Basic of Networking

8/3/2019 Basic of Networking

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Local Area Network (LAN)

- LAN are Networks within a single Buildingor campus of up to few kilometres in size.

- They are widely used to connect personal computers

and workstations in company Offices to share resources

like files and printers

- Traditional LANs run at speed of 10 Mbps to 100 Mbps

Newer LANs operate at up to 10 Gbps

Metropolitan Area Network ( MAN)

- Refers to Network of computers with in a city

- An example will be cable networks


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Wide Area Network (WAN)

- Wide area networking combines multiple LANsthat are geographically separate.

- This is accomplished by connecting the differentLANs using services such as dedicated leased

phone lines, dial-up phone lines (both synchronousand asynchronous), satellite links.

- Wide area networking can be as simple as amodem and remote access server for employees todial into, or it can be as complex as hundreds ofbranch offices globally linked using special routingprotocols and filters to minimize the expense ofsending data sent over vast distances.


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Internet

- The Internet is a system of linked networks that areworldwide in scope and facilitate data communicationservices such as remote login, file transfer, electronicmail, the World Wide Web and newsgroups.

Intranet

- An intranet is a private network utilizing Internet-type tools, but available only within that

organization. For large organizations, an intranetprovides an easy access mode to corporateinformation for employees.


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Two Categories of Network

- Peer to Peer- Server Based

- In peer-to-peer networking there are no dedicated servers orhierarchy among the computers.

- All of the computers are equal and therefore known as peers.Normally each computer serves as Client/Server and there isno one assigned to be an administrator responsible for theentire network.

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The term Client/server refers to the concept of sharing thework involved in processing data between the client computerand the most powerful server computer.


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Open System Interconnection (OSI) reference model

has become an International standard and servesas a guide for networking.

This model is the best known and most widely used

guide to describe networking environments.Vendors design network products based on thespecifications of the OSI model.

It provides a description of how network hardwareand software work together in a layered fashion tomake communications possible


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OSI Model Has Seven Layers


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Physical Layer

- Physical layer is just that the physical parts of the network

such as wires, cables, and there media along with the length.

Also this layer takes note of the electrical signals thattransmit data throughout system.

Data Link Layer

- Input datas are sent in data frames and transmit the frames

sequentially

- this layer will allow and define the error detection and

correction schemes that insure data was sent and received.


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Network Layer

- Key design issue is determining how packets are routed

from source to destination

- This layer provides the definition for the connection of twodissimilar networks.

Transport Layer

- Basic function of this layer is to accept data from above,

split it up into smaller units if needed and pass to thenetwork layer

-This layer allows data to be broken into smaller packages fordata to be distributed and addressed to other nodes(workstations).


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Session Layer

- Session layer allows Users on different machines to

establish session between them

- A session has to be made before we can transport

information to another computer.

Presentation Layer- This layer is responsible to code and decode data sent to

the node

- Presentation layer is concerned with Syntax and semanticsof the information transmitted


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Application Layer

- this layer allows you to use an application that will

communicate with say the operation system of a server

- Application layer contains a variety of protocols that

are commonly needed for users

- One widely used application protocol is HTTP (Hyper text

transfer protocol which is basics for world wide web.

- Another example will be SMTP protocol (Simple mailtransfer protocol), IMAP ( Internet Message Access protocol)

POP3 (Post Office protocol used for Electronic Mail.


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Magnetic Media- Disks and tapes are one of the most popular methods of transmittingdata from one computer to another fast. The problem is that the sourceand destination have to be very close together for this to be reasonable.If you need to transmit your data to another town in less time than itwould take to drive there, then another method of transfer will be

needed.

Twisted Pair- Twisted Pair wiring (Cat 3 and Cat 5) are popular methods oftransferring data. They are especially prevalent in the LAN environment.The twists allow the signal to travel further than it could on a regular

copper wire. The more twists per centimeter, the further the signal cantravel. This is why Cat 5 wire (with more twists) is preferred over Cat 3wire. Twisted pair wires consist of two strands of copper twistedtogether; the wires are unshielded, which is why Twisted Pair wire is alsocalled Unshielded Twisted Pair (UTP).


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Coaxial Cable

- Coaxial Cable is an insulated copper wire covered with amesh conductor, with a coating of plastic on top of that.

- One advantage of coax over other types of transmission lineis that in an ideal coaxial cable the electromagnetic field

carrying the signal exists only in the space between the innerand outer conductors.
http://en.wikipedia.org/wiki/Electromagnetic_fieldhttp://en.wikipedia.org/wiki/Electrical_conductorhttp://en.wikipedia.org/wiki/Electrical_conductorhttp://en.wikipedia.org/wiki/Electromagnetic_field


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Fiber Optics


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Network topologies are categorized into the

following basic types

Bus

Ring

Star

Tree

Mesh


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Bus

-Bus network use a common backbone to connect all devices

- A device wanting to communicate with another device onthe network sends a broadcast message onto the wire that allother devices see, but only the intended recipient actuallyaccepts and processes the message.


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Advantages of a Linear Bus Topology- Easy to connect a computer or peripheral to a linear bus.

- Requires less cable length than a star topology.

Disadvantages of a Linear Bus Topology- Entire network shuts down if there is a break in the main

cable.- Terminators are required at both ends of the backbonecable.

- Difficult to identify the problem if the entire network shutsdown.

- Not meant to be used as a stand-alone solution in a largebuilding.


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Ring- In a ring network, every device has exactly two neighbors

for communication purposes. All messages travel through aring in the same direction (either "clockwise" or"counterclockwise").

- A failure in any cable or device breaks the loop and can take

down the entire network.

- Ring topologies are found in some office buildings orschool campuses


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Star

- Many home networks use the star topology. A star networkfeatures a central connection point called a "hub" that may bea hub, switch or router.
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Advantages of a Star Topology- Easy to install and wire.- No disruptions to the network when connecting or removingdevices.

- Easy to detect faults and to remove parts.

Disadvantages of a Star Topology- Requires more cable length than a linear topology.

- If the hub or concentrator fails, nodes attached are

disabled.

- More expensive than linear bus topologies because of thecost of the concentrators.


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Tree

- Tree topologies integrate multiple star topologies togetheronto a bus.- In its simplest form, only hub devices connect directly tothe tree bus, and each hub functions as the "root" of a tree ofdevices. This bus/star hybrid approach supports future

expandability of the network much better than a bus


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Advantages of a Tree Topology- Point-to-point wiring for individual segments.

- Supported by several hardware and software venders.

Disadvantages of a Tree Topology- Overall length of each segment is limited by the type of

cabling used.

- If the backbone line breaks, the entire segment goes down.

- More difficult to configure and wire than other topologies.


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Mesh

- Mesh topologies involve the concept of routes

- Messages sent on a mesh network can take any of severalpossible paths from source to destination.

- Some WANs, most notably the Internet, employ meshrouting.
http://compnetworking.about.com/cs/lanvlanwan/g/bldef_wan.htmhttp://compnetworking.about.com/cs/lanvlanwan/g/bldef_wan.htm

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