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WHAT IS A LAN? What does LAN stand for ? Local Area Network..

What is a LAN and what is it used for? a LAN is 2 or more computers are in the same area e.g. a LAN can be used in schools, at work and at home allowing each client to share the same resources e.g. applications, data, games. It is basically used so that client that are near each other in a certain amount of area are able to access the internet and sometimes share resources. .E.g. setting up a LAN at home will enable everyone client in the house to be able to access the internet.

I use our school LAN to access my H: drive which is where I save things I need, I also use the school printer to print off any work that I need. And the s: drive is student shared. In the screen shot THSDC is the server. It is there so students can access shared files.

A printer, laptop, PCs and mobile devices all can be connected to a LAN if they all have an network interface card.

WHAT IS A MAN?MAN stands for Metropolitan Area Network. WAN stands for Wide Area Network. LAN stands for Local Area Network.

A metropolitan is a network that is different from a LAN because a MAN network can connect larger areas to the internet. Which can range from several blocks of buildings to another city.

A MAN interconnects an amount of LANs to a WAN (Wide Area Network) no matter where they are.

The best example of a WAN is the internet, or when networks span countries.So basically what a WAN does is when a MAN picks up any network links across regional or national boundaries the MAN will need to connect it to the internet and this is where the WAN comes in.

ATLANTA CITY BOSTON CITY

BRAZIL - COLOMBIA

PEER TO PEER

A peer to peer is a computer network that can act as their own client or server allowing other computer’s on the network to share files and have access to what every other client has. The unique characteristic with this architecture is every client is an equal.

A P2P is mainly used for small businesses or at home, because it can only connect a small amount such as 10 computers anymore then 10 will cause the peer to peer to act ridiculously slow and sometimes not at all this is why a client/server is more powerful and also why a peer to peer is used for smaller businesses .

CLIENT/SERVER?A client/server is a LAN architecture that connects a reasonable amount such as 10 or more computers together and they share the same resources. On this LAN, a machine will either be a server or a client, not both. A client/server LAN is mainly used for larger businesses because of the number of machines and devices that need to access resources.

The server is dedicated to serve what ever the other clients request directly to them not through another machine and is able to take on a big load of requests all at once and still work fine because it has been built to do so. Its hardware specifications is better and the operating system more able. This is why it is more powerful than a peer to peer.

CHARACTERISTICS OF A CLIENT/SERVERSize: a client/server is commonly used for large businesses because It is able to handle large numbers of network devices, while being able to act fast on the network by dishing out requests being made all at once even if it receives a big pile of requests it can do all this without any problems.

Performance: it has been built to handle more clients than a peer to peer because of the switches used as an example, one switch could connect up to 24 devices. The server also is spec's with failsafe hard drives that have larger capacities that are faster e.g. scsii.

Cost: a client/server is more expensive to set up than a peer to peer for example an enterprise switch brand is Cisco and they wouldn’t cost anything less than thousands of dollars, and that’s just one switch! An enterprise router such as Cisco 800 series router is more secure and faster as well.

Security: the security on a client/server is safer than a Peer to peer too because there is only one administrator and it gives less access to other people that are logged on. So basically when someone logs onto a computer the computer will know what that person can have access to and what not to expose to that person so client/server security is more secure than a Peer to Peer. Plus it does this more securely. e.g. Windows Server can allow someone to restrict internet access based on user groups.

CHARACTERISTICS OF A PEER TO PEER

Size: a p2p is used for a small amount of computers (5 – 10) over 10 would cause the computer network to act ridiculously slow because the hardware and operating system of the client machines is not designed to be a server.

Performance/speed: it works fine for a smaller amount of clients that should be connected to the p2p it doesn’t work too well when you exceed the appropriate amount. The only way to know how many is too many, would be to add more until you dislike the performance e.g. how long it takes to open a shared file or save.

Cost: a peer to peer is less expensive than a client server. A peer to peer is the least expensive because you can purchase devices at Dicksmith without enterprise labels such as Cisco. You could configure a LAN at home for less than a thousand dollars.

Security: since every computer is able to act as their own client/server security is very serious because who ever may be logged on at any time will then be the administrator giving them the power to access files, create passwords share or unshare resources.

WHAT NETWORK COMPONENTS ARE BEST

PEER TO PEER CLIENT/SERVERHub Switch Modem Router

Network attached storage Fileserver

Fiber cable

Can be used on both LANSMobile Devices

Laptops

PCs

Wireless devices

Printer

CAT5 cable

HUBA hub has multiple input/output ports this one has 8 ports you can connect to.

a input is signals of data being received and an output is signals of data being sent from it.

The ports are used to connect devices that you want to share such as a computer and a printer

A hub would be better to use on a Peer to peer because the hub has 8 ports and is not as smart as a switch is.

SWITCHSwitches allow multiple devices to connect to the ports

The way a switch works is like the way a hub works but the switch is more efficient because a switch pays attention to the traffic it learns where the message comes from and who it is to it learns where certain addresses are e.g. when a switch receives a message for example the switch send out the message to all the ports in use instead of computer “A” like a hub does BUT the switch has learned the connection location the sender. So when computer "A” replies the switch will know where to send the message because it know the connection location of the sender and from this it has learned the connection location of computer “A”. So just from this the switch has learned the connection location for the sender and computer “A” which allows the switch to work more faster and easier. This is why a switch is more powerful than hub. And because I the power a switch has it is recommended for medium to large businesses

NETWORK STORAGEA network attached storage can be located anywhere on LAN. This is how network storage works, there is a server and all that does is processes all the data and what the NAS does is delivers the data to the user. A NAS allows more hard disk space storage to be added to the network.

All a hard disk is just a magnetic disk that allows you to store data on it. The word “hard” steers it away from the disk been soft. A hard disk is better because it stores more data and faster than a floppy disk . A hard disk can store anywhere from 10 to 100 gigabytes. Compared to a floppy disk which ca candle to a maximum of data storage of 1.4 megabytes.

ROUTERA router is the smartest out of a hub and a switch, a router can come in many shapes and sizes from a small four port internet broadband router which is popular now a days to the industrial strength router that steers the internet itself.

All a router does basically is directs traffic and works almost exactly like a Switch learns the locations of the traffic that it directs it pays attention like a switch but the router is the most complicated out of a hub and a switch it is more complex.

The way a router operates it routes traffic so it basically manages and directs traffic to its destination. It is like a switch it learns by paying attention to the traffic learning the location of the computer through its connections.

A switch is like a computer that can be programmed to analyze and almost manipulate the data that it is been requested to handle. This is why a router would be recommended for larger businesses

ADVANTAGES & DISADVANTAGES OFCOAXIAL.

Coaxial advantages:• coaxial has quite a large frequency range which allows it to carry multiple signals.• each channel has a greater bandwidth that allows high quality definition.• the shield reduces any interference, allowing more cable length between

amplifiers.Coaxial disadvantages:• it is more expensive to install and it uses network topology that is prone to

congestion ???????

ADVANTAGES & DISADVANTAGES OFCAT5 (5E OR 6)

CAT 5 advantages:• CAT 5 is one of the cheapest cabling options and has remained so.• CAT 5 is able to transfer up to 4 signals all of them at once. And has high transfer

speeds towards older cabling and personal networks.• Is capable to perform various tasks, CAT5 cabling has 2 forms one form is the

solid conductor it, it connects the wall socket and the other standard CAT5

CAT 5 disadvantages:

http://www.ehow.com/list_6184254_advantages-disadvantages-cat-5-cables.html

ADVANTAGES & DISADVANTAGES OFFIBRE CABLING

Fibre cabling Advantages:Fibre Cabling disadvantages:

ADVANTAGES & DISADVANTAGES OFWIRELESS

Wireless advantages:Wireless Disadvantages:

WHAT IS AN IP ADDRESS?Every single machine on the network has an identifier and that is called an IP address so the network can identify your computer when you want to send a email to another computer or something like that just like when you send a written letter you address the letter.

You can get your IP address 2 ways either static or dynamic. A static Address is when you construct your own by editing your computer settings, this is very rare and the problem with it is it can cause network problems for you if you don’t have a good understanding of TCIP/IP (The communications Protocol/ Internet Protocol. A Dynamic Address is when DHCP (Dynamic Host Configuration Protocol) assigns your computer a IP address. DHCP is a service running on the network hardware e.g. Routers or Servers dedicated to DHCP.

An IP Address is critical on a LAN because without a IP address your computer wouldn’t be able to communicate because the network and other computers can only identify you through your number and if you don’t have one then you obviously won’t be recognised and without recognition your computer won’t be able to communicate.

IP ADDRESS PARTSExample of what it looks like is 192.168.0.2

This is an example of a class C address the same as what we have at school. There are also other classes reserved ranging from class A to E.

The 192.168.0 is the network part of the address and will be the same for every device on that LAN. The .2 is unique to each device otherwise they would conflict and stop working

CSMA/CDCSMA/CD stands for carrier sense multiple access collision detection. The CSMA is when there are a bunch of clients connected to a LAN and they are all sending requests and the CD part is when it detects when there is a collision happening so when there is a client that is wanting to request something the CSMA/CD lets the computer listen within the cable for any buzzing sounds which are collisions and if there isn’t a collision then the request is sent out but if there is then the CSMA/CD puts the request on hold until there is no buzzing noise its just silent and then it send the request. If there were 2 computers waiting until there are no more collisions and both computers send out the request at the same time there will be a collision so it will resend.

This is why CSMA/CD is important on a LAN because it stops collisions and stops data loss.

Refer to next slide for flow chart.

PCI 1 PCI 2

Carrier Sense

“listening to the Ethernet”

Clear

MULTIPLE ACCESS Try to Transmit

Collision detection

Did a collision occur ?

YES NO

Jam signal

Retransmit after random period of

time

There are 3 types of data transmissions the best way that you can understand the way these 3 different data transmissions work are to think of them as a high way.

Simplex: data can flow only one way between sender and receiver, like one way road. Half duplex: data can flow both ways on a two way road just not at the same time.

Full duplex: data can flow both ways at the same time and can send more information at once. This is why this is the preferred mode of transmission for equipment on your LAN.

DATA TRANSMISSION

OSI: Open System InterconnectionIt is a standard description on how data should be transmitted between ay two point s in a LAN network. The reference model consists seven layers to which are:TCP/IP: Transmission Control Protocol Internet ProtocolWhen a client is on the network it needs a IP address so it can communicate, and the TCP/IP gives out the IP addresses to clients if the client has chosen the dynamic address which is when the client asks the TCP/IP to assign it a IP address because it needs one to be able to communicate with other clientsDHCP: Dynamic Host Configuration ProtocolNAT: Network Address TranslationICMP: Internet Control Message protocol

Layer 7: The application layer...This is the layer at which communication partners are identified, quality of service is identified, user authentication and privacy are considered, and any constraints on data syntax are identified. (This layer is not the application itself, although some applications may perform application layer functions.)Layer 6: The presentation layer...This is a layer, usually part of an operating system, that converts incoming and outgoing data from one presentation format to another (for example, from a text stream into a popup window with the newly arrived text). Sometimes called the syntax layer.Layer 5: The session layer...This layer sets up, coordinates, and terminates conversations, exchanges, and dialogs between the applications at each end. It deals with session and connection coordination.Layer 4: The transport layer...This layer manages the end-to-end control (for example, determining whether all packets have arrived) and error-checking. It ensures complete data transfer.Layer 3: The network layer...This layer handles the routing of the data (sending it in the right direction to the right destination on outgoing transmissions and receiving incoming transmissions at the packet level). The network layer does routing and forwarding.Layer 2: The data-link layer...This layer provides synchronization for the physical level and does bit-stuffing for strings of 1's in excess of 5. It furnishes transmission protocol knowledge and management.Layer 1: The physical layer...This layer conveys the bit stream through the network at the electrical and mechanical level. It provides the hardware means of sending and receiving data on a carrier

WIRED VS WIRELESSWired advantages: a wired LAN is more faster and secure and has less faults than a wireless LAN sometime a Wireless LAN can’t reach areas where a wired LAN can e.g. Thick walls. Wired LANs can not be interfered with by a wireless telephone like a wireless LAN can

Wired disadvantages: a wired LAN is more difficult and expensive to set up because you have to drill holes in the wall running cables can also have an unpleasant look as all the cords are just hanging there. You can only use the LAN where the socket is so you can not go out side to use it.

Wireless Advantages: when wireless has been properly set up you can connect to the internet ranging from your location out to 300 metres. And as for the looks wireless saves the unattraction of all the cables in a bunch and tangled

Wireless Disadvantages: the performance is not as fast and is not as secure as wired because if you connected to a hackers laptop they will be able to read all your stuff e.g. your username your password... And wireless has a few weaknesses such as a wireless can not reach through thick walls and can also can have interferences with microwaves and wireless telephones. And at times you will not have a good connection to the internet and sometimes you may not be able to access the internet because of the poor reception

Model/protocol Acronym Definition Why is it important on a LAN

OSI Open system interconnection

TCP/IP Transmission Control Protocol/Internet Protocol

DHCP Dynamic Host Configuration Protocol

NAT Network Address Translation

ICMP Internet Control Message

Bus topology: on a LAN when you are using a bus topology each machine is connected to a long cable known as a backbone which connects all devices to the network. And the computers connect to the single bus through drop lines. A terminator is needed to stop signals bouncing back and fourth through the single bus cable.

Star topology: on a LAN when you are using a star topology the star allows all the computers on the network to have a point to point link to the hub which means all the computers there own separate access link to the hub instead of sharing a link this is good because it prevents collisions. The advantages are it is the less expensive, if one link fails only that link is affected other links remains active still. The disadvantages are it is more expensive because the cost of the hub, when the hub fails the whole system fails with it.

There are many different topologies, a topology is the way a computer network is structured. It is how the data flows within a network. There are 4 common topologies

Ring topology: on a LAN when you are using a ring topology has a cable that connects all the nodes ,which is a device that sends receives or processes data, enclosing the ring. So when a client sends a data packet it passes it onto the next active client if it is addressed to that client if not then it passes it on to the next node/client until it reaches back to the originating node and at this point it is discarded. But if it is addressed to that node then that node that has received the data packet copies it. since the ring topology has the ability to regenerate data packet it is able to span further distances than a star and bus topology. Hybrid topology: a hybrid topology is all the topologies above put together all in one.