Introduction to the Computer Network Architecture

What Is a Network?
Here you will learn about computer network architecture, physical design, logical topology, protocols introduction, communication planning and basic communication technologies. To properly build, maintain and secure a network you should first know that what a compute network is and how data travels through the wired or wireless network. A person with a good networking skills will be able to tell that a network consist of a computer, cables, PRI lines, Routers, switches, NIC cards, PBXs, TIs, fiber optic and Ethernet cables.  A person who have the strong background in the data network must know that a network consists of a server, workstations, routers, hubs, WAN, LAN, fiber optic and Ethernet cables and devices. Both the telecommunication and data communication persons agree that the cabling is an essential part of any computer network.The simplest definition of the data network is to connect two more computer computers with each other to share data and resources. The network exists in different sizes and shapes, from home networks to WAN networks. Despite the different roles and various sizes of a network you can have some common similarities in all the networks such as protocols, architecture and topology/design.

  Computer Network Architectures
Basically computer network architectures are dividing into three basic types such as LAN (local area network), MAN (Metropolitan area network) and WAN (wide area network. A LAN can consist of two or more computers in the same room or building. Fiber optic or Ethernet cables are used to connect the computers in a LAN. Home networks, personal networks and office networks fall in LAN. A typical MAN consists of two or more computers at two different geographical locations in the same city.
A MAN can be wired (fiber optic cable) or wireless and a number of communication devices are used in a MAN. A WAN consists of two or more computers in two different geographical areas (different cities or countries) and there are different methods to connect the computers in a WAN such as leased lines (ISDN lines, radio waves, microwaves, dial-up connections and connectivity through satellite. The internet is a largest WAN in the world. With the invention of the wireless networking, mobile and optical technology the usage of the wires has been decreased. There are a number of the terms that describe the architecture of a network.

Computer Network Topologies
The topology or physical design is closely related to the architecture of a network. Topology defines that how the network is physically connected. There are three main types of the topologies.
• Star Topology: In the star topology the all the networking components are connected to the central point, which is a hub or a switch. The star topology is mostly in use in LAN.
• Bus Topology: In the Bush topology the networking components are connected to the same cable. This is also called linear bus or backbone.
• Ring Topology: In the ring topology the all the components are connected with each other in the form of a ring. A token continuously passes through the loop.

Network Architecture Terminology
• CAN (campus area network): CAN is a type of a network that connects the buildings/offices of a university, educational or office complex.
• Intranet: Intranet is a private network that belongs to an office, college or an organization and that is only accessible to the authorized users.
• Internet: The internet is a network of networks and connecting millions of computes with each other by different designs.
• MAN (metropolitan area network): MAN is a type of a network that is designed for a city. A MAN is larger than LAN but smaller than WAN.
• SAN (storage area network): SAN is a type of a network that is used to connect the storage related devices like RAID, file servers and tape systems.
• VLAN (virtual local area network): VLAN is a type of a network that allows computers on separate physical networks to communicate as if they were connected to the same network.
• Client-Server: Client- Server is a type of networking in which dedicated systems that provides services are called serves and the system that get these services are called work stations. The main services include file, printer, scanner, CD, Hard disk, processor, internet connection and other services.
• Peer-to-peer: This is a type of a networking where each computer shares the same functionalities. No centralized server is required in the Peer to peer networking.

Computer Network Protocols and the OSI Model
Protocol is one of the most important components of a computer network. Protocol means a set of rules, agreed upon ways or a communication language which all computer and devices understand. A protocol defines error checking, how data will be send and receive, and transmitting data between the systems. There are a large number of protocols and following is a list of the most commonly used protocol in the computer communications.
• AppleTalk: AppleTalk is a communication protocol that was developed by the Apple System to connect Macintosh computers to the printers.
• Asynchronous Transfer Mode (ATM): ATM is a type of protocol in which data travels in the form of fixed size packets. These fixed size packets provide high speed, data security, and video and voice communication over the same network.
• DECnet: DECnet is a protocol that was developed by the Digital Equipment Systems to connect the PDP and VAX systems.
• Ethernet: Ethernet is a LAN protocol that was developed by the Intel, Xerox and Digital Equipment System. Ethernet is a most widely used LAN communication standard.
• Fiber Distributed Data Interface (FDDI): FDDI is a protocol that is used to transmit the data over the fiber optic cables.
• Internet Protocols (IP): IP is a protocol transmitting data between the packet switched IP networks originally developed by the DOD (department of defense). TCP/IP (Transmission control protocol/Internet protocol) is a suite of protocol and FTP, HTTP, E-mail, Telnet are all IP protocols.
• Internetwork Packet Exchange (IPX): IPX is a networking protocol that is used by the Novell Netware operating systems.
• NetWare: Netware is a LAN protocol that is developed by the Novell Corporation.
• Signaling System 7 (SS7): SS7 is a telecommunication protocol that was developed by the International Telecommunication Union.
• Systems Network Architecture (SNA): SNA is a set of protocols that was developed by the IBM mainframe systems.
• Token Ring: Token Ring is a LAN protocol that was developed by the IBM where systems have the tokens before they transmit the data. Transmission Control Protocol/Internet Protocol (TCP/IP): TCP/IP is a suite of the protocols used to connect the computers on the internet. TCP/IP is a most commonly used protocol.
• X.25: X.25 is a protocol that was developed by CCITT for the packet switched network.
Protocols are combined with the OSI layers model. OSI model is an ISO standard for the communication system. There are seven layers in the OSI model and each layer performs the different functionalities. The seven layers are Application, Presentation, Session, Transport, Network, Data link and physical layers. Each layer know how to communication with the upper and lower layer. You can remember the name of all the layers by the following sentence.
“All people seems to need data processing”

Planning a Logical Network Design
When you plan a logical network design you can either start from scratch or upgrade an existing network. You should have the sufficient information about the networking components, hardware, protocols and topologies. You should analyze the traffic pattern, security needs, future expansion, and server capability, internet access to the clients, FTP and other things. You should also make a plan for the disaster recovery, data recovery and instant troubleshooting techniques.