAP4.applications such as FTP, SMTP, HTTP, POP3, IMAP4.

11. NIC (network interface card)NIC (network interface card)
Also known as Lan card ,Ethernet card, Network/Ethernet adaptor.Also known as Lan card ,Ethernet card, Network/Ethernet adaptor.
It is an interface between computer and network cables.It is an interface between computer and network cables.
Functions of LAN card are,Functions of LAN card are,
*Data transfer*Data transfer
*Buffering data construction*Buffering data construction
 *Medium access control*Medium access control
*Encoding and decoding*Encoding and decoding
*Data transmission and reception*Data transmission and reception
Lan cards are full duplex ( they can send and receive data )Lan cards are full duplex ( they can send and receive data )
Lan card can have UTP, BNC, AUI ports.Lan card can have UTP, BNC, AUI ports.
Lan card puts packet on the cable.Lan card puts packet on the cable.
It contains MAC address.It contains MAC address.

12. What is MAC address?What is MAC address?
MAC (media access control ) 48-bit number MAC (media access control ) 48-bit number
(6-byte).Unique to each and every Lan card , (6-byte).Unique to each and every Lan card ,
represented in hexadecimal notation.represented in hexadecimal notation.
This address is used for communication at low This address is used for communication at low
level.level.
This address comes from manufacturer.This address comes from manufacturer.
Securities are based on MAC address.Securities are based on MAC address.

13. What is an IP?What is an IP?
IP (Internet protocol) is a method or protocol by which data is IP (Internet protocol) is a method or protocol by which data is
sent from one computer to another computer on the internet.sent from one computer to another computer on the internet.
Each computer on the internet has at least one IP address that Each computer on the internet has at least one IP address that
uniquely identifies it from all other computer on the internet.uniquely identifies it from all other computer on the internet.
When you send or receive data ( for example , an e-mail or When you send or receive data ( for example , an e-mail or
web page), the message gets divided into little chunks called web page), the message gets divided into little chunks called
packets.packets.
Each of these packets contains both senders internet address Each of these packets contains both senders internet address
(IP address) and the receivers address.(IP address) and the receivers address.
Any packet is sent first to gateway computer that understands Any packet is sent first to gateway computer that understands
a small part of internet.a small part of internet.

14. The gateway computer reads the destination address and The gateway computer reads the destination address and
forwards the packet to an adjacent gateway that in turn read forwards the packet to an adjacent gateway that in turn read
the destination address and so forth across the internet until the destination address and so forth across the internet until
one gateway recognizes the packet as belonging to one gateway recognizes the packet as belonging to
computer within its immediate neighborhood or domain.computer within its immediate neighborhood or domain.
The gateway then forwards the packet directly to the The gateway then forwards the packet directly to the
computer whose address is specified.computer whose address is specified.
Because message is divided into number of packets, each Because message is divided into number of packets, each
packet can, if necessary , be sent by a different route across packet can, if necessary , be sent by a different route across
the internet.the internet.
Packets can arrive in the different order they were sent in.Packets can arrive in the different order they were sent in.
The internet protocol just delivers them. It is up to other The internet protocol just delivers them. It is up to other
protocol, the TCP/IP to put back in the right order.protocol, the TCP/IP to put back in the right order.

15. What is IP address?What is IP address?
An IP address is an address with which a computer is identified on a network (internet).An IP address is an address with which a computer is identified on a network (internet).
An IP address is a logical address of the network adaptor.An IP address is a logical address of the network adaptor.
An IP address is a 32-bit number which has two parts network number and host number.An IP address is a 32-bit number which has two parts network number and host number.
 00001010000001110000010100000001
Computer won’t have problem in understanding this number but we as human can’t deal with binary.
An organization named IANA (internationally assigned numbering authority) as divided this 32-bit number into 4-octat and
has given the range from 0-255
 00001010- 00000111- 00000101- 00000001
An IP address in represented in decimal notation form like,
 192.168.1.1
Based on the range from 0-255 IANA has divided this 32-bit number into three classes,
Class A from 0-126
Class B from 128-191
Class C from 192-223
*127 is loopback address
*224-255 is for research and development purpose.
To manage and maintain network again IANA has divided each class of IP address into 2 parts,
*Network portion (N/P) –represented by 1’s
 *Host portion (H/P)- by 0’s
IANA has assigned class A with single octet (8-bits) for network portion and three octet (24-bits) for host portion.
IANA has assigned class B with two octet (16-bits) for network portion and two octets (16-bits) for host portion.
IANA has assigned class C with three octet (24-bits) for network portion and single octet (8-bits) for host portion.

16. IANA has assigned class A with single octet (8-bits) for network portion and three octet (24-bits) for host portion.IANA has assigned class A with single octet (8-bits) for network portion and three octet (24-bits) for host portion.
DSM (default subnet mask) : 255.0.0.0DSM (default subnet mask) : 255.0.0.0
IANA has assigned class B with two octet (16-bits) for network portion and two octets (16-bits) for host portion.IANA has assigned class B with two octet (16-bits) for network portion and two octets (16-bits) for host portion.
DSM (default subnet mask) : 255.255.0.0DSM (default subnet mask) : 255.255.0.0
IANA has assigned class C with three octet (24-bits) for network portion and single octet (8-bits) for host portion.IANA has assigned class C with three octet (24-bits) for network portion and single octet (8-bits) for host portion.
DSM (default subnet mask) : 255.255.255.0DSM (default subnet mask) : 255.255.255.0
A subnet mask defines network portion of ip address and host portion of ip address.By knowing the subnet mask A subnet mask defines network portion of ip address and host portion of ip address.By knowing the subnet mask
information, we can easily identify a particular machine ip belongs to which class.information, we can easily identify a particular machine ip belongs to which class.
IP Address is dividedinto two types:IP Address is dividedinto two types:
1. Private IP Address.1. Private IP Address.
2. Public IP Address.2. Public IP Address.
Private ip address are basically used within the LAN environment.All private ip address are free to use you don't have Private ip address are basically used within the LAN environment.All private ip address are free to use you don't have
to pay to any one for using these address.It is also known as Free IP Address.to pay to any one for using these address.It is also known as Free IP Address.
Private IP Address range:Private IP Address range:
Class A
  = 10.0.0.0  -  10.255.255.255
Class A
  = 10.0.0.0  -  10.255.255.255
Class B
  = 172.16.0.0 - 172.31.255.255
Class B
  = 172.16.0.0 - 172.31.255.255
Class C = 192.168.0.0 -
  192.168.255.255
Class C = 192.168.0.0 -
  192.168.255.255
Public IP Address:Public IP Address:
Public ip address are used in WAN environment.Used for connection to internet.Public ip address are not free , you Public ip address are used in WAN environment.Used for connection to internet.Public ip address are not free , you
need to pay for ip address (to isp or iana).need to pay for ip address (to isp or iana).
A part from above private ip address range from each and every class all the ip's are public ip's.A part from above private ip address range from each and every class all the ip's are public ip's.

17. What is HUB?What is HUB?
A HUB is a device which connects various machines in a A HUB is a device which connects various machines in a
network.network.
It’s major function is to replicate data it receives from one It’s major function is to replicate data it receives from one
device attached to it.device attached to it.
Hub is "Signal Splitter"Hub is "Signal Splitter"
Operates in "Physical Layer"Operates in "Physical Layer"
“Collisions” will occur in hub and it listen for collision “Collisions” will occur in hub and it listen for collision
domains.domains.

18.   Hub is “Hub is “Half-duplexHalf-duplex“(can receive or forward only)“(can receive or forward only)
  Also known as ” Concentrator”Also known as ” Concentrator”
 
 
 
 
Types,Types,
  PassivePassive (splitter) (splitter)
  ActiveActive (signal boosting) (signal boosting)
  IntelligentIntelligent (manageable) (manageable)

19. What is a switch?What is a switch?
A A switchswitch is a device which connects various systems in a network. is a device which connects various systems in a network.
Switch Switch maintains MAC address tablemaintains MAC address table..
Packets are directly transferred to the destination without Packets are directly transferred to the destination without
broadcasting.broadcasting.
Switch is considered as an Switch is considered as an intelligent deviceintelligent device..
In switch , In switch , each packet gets th same speedeach packet gets th same speed..
A A switchswitch is Full-duplex(can forward & receive simultanously) is Full-duplex(can forward & receive simultanously)
Packets are filtered by switches.Packets are filtered by switches.
No concept of collision domain or No concept of collision domain or No collisionNo collision as it is full duplex. as it is full duplex.
Works in “Works in “Data link layerData link layer” layer 2 and in layer 3” layer 2 and in layer 3
There are two types of switches,There are two types of switches,
1.1.Managable switchManagable switch –
 has console port,we can make configuration
–
 has console port,we can make configuration
2.2.Unmanagable switchUnmanagable switch – has no console port. – has no console port.

20. Cisco divided switches in 3 layers:Cisco divided switches in 3 layers:
1.1.Access layer switchesAccess layer switches : It works in layer 2 as it understands MAC : It works in layer 2 as it understands MAC
address only.It doesn’t understand IP address.Switches series – 1900 address only.It doesn’t understand IP address.Switches series – 1900
 
&  2900
 
&  2900
2.2.Distribution layerDistribution layer and 3. and 3.Core layer switchesCore layer switches: It works in layer 3 : It works in layer 3
because it understands MAC address as well as IP address. Switches because it understands MAC address as well as IP address. Switches
series – 7000 &
 10000.
series – 7000 &
 10000.
Distribution layer and core layer switches can access millions of Distribution layer and core layer switches can access millions of
packets per second
 
packets per second
 
-- whereaswhereas
 

 
-- Router can access 1 lakh packets per Router can access 1 lakh packets per
second.second.

21. What is Router?What is Router?
A A routerrouter is a device or a specialized computer
 which takes 
is a device or a specialized computer
 which takes 
data packets
  from  incomming lines, and  decides  outgoing
data packets
  from  incomming lines, and  decides  outgoing
lines on which to forward them.lines on which to forward them.
A A routerrouter is responsible for
 routing the data packets towards
is responsible for
 routing the data packets towards
their destination.their destination.
A A routerrouter is a device, which enables communication between is a device, which enables communication between
two different networks or enables communication between two two different networks or enables communication between two
different series/classes of network.different series/classes of network.
A A routerrouter is a internetworking device. is a internetworking device.
A A routerrouter routes the packet from one logical network to other routes the packet from one logical network to other
logical network.logical network.
It dealsIt deals with, finding the way to the destination. with, finding the way to the destination.

22. The The main jobmain job or function or function of routerof router is to calculate the best is to calculate the best
path/route for the packet to reach to it’s destination.
   or
path/route for the packet to reach to it’s destination.
   or
The main role of router is to determine the best path towards The main role of router is to determine the best path towards
destination.destination.
It determinesIt determines where the data should go on the physical where the data should go on the physical
network.network.
Types of Routers:Types of Routers:
There are two types of routers: There are two types of routers: Fixed routerFixed router and and Modular Modular
routerrouter
Fixed router:Fixed router:
1. Parts in the router are inbuilt where modification to 1. Parts in the router are inbuilt where modification to
theinterface is not possible.theinterface is not possible.
2. Access layer router
 are the  exmple of fixed router except
2. Access layer router
 are the  exmple of fixed router except
1600
  and  1700 series.
1600
  and  1700 series.
Modular Router:Modular Router:
1. Parts to the router can be added and removed i.e 1. Parts to the router can be added and removed i.e
modification to the interface is possible.modification to the interface is possible.

23. 2. Distribution and core layer router are the examples of 2. Distribution and core layer router are the examples of
modular router.modular router.
Cisco RoutersCisco Routers are divided into 3 catagories or layers: are divided into 3 catagories or layers:
1. Access Layer Router1. Access Layer Router
2. Distribution Layer Router2. Distribution Layer Router
3. Core Layer Router3. Core Layer Router
Access Layer routersAccess Layer routers are used by small organizations.Also are used by small organizations.Also
knownas
 desktop or company layer routers. Router that are
knownas
 desktop or company layer routers. Router that are
mostly used here are,router series – 800, 1000, 1600, 1700, mostly used here are,router series – 800, 1000, 1600, 1700,
2500.2500.
Distribution Layer routerDistribution Layer router are used by ISP’s .Also known as IS are used by ISP’s .Also known as IS
layer routers.Router series – 2600, 3200, 3600, 3700.layer routers.Router series – 2600, 3200, 3600, 3700.
Core layer routerCore layer router are used by global ISP’s .Also known as are used by global ISP’s .Also known as
backbone routers. Router series – 6400, 7200, 7300, 7400, backbone routers. Router series – 6400, 7200, 7300, 7400,
7500, 7600, 10000, 12000.
 
7500, 7600, 10000, 12000.
 

24. What is repeater?What is repeater?
Repeater is a device used to extend a network.Repeater is a device used to extend a network.
Extends the range of a network.Extends the range of a network.
Amplifies or regenerates the data signal, in Amplifies or regenerates the data signal, in
order to extend network.order to extend network.
Doesn’t amplify noise.Doesn’t amplify noise.
A repeater amplifies and cleans up digital A repeater amplifies and cleans up digital
signals and forwards their destination.signals and forwards their destination.

25. What is Modem?What is Modem?
It is a device, which converts binary code (from the computer) It is a device, which converts binary code (from the computer)
to the analog signal needed for transmitting messages over to the analog signal needed for transmitting messages over
telephone lines.telephone lines.
It does modulation-demodulation
 
It does modulation-demodulation
 
OrOr
A device used to convert digital signals into analog tones that A device used to convert digital signals into analog tones that
can be transmitted over the telephone network.
 
can be transmitted over the telephone network.
 
Types,Types,
*Internal Modem*Internal Modem
*External Modem*External Modem
*Card Version*Card Version

26. What is firewall?What is firewall?
* System that establish access control policies among * System that establish access control policies among
network.network.
* They can block information from entry.* They can block information from entry.
* A combination of hardware and software that * A combination of hardware and software that
protects a network from attack by hackers that could protects a network from attack by hackers that could
gain access through public network, including the gain access through public network, including the
internet.internet.

27. Different Types of TopologiesDifferent Types of Topologies
* Star topology* Star topology
* Bus topology* Bus topology
* Ring topology* Ring topology
* Token ring topology* Token ring topology
* Hybrid topology* Hybrid topology
* Mesh topology* Mesh topology
Topology means Structure of computer network or Design of computer
network.
Star topology:
In star topology all the systems are connected to a central device which
may be hub or switch.
Advantage: If one computer cable is broken or damage then other
computers will not be affected i.e Network is not affected.
Diadvantage: If central device (hub or switch) stops working then whole
company network is blocked (any system can’t communicate with each
other).

28. Bus Topology:Bus Topology:
In bus topology all the systems are connected to a single cable/channel or
back bone
 .Computers are connected with this cable using BNC connector
or T connector. At the both ends of cable
 Terminators are connected.
Advantage: Cheap
  and Easy to implement.
Disadvantage: If terminators are not connected or open then data will
bounce back.
Ring Topology:Ring Topology:
In ring topology each computer is connected to each other .ie every system
is connected
   to their next system in form of ring .
Advantage: Easy to install and easy to troubleshoot.
Disadvantage: If one of the computer goes down or if one of the cable
break between two machines then whole the network is down.Data packets
can’t go further.
Token Ring Topology:Token Ring Topology:
In token ring toplogy, all the systems are connected to a central
device
 ”MSAU”  multiple station access unit Hub.
Token ring is 802.5 standard.
Developed by IBMDeveloped by IBM
Has a unique token passing access method.Has a unique token passing access method.

29. Contains an “electronic signal” which constantly rotates in MSAU hub.
Here if one computer needs to send a packet to other then this packet from
source machine is taken or attached to token(electronic signal) and
forwarded or takes to the destination address machine.
Disadvantage: If this central device (MSAU)
  stops working or fails then
whole the company network is down or
 all the systems connected can’t
communicate with
 each other.

30. GatewaysGateways
A system that bridges two systems.
A computer connected with various computer, wants to
transfer a packet, can transfer directly to the router by giving
router address as gateway address at IP address portion.
 Gateways are used to connect two dissimilar LAN .
Gateways work in application layer of OSI model.
A gateway is required to convert data packets from one
protocol format to another before forwarding it, as it connects
two dissimilar networks.
Gateway Protocols:
Members of
  TCP/IP  protocol suite that routers use to
determine the best route
  for the data packets.
  

31. EthernetEthernet
Originally developed by Xerox corporation, that can link upto Originally developed by Xerox corporation, that can link upto
1024 nodes in bus network.1024 nodes in bus network.
A networking hardware , communication and cabling standard.A networking hardware , communication and cabling standard.
A high-speed standard using a base band (single channel) A high-speed standard using a base band (single channel)
communication technique.communication technique.
Ethernet Provides row data transfer rate of 10 Mbps.Ethernet Provides row data transfer rate of 10 Mbps.
Ethernet uses (CSMA/CD) to prevent network failures when Ethernet uses (CSMA/CD) to prevent network failures when
two devices try to access the network at the same time.two devices try to access the network at the same time.

32. What is the architecture of networking?What is the architecture of networking?
1. Peer to Peer (Point to Point):1. Peer to Peer (Point to Point):
Here each node acts as client as well as server.Here each node acts as client as well as server.
Hard disk, cd-rom, printer can be shared.Hard disk, cd-rom, printer can be shared.
Example:Example: windows2000, 9x windows2000, 9x
Sharing of file between two nodesSharing of file between two nodes
Nobody is server hereNobody is server here
Using desktop type of OS (XP) we can use peer to peer.Using desktop type of OS (XP) we can use peer to peer.
2. Client/ Server:2. Client/ Server:
Best example, Internet.Best example, Internet.
It can support more than one processor.It can support more than one processor.
Server- giving services, file sharing server, printing server.Server- giving services, file sharing server, printing server.
Example:Example: a demo video showing on server can be shared to all the a demo video showing on server can be shared to all the
machines in a network.machines in a network.
UNIX,
 windows, Linux dominates.
UNIX,
 windows, Linux dominates.
Used in large environment.Used in large environment.
One or more machine as dedicated server.One or more machine as dedicated server.