Internet Protocol (IP) – This term refers to the movement of packets of data from node to node. The IP forwards each ‘packet’ to a destination address and this can be a certain web site. The Internet authorities like the ISP’s, assign ranges of numbers to different organizations and users. The IP is known as the unique identification code in which a particular computer is using in order to access the World Wide Web.
The Internet Protocol was developed to create a Network of Networks, the Internet.
Sockets – This is the name given to the package of subroutines that provide access to TCP/IP on most systems.
Each technology has its own convention for transmitting messages between two machines within the same network. On a LAN/WAN, messages are sent between machines by supplying the six byte unique identifier, IP address.
Open Systems Interconnect Seven Layer Model
To the right is the OSI Seven layer model and below is a description of alll of the separate layers.
The OSI model describes the flow of data in a network, from the lowest layer (the ‘Physical Connections’ layer) up to the layer containing the user’s applications.
· The Application layer represents the level at which applications access network services. This is where the real work actually gets done. This layer represents the services that directly support software for file transfers, database access, and electronic mail.
· The Presentation layer translates data from the Application layer into a go-between format. This layer manages security issues by like data encryption and compressing of data.
· The Session layer allows two applications on different computers to establish and end a session. This layer creates a control system between the two computers in a session, regulating which side transmits and how long it transmits.
· The Transport layer handles errors. It also repackages long messages when necessary into small packets for transmission and, at the receiving end, rebuilds packets into the original message. The receiving Transport layer also sends receipts.
· The Network layer gives each message an address and translates logical addresses and names into physical addresses. It also determines the route from the source to the destination computer and manages traffic problems, such as switching, routing, and controlling the data packets.
· The Data Link layer packages raw bits from the Physical layer into frames. This layer is responsible for transferring frames from one computer to another. After sending a frame, it waits for an acknowledgment from the receiving computer.
· The Physical layer transmits bits from one computer to another and regulates the transmission of a stream of bits over a physical medium. This layer defines how the cable is attached to the network adapter (Coaxial etc.) and what transmission technique is used to send data over the cable.
Data going to and from the network is passed layer to layer. Each layer is able to communicate with the layer immediately above it and the layer immediately below it. This way, each layer is written as an efficient, streamlined software component. When a layer receives a packet of information, it checks the destination address, and if its own address is not there, it passes the packet to the next layer.
Communication Channels
A communication channel refers to the various methods that a particular media can be used for. In this case it is the different methods in which the internet can be used for. The communication channel is a crucial part of the communication network.
Internet Applications
A complete set of application layer programs are available for use on the internet. These can be using internet technology or be internet applications directly, like a browser. However, each application program type is associated with its own application ‘protocol’. The application layer is just another protocol layer in the OSI model, the programs interface with application layer protocols.
I will describe the most popular applications and discuss there corresponding protocol;
- The World Wide Web (internet) uses; HTTP Protocol
The two popular web browsers which are required to ‘surf’ the internet are Microsoft Internet Explorer and Netscape Navigator. The look and feel of the two programs is very different but both work with the HTTP application layer protocol.
- Email programs, support the POP3 protocol
Programs like Outlook Express, Eudora etc. use the POP3 application layer protocol to send electronic mail, although there are exceptions like Hotmail, which are web based email providers.
- File utility programs use the FTP protocol
This protocol is used for copying and moving files between remote sites.
- Peer to Peer programs can use various protocols
Programs like Kazaa use P2P technology to share media across the network. Depending on the program, the protocol can be FTP, HTTP or the most common, TCP/IP!
- The Telnet protocol provides the ability to access other computers remotely using a Daemon software
Terminal Emulation (Telnet) is software that is used across various networks that allows remote access, and is made up of a Telnet server (Remote Host) and the client PC (Local Host). Telnet programs are a type of terminal emulation program, just like modem-based communications programs. The difference is that they allow you to access other computers through the Internet, rather than by dialing the other computers directly. Telnet programs "talk" to other Internet-connected computers using what's called the "telnet protocol" for communication. This protocol specifies how telnet programs should send data back and forth, allowing for interactive text sessions.
An example of the Telnet environment being put into use is found out at;
Domain Name System
The Domain Name System (DNS) is an Internet directory service. DNS is used to translate between domain names and IP addresses, and to control Internet email delivery. Most Internet services rely on DNS to work, and if DNS fails, web sites cannot be located and email delivery fails or pauses. A computers IP address is its DNS, in which it can be identified.
The Internet however, is really based on IP addresses. Every time you use a domain name, a DNS service must translate the name into the corresponding IP address. For example, the domain name www.snowboard.com might translate to 198.105.232.4.
The DNS system is kind of, its own network. If one DNS server doesn't know how to translate a particular domain name, it asks another one, and so on, until the correct IP address is returned.
Client Servers and Peer to Peer networks
Client Server
Within a client server environment, a software program is needed, like Windows NT or Novell. Files are stored on a main high speed server! This computer is known as the file server and will be connected to all of the client PC’s.
All network services like printers and email are routed through one machine, the file server, which allows close monitoring of all activities on client machines. Both user data and network applications are kept on this PC, so modifying a particular program will only have to be done on the one machine.
ALL operations are sent through the file server even if a client PC wants to communicate with another client PC; a message must be sent to the server and routed in a separate process.
Peer to Peer (P2P) Networking
A peer to peer (P2P) network allows two or more PC’s to gather all their resources together for sharing. These could be files or devices, like CD drives and hard disks. They are configured so that they are shared resources and that they can be accessed from any other PC that might be connected to the P2P.
Instead of network information being kept on one machine, like client server networks, the information and resources are stored across the entire P2P network. This information is stored on the users own hard disk and shared to any other machine on the network. This means that each PC acts as both a client and a server.
Each PC can communicate directly with each other and share each others resources.
Main Differences;
- Network access speeds in client servers are usually faster than those found on P2P.
- Client servers can support vast numbers of PC’s, as a result of the architecture.
- P2P clients can communicate directly to each other.
- Client server networks can be monitored through one machine, the file server.
- In a P2P network each PC can make backups for security purposes.
- The file server on the Client server can improve efficiency and can easily update software on one machine instead of ‘x’ amount of PC’s.
- If a client PC wants to communicate directly with another client PC, it will have to be routed through the file server, which is not as efficient as a direct connection.
- In P2P, no network administrator is needed.
- P2P networks are fast and not expensive to build or maintain.
- P2P can be used at both home and for businesses.
