A Computer Network is a system in which computers are connected to share information and resources such as hardware and computer software. The connection can be done as peer-to-peer or client/server. In the world of computers, networking is the practice of linking two or more computing devices together for the purpose of sharing data.Computer Network helps the user to communicate,exchange information and share various devices that are connected to the network.Computer in a network may be connected using telephone lines,cables,satellite links etc.
Tuesday, September 1, 2009
group20_dynamic networks:how internet works ?
Internet is just a bunch of computers all over the world that are hooked together in a network. By going through the Internet, you can send and receive files (like webpages or MP3’s), read and send e-mails, and do many other useful (and not so useful) things.Each computer connected to the Internet must have a unique address called IP address. We generally get connection from ISP who gives us a unique IP address. We divide the information into smaller divisions called packets, and send the data a packet at a time over the wire until it reaches the destination computer. Protocols are different ways of communicating to the network of computers governing certain standard rules and procedures which facilitate communication between computers.Routing refers to the direction of data packets between two or more computers in a network. To convert the alphabetic text into electronic signals we use different protocol stack. A very large scale of inter-connected computers forming a web called World Wide Web which allows rich and diverse communication by displaying text, graphics, animation, photos, sound and video.
group2_old bridge:network protocol analysis
Network protocol analysis is a process for a program to decode network protocol headers and trailers to understand the data and information inside the packet encapsulated by the protocol. To conduct protocol analysis, packets must be captured at real time for line speed analysis or later analysis. Such program or device is called a Protocol Analyzer.
We first have to understand what is a network.
A computer network is a system in which computers are connected to share information . The connection can be done as peer-to-peer or client/server.
Peer-to-peer is a communications model in which each party has the same capabilities and either party can initiate a communication session.
On the Internet, peer-to-peer (referred to as P2P) is a type of transient Internet network that allows a group of computer users with the same networking program to connect with each other and directly access files from one another's hard drives like the very famous
picture source-cyberpunknet.blogspot.com
Napster(www.napster.com, en.wikipedia.org/wiki/napster) & the not so famous Gnutella(en.wikipedia.org/wiki/Gnutella)
Protocol-In information technology, a protocol is the special set of rules that end points in a network connection use when they communicate.
Its very interesting how they conferred it protocol.The word protocol is derived from the Greek word protocollon, which was a leaf of paper glued to a manuscript volume, describing its contents which is very similar to the rules that are being followed for communication in a network.
The tools that are used for network protocol analysis are called as network protocol analyzers example-Ethereal (www.ethereal.com/)& wireshark(www.wireshark.org/) which can also be used on windows platform
the screenshot of ethereal on windows platform
Picture source -ethereal.com
We first have to understand what is a network.
A computer network is a system in which computers are connected to share information . The connection can be done as peer-to-peer or client/server.
Peer-to-peer is a communications model in which each party has the same capabilities and either party can initiate a communication session.
On the Internet, peer-to-peer (referred to as P2P) is a type of transient Internet network that allows a group of computer users with the same networking program to connect with each other and directly access files from one another's hard drives like the very famous
picture source-cyberpunknet.blogspot.comNapster(www.napster.com, en.wikipedia.org/wiki/napster) & the not so famous Gnutella(en.wikipedia.org/wiki/Gnutella)
Protocol-In information technology, a protocol is the special set of rules that end points in a network connection use when they communicate.
Its very interesting how they conferred it protocol.The word protocol is derived from the Greek word protocollon, which was a leaf of paper glued to a manuscript volume, describing its contents which is very similar to the rules that are being followed for communication in a network.
The tools that are used for network protocol analysis are called as network protocol analyzers example-Ethereal (www.ethereal.com/)& wireshark(www.wireshark.org/) which can also be used on windows platform
the screenshot of ethereal on windows platform
Picture source -ethereal.comAs we can see in the picture, it analyses the protocol. Ethereal is used by network professionals around the world for troubleshooting, analysis, software and protocol development, and education.wireshark is a improved version of ethereal it can also be run on windows platform
picture sourceGroup13_Avani:How do you think LAN works?
A local area network (LAN) is a group of computers and associated devices that share a common communications line or wireless link and typically share the resources of a single processor or server within a small geographic area (for example, within an office building). A local area network may serve as few as two or three users (for example, in a home network) or as many as thousands of users (for example, in an FDDI network).
Major local area network technologies are:
1. Ethernet
2. Token Ring
3. FDDI (Fiber Distributed Data Interface)
Ethernet: Ethernet is the most widely-installed LAN technology. An Ethernet LAN typically uses coaxial cable or special grades of twisted pair wires. Ethernet is also used in wireless LANs.
Token Ring: The Token Ring is the second most widely-used protocol on local area networks after Ethernet. It is a LAN in which all computers are connected in a ring or star topology and a bit- or token-passing scheme is used in order to prevent the collision of data between two computers that want to send messages at the same time.
FDDI: Fiber Distributed Data Interface is a set of ANSI and ISO standards for data transmission on fiber optic lines in a LAN that can extend in range up to 200 km. FDDI is frequently used on the backbone for a wide area network (WAN).
Working of LAN: Various topologies are possible for broadcast LANs.
1. The first one is bus (i.e linear cable) network. In this at instant atmost one machine is the master and is allowed to transmit. All other machines are required to refrain from sending. An arbitration mechanism is needed to resolve conflicts when two or more machines want to transmit simultaneously.
2. The second one is ring. In a ring, each bit propagates around on its own, not waiting for the rest of the packet to which it belongs. Typically each bit circumnavigates the entire ring in the time it takes to transmit a few bits, often before the complete packet has even been transmitted.
Typically, a suite of application programs can be kept on the LAN server. Users who need an application frequently can download it once and then run it from their local hard disk. A user can share files with others at the LAN server; read and write access is maintained by a LAN administrator. A LAN server may also be used as a Web server. In some situations, a wireless LAN may be preferable to a wired LAN because it is cheaper to install and maintain.
Major local area network technologies are:
1. Ethernet
2. Token Ring
3. FDDI (Fiber Distributed Data Interface)
Ethernet: Ethernet is the most widely-installed LAN technology. An Ethernet LAN typically uses coaxial cable or special grades of twisted pair wires. Ethernet is also used in wireless LANs.
Token Ring: The Token Ring is the second most widely-used protocol on local area networks after Ethernet. It is a LAN in which all computers are connected in a ring or star topology and a bit- or token-passing scheme is used in order to prevent the collision of data between two computers that want to send messages at the same time.
FDDI: Fiber Distributed Data Interface is a set of ANSI and ISO standards for data transmission on fiber optic lines in a LAN that can extend in range up to 200 km. FDDI is frequently used on the backbone for a wide area network (WAN).
Working of LAN: Various topologies are possible for broadcast LANs.
1. The first one is bus (i.e linear cable) network. In this at instant atmost one machine is the master and is allowed to transmit. All other machines are required to refrain from sending. An arbitration mechanism is needed to resolve conflicts when two or more machines want to transmit simultaneously.
2. The second one is ring. In a ring, each bit propagates around on its own, not waiting for the rest of the packet to which it belongs. Typically each bit circumnavigates the entire ring in the time it takes to transmit a few bits, often before the complete packet has even been transmitted.
Typically, a suite of application programs can be kept on the LAN server. Users who need an application frequently can download it once and then run it from their local hard disk. A user can share files with others at the LAN server; read and write access is maintained by a LAN administrator. A LAN server may also be used as a Web server. In some situations, a wireless LAN may be preferable to a wired LAN because it is cheaper to install and maintain.
Group06_Bandwidth Brothers: Understanding Computer Networks
- Networking is a practice of linking various devices together with necessary hardware and software so as to facilitate communications between them. If the devices are computers, then it is called computer networking. Mostly data is transmitted or received between them. The technologies used to transmit can be broadly classified as Wired and Wireless. Wired includes popular technologies such as Telephone Cables, Ethernet Cables, Optical Fibres etc. Wireless includes Bluetooth, Infrared, Wifi, Wimax, 3G, gsm, gprs etc. Most popular type of computer networks are LAN,WAN,VPN and Internet. However there are other computer networks such as CAN,MAN,etc. Finally we need basic hardware equipments such as Network Interface Cards (NICs), bridges, hubs, switches and routers in order to facilitate computer networking. Data is transmitted between the computers through wires.
- Internet is considered as "baap" of all computer networks. In this network, all the computers participating have a unique address(such as the unique home address) known as IP (Internet Protocol) Adressses. This uniquely naming all the computers using numbers or hexadecimal chareters forms the basic stage in TCP/IP (the language with which the computers in Internet talk). It all happens when you order an internet connection to your home. The ISP (Airtel or BSNL) will provide you with the basic CPE(Consumer Premise Equipment) which will help you to connect to the Internet. When you type in a web address and hit enter in the browser, your request gets processed and sent into the DNS server which maintains the lookup tables for each web address. This lookup tables will then search for your entry and then the IP address will be retreived and the DNS server will then send a request to that web address. The information received from the web address will be forwarded to the client who requested that web address page. This is the general procedure followed while retreiving a world wide web address. There are many other protocols which use internet as the transmitting medium such a IRC, HTTP, FTP, Bittorrent etc.
group11_DNAA: how does internet work
Internet is a world wide system of computer networks in which users at any one computer can get information from any other computer. Each computer connected to internet must have a unique address called as an IP address. The message transfer between the computers is usually over wires. The message must be translated from alphanumeric text into electronic signals, transmitted over internet, then translated back to alphanumeric text. This is accomplished by using a protocol stack which is usually built into computer's OS. The protocol stack has four layers- application protocol layer, transmission control protocol layer, internet protocol layer, hardware layer.
The message would start at the top of the protocol stack on the computer and work its way downward. The message would be sent as chunks of data called packets. Each packet will have a port number. The IP layer would help to know the address of the destination computer. TCP layer helps to know which program on the destination computer needs to receive the message because it will be listening on a specific port. The hardware layer takes care of turning the packets containing the alphanumeric text of the message into electronic signals and thus transmitting it.The ISP router examines the destination address in each packet and determines where to send it. The packets start at the bottom of the destination computer's TCP/IP stack and work upwards. When the data reaches the top of the stack, the packets are reassembled into their original form.
One of the internet's major services is the World Wide Web. Web documents can be linked together because they are created in a format known as hypertext. Hypertext systems provide an easy way to manage large collections of data. To support hypertext documents the web uses a special protocol called Hypertext Transfer Protocol or HTTP. A hypertext document is an encoded file which uses the hypertext mark up language or HTML. This language allows a user to embed hypertext links or hyperlinks in the document. HTTP and hypertext links are the foundation of the World Wide Web.
The message would start at the top of the protocol stack on the computer and work its way downward. The message would be sent as chunks of data called packets. Each packet will have a port number. The IP layer would help to know the address of the destination computer. TCP layer helps to know which program on the destination computer needs to receive the message because it will be listening on a specific port. The hardware layer takes care of turning the packets containing the alphanumeric text of the message into electronic signals and thus transmitting it.The ISP router examines the destination address in each packet and determines where to send it. The packets start at the bottom of the destination computer's TCP/IP stack and work upwards. When the data reaches the top of the stack, the packets are reassembled into their original form.
One of the internet's major services is the World Wide Web. Web documents can be linked together because they are created in a format known as hypertext. Hypertext systems provide an easy way to manage large collections of data. To support hypertext documents the web uses a special protocol called Hypertext Transfer Protocol or HTTP. A hypertext document is an encoded file which uses the hypertext mark up language or HTML. This language allows a user to embed hypertext links or hyperlinks in the document. HTTP and hypertext links are the foundation of the World Wide Web.
group14_indigo:how do you think a LAN works?
LAN is the acronym for local area network. It is a private network . A small of group of computers within a building or campus is reffered to as LAN. These computers have a single administrator who is in charge of controling the file sharing, access and many other factors .
Each individual computer in a LAN has its own CPU and can execute its own programs and they can also acess data and devices anywhere on the LAN that is the user share expensive devices, printers, data etc.
The computer in a LAN can be arranged in a token ring, straight line, ethernet. Wireless LAN are infrared LAN, spread spectrum, narrowband microwave.
To create a LAN you need to use a structure in which the computer are each connected to the collector(hub) via the cable. The hub is a box to which one connects each of the PCs and that is incharge of routing the data from one PC to another. The choice of hub is based on a number of computers connected .
So far we have seen the working of wired LAN, now we shall see how data transmission takes place in wireless LAN
For wireless lan ,IEEE 802.11g standards are used. There are two basci layers for the transmission and reception of data.The data is sent in the form of frames the frame structure is as follows:
Each individual computer in a LAN has its own CPU and can execute its own programs and they can also acess data and devices anywhere on the LAN that is the user share expensive devices, printers, data etc.
The computer in a LAN can be arranged in a token ring, straight line, ethernet. Wireless LAN are infrared LAN, spread spectrum, narrowband microwave.
To create a LAN you need to use a structure in which the computer are each connected to the collector(hub) via the cable. The hub is a box to which one connects each of the PCs and that is incharge of routing the data from one PC to another. The choice of hub is based on a number of computers connected .
So far we have seen the working of wired LAN, now we shall see how data transmission takes place in wireless LAN
For wireless lan ,IEEE 802.11g standards are used. There are two basci layers for the transmission and reception of data.The data is sent in the form of frames the frame structure is as follows:
- frame control field(2 bytes)-Version of protocol
- address field-destination address
- frame body(contains data to be trasmitted
- frame check sequence(this is the last field,4 bytes)-receiver to perform error operations.
Finally
" LAN is like a drop in the ocean and internet is the ocean itself "
Group8_VintageBoys:How does LAN work
LAN: Local area network.
A local area network (LAN) supplies networking capability to a group of computers in close proximity to each other such as in an office building, a school, or a home.
LAN allows certain computers on the network to offer their resources such as printers, Hard disks, floppy, printers etc..for use by other computers on the network as if hey were their own.
The computer which provides resources are called as "SERVER" and the computer which uses is called as "WORKSTATIONS". If a computer works as a server and a workstation simultaneously it is called as peer and the network without dedicated server is called as peer-to-peer networks and in a dedicated server environment, its called a Client-Server based network.
How it works:
A LAN consists of two or more computers each equipped with a communication device called network interface or network adapter. Network interfaces are connected to one another by some type of communications medium, which provide
pathway for electrical signals that connect all of the computers on the LAN. The most widely used, cost-effective and highest performance network medium in use today is twisted pair ETHERNET CABLE. The transfer of data, file access are controlled by an administrator
Relatively new technology called wireless ethernet uses radio signal instead of copper cables.
For ex: Assume two computers, say COMPUTER A and COMPUTER B are connected by a LAN newtork, Computer A contains a CD ROM and Computer B doesn't have CD ROM, B wil be able to access A's CD ROM through LAN.
A local area network (LAN) supplies networking capability to a group of computers in close proximity to each other such as in an office building, a school, or a home.
LAN allows certain computers on the network to offer their resources such as printers, Hard disks, floppy, printers etc..for use by other computers on the network as if hey were their own.
The computer which provides resources are called as "SERVER" and the computer which uses is called as "WORKSTATIONS". If a computer works as a server and a workstation simultaneously it is called as peer and the network without dedicated server is called as peer-to-peer networks and in a dedicated server environment, its called a Client-Server based network.
How it works:
A LAN consists of two or more computers each equipped with a communication device called network interface or network adapter. Network interfaces are connected to one another by some type of communications medium, which provide
pathway for electrical signals that connect all of the computers on the LAN. The most widely used, cost-effective and highest performance network medium in use today is twisted pair ETHERNET CABLE. The transfer of data, file access are controlled by an administratorRelatively new technology called wireless ethernet uses radio signal instead of copper cables.
For ex: Assume two computers, say COMPUTER A and COMPUTER B are connected by a LAN newtork, Computer A contains a CD ROM and Computer B doesn't have CD ROM, B wil be able to access A's CD ROM through LAN.
Group15_krazzy4: Understanding computer networks
A computer network is a group of interconnected computers that enables the sharing of data and information between the computers. Computer networks have evolved over the years and is one of the hot spots of research in the Information Technology sector.
Computers can be connected in various ways to form a framework known as computer networks. Computer networks can be broadly classified into two categories according to the medium used to connect the devices forming the network i.e. wired and wireless . They can also be classified based on the area covered under them viz CAN,LAN,MAN,WAN . The devices constituting the network can be connected through hardware components such as Network interface cards,hubs,routers etc. The World Wide Web popularly known as internet has a foundation laid by the advent of computer networks.
Computers can be connected in various ways to form a framework known as computer networks. Computer networks can be broadly classified into two categories according to the medium used to connect the devices forming the network i.e. wired and wireless . They can also be classified based on the area covered under them viz CAN,LAN,MAN,WAN . The devices constituting the network can be connected through hardware components such as Network interface cards,hubs,routers etc. The World Wide Web popularly known as internet has a foundation laid by the advent of computer networks.
group18_awesum4sum: Stop and wait ARQ
Reliable transfer of communication is a critical requirement in communications between computers.One of them involves the ARQ ie Automatic Repeat re-Quest involves both identification of errors and retransmission to make sure that the data is received accurately by the user in spite of the various errors that occur during the transmission.
Stop and wait also known as bit banging protocol is one of the most simplest Automatic Repeat re-Quest method. In this method the sender sends one frame at a time and waits for an acknowledgment (ACK) from the receiver. If the receiver receives an uncorrupted frame an ACK is immediately sent. The errors in the frame are checked by the receiver using the redundancy bits added by the sender. Detection of an error is understood when the receiver does not send any ACK. In cases of errors the frame has to be resent to the receiver, but if the receiver does not respond when the error occurs the sender would not know if the frame has to be resent. In order to solve this the sender keeps a copy of the frame sent and starts of a timer once the frame is sent, if the sender does not receive the ACK within a specific duration of time (also known as time out) the sender sends the copy again.
Monday, August 31, 2009
MKN_Instructions for Blogging
General Instuctions:
Group 2_Famous Five:Network Protocol Analysers
Got it? This is for me to read your blog entries knowing which group has blogged on what topics in an organised way. Marks WILL BE deducted for groups who don't bother to adhere to rules, however good you are!
Lab Date: 02 Sep 2009, Time: 9 to 11 am -- Expectations
- Your batch is divided into project groups each having four students
- I have given atleast one invite to each group to blog here by collecting one email ID from each group.
- This "author" needs to login into his or her email box and accept the invitation.
- Next, you need to login to http://nwkjourney.blogspot.com/ using this emal ID
- Now...start collecting information...using "Google Guru" :-)
- Blog in a nice neat concise way what you have understood from the materials collected.
- Each group please name yourselves something.
- Each name MUST be UNIQUE
- Each Group will be numbered. There will I guess be 20 groups, so it will be Group 1, Group 2 .....till Group 20.
- Blog Title MUST be: "Group #_Group Name: Topic"
Group 2_Famous Five:Network Protocol Analysers
Got it? This is for me to read your blog entries knowing which group has blogged on what topics in an organised way. Marks WILL BE deducted for groups who don't bother to adhere to rules, however good you are!
Lab Date: 02 Sep 2009, Time: 9 to 11 am -- Expectations
- Atleast one paragraph on any of three Questions mentioned in 'Getting your Findas Cleared'
- More importance will be given to recording your understanding of Either Group A or Group B Mini Projects.
MKN_Topics for Blogging
*********************
Getting the "fundas" cleared
*********************
1. What is your understanding of Computer Networks?
2. How does Internet Work?
3. How do you think a LAN works?
*******************************************
Mini Projects Group A: Networking Tools
*******************************************
4. Record your Mini Project Group A Understanding
---P1. Protocol Stack and Addressing
---P2. Remote Login
---P3. FTP or Http Proxy Server
---P4. IP Utilities / Tcpdump
---P5. Network Protocol Analysers
---P6. Transmission Media
*******************************************
Mini Projects Group B: Programming
*******************************************
5. Record your Mini Project Group B Understanding
--- P7. Error Correction and Detection
--- P8. Stop and Wait ARQ
--- P9. Go Back N ARQ
--- P10. Selective Repoeat ARQ
*******************************************
Getting the "fundas" cleared
*********************
1. What is your understanding of Computer Networks?
2. How does Internet Work?
3. How do you think a LAN works?
*******************************************
Mini Projects Group A: Networking Tools
*******************************************
4. Record your Mini Project Group A Understanding
---P1. Protocol Stack and Addressing
---P2. Remote Login
---P3. FTP or Http Proxy Server
---P4. IP Utilities / Tcpdump
---P5. Network Protocol Analysers
---P6. Transmission Media
*******************************************
Mini Projects Group B: Programming
*******************************************
5. Record your Mini Project Group B Understanding
--- P7. Error Correction and Detection
--- P8. Stop and Wait ARQ
--- P9. Go Back N ARQ
--- P10. Selective Repoeat ARQ
*******************************************
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