Computer Network Management

Internetworking is connecting two or more distinct computer networks or the network segments via a common routing technology. The result is an internetwork often called internet.

Any interconnection among or between public,private, commercial, industrial, or governmental networks may also be defined as an internetwork.

In modern practice there are three variants of internetwork, depending on who administers and who participates in them:

* Intranet

* Extranet

* Internet

Intranets and extranets may or may not have connections to the Internet. If connected to the Internet, the intranet or extranet is normally protected from being accessed from the Internet without proper authorization.

# The Intranet

An intranet is a set of networks, using the Internet Protocol and IP-based tools such as web browsers and file transfer applications, that is under the control of a single administrative entity. That administrative entity closes the intranet to all but specific, authorized users.

Most commonly, an intranet is the internal network of an organization. A large intranet will typically have at least one web server to provide users with organizational information.

# The Extranet

An extranet is a network or internetwork that is limited in scope to a single organization or entity but which also has limited connections to the networks of one or more other usually, but not necessarily, trusted organizations or entities.

Technically, an extranet may also be categorized as a CAN, MAN, WAN, or other type of network, although, by definition, an extranet cannot consist of a single LAN; it must have at least one connection with an external network.

# The Internet

The Internet is a specific internetwork. It consists of a worldwide interconnection of governmental, academic, public, and private networks based upon the networking technologies of the Internet Protocol Suite.

It is the successor of the Advanced Research Projects Agency Network (ARPANET) developed by DARPA of the U.S. Department of Defense.

The Internet is also the communications backbone underlying the World Wide Web (WWW).

# Node : A physical network node is an active electronic device that is attached to a computer network which is capable of sending, receiving, or forwarding information over the communication channel.

In data communication, a physical network node may either be a modem,hub,bridge,switch; or a digital telephone handset, a printer or a host computer.

# Bridges : A network bridge connects multiple network segments at the data link layer of the OSI model. Bridges do not exactly copy traffic to all ports, as hubs do, but learn which MAC addresses are reachable through specific ports. Once the bridge associates a port and an address, it will send traffic for that address only to that port.

# Switches : A networking switch is the central device in a wired or wireless LAN .It receives signals from each computer on the network via Ethernet cables in a wired network or radio waves in a wireless LAN. In both cases, the networking switch directs traffic across the LAN, enabling the computers to communicate and share resources.

This is distinct from a hub in that it only forwards the packets to the ports involved in the communications rather than all ports connected.

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Depending on their scope, the types of computer networks are :

1. Personal area network(PAN)

It is a computer network used for communication among computer devices close to one person.

Some of the devices that are used in a PAN are printers, fax machines, telephones, PDAs and scanners. The reach of a PAN is typically about 20-30 feet which can also be increased with technology improvements.

2. Local area network(LAN)

It is a computer network covering a small physical area, like a home, office, or small group of buildings, such as a school, or an airport.

The defining characteristics of LANs, in contrast to WANs (wide area networks), include their higher data transfer rates, smaller geographic range, and lack of a need for leased telecommunication lines.

Also multiple LANs can be interconnected to increase the scope of the network.

3. Campus area network(CAN)

It is a computer network made up of an interconnection of local area networks (LANs) within a limited geographical area.

It can be considered one form of a metropolitan area network, specific to an academic setting.

A campus area network is larger than a local area network but smaller than a wide area network (WAN) (in some cases).

The main aim of a campus area network is to facilitate students accessing internet and university resources. This is a network that connects two or more LANs but that is limited to a specific and contiguous geographical area such as a college campus, industrial complex, office building, or a military base.

4. Metropolitan area network(MAN)

Its a network that connects two or more local area networks or campus area networks together but does not extend beyond the boundaries of the immediate town/city.

Routers, switches and hubs are connected to create a metropolitan area network.

5. Wide area network(WAN)

Its a computer network that covers a broader area. Less formally, a WAN is a network that uses routers and public communications links Contrast with PANs,LANs,CANs or MANs which are usually limited to a room, building, campus or specific metropolitan area respectively.

The largest and most well-known example of a WAN is the Internet. A WAN is a data communications network that covers a relatively broad geographic area i.e. one city to another and one country to another country.

6. Global area network(GAN)

A global area networks specification is in development by several groups which is a model for supporting mobile communications across an arbitrary number of wireless LANs, satellite coverage areas and so on.

7. Virtual private network(VPN)

It is a computer network in which some of the links between nodes are carried by open connections or virtual circuits in some larger network instead of by physical wires.

One common application is secure communications through the public Internet.

A VPN allows computer users to appear to be editing from an IP address location other than the one which connects the actual computer to the Internet.

8. Internetwork

Internetworking involves connecting two or more distinct computer networks or network segments via a common routing technology. The result is called an internetwork often shortened to internet.

In modern practice, the interconnected networks use the Internet Protocol. There are at least three variants of internetwork, depending on who administers and who participates in them:

* Intranet

* Extranet

* Internet

Depending on their scope, the types of computer networks are :

1. Personal area network(PAN)

It is a computer network used for communication among computer devices close to one person.Some of the devices that are used in a PAN are printers, fax machines, telephones, PDAs and scanners. The reach of a PAN is typically about 20-30 feet which can also be increased with technology improvements.

2. Local area network(LAN)

It is a computer network covering a small physical area, like a home, office, or small group of buildings, such as a school, or an airport.The defining characteristics of LANs, in contrast to WANs (wide area networks), include their higher data transfer rates, smaller geographic range, and lack of a need for leased telecommunication lines.Also multiple LANs can be interconnected to increase the scope of the network.

3. Campus area network(CAN)

It is a computer network made up of an interconnection of local area networks (LANs) within a limited geographical area.It can be considered one form of a metropolitan area network, specific to an academic setting.A campus area network is larger than a local area network but smaller than a wide area network (WAN) (in some cases).The main aim of a campus area network is to facilitate students accessing internet and university resources. This is a network that connects two or more LANs but that is limited to a specific and contiguous geographical area such as a college campus, industrial complex, office building, or a military base.

4. Metropolitan area network(MAN)

Its a network that connects two or more local area networks or campus area networks together but does not extend beyond the boundaries of the immediate town/city.Routers, switches and hubs are connected to create a metropolitan area network.

5. Wide area network(WAN)

Its a computer network that covers a broader area. Less formally, a WAN is a network that uses routers and public communications links Contrast with PANs,LANs,CANs or MANs which are usually limited to a room, building, campus or specific metropolitan area respectively.The largest and most well-known example of a WAN is the Internet. A WAN is a data communications network that covers a relatively broad geographic area i.e. one city to another and one country to another country.

6. Global area network(GAN)

A global area networks specification is in development by several groups which is a model for supporting mobile communications across an arbitrary number of wireless LANs, satellite coverage areas and so on.

7. Virtual private network(VPN)

It is a computer network in which some of the links between nodes are carried by open connections or virtual circuits in some larger network instead of by physical wires.One common application is secure communications through the public Internet.A VPN allows computer users to appear to be editing from an IP address location other than the one which connects the actual computer to the Internet.

8. Internetwork

Internetworking involves connecting two or more distinct computer networks or network segments via a common routing technology. The result is called an internetwork often shortened to internet.In modern practice, the interconnected networks use the Internet Protocol. There are at least three variants of internetwork, depending on who administers and who participates in them:

* Intranet

* Extranet

* Internet

Computer Networks can be classified depending upon the following criterion:

1. The Connection method

Networks can be classified according to the hardware and software technology that is used to interconnect the individual devices in the network, such as Optical fiber, Ethernet, Wireless LAN, Home PNA.

2. Network Scope

Networks are often classified as Local Area Network (LAN), Wide Area Network (WAN), Metropolitan Area Network (MAN), Personal Area Network (PAN), Virtual Private Network (VPN), Campus Area Network (CAN), Storage Area Network (SAN), etc. depending on their scale, scope and purpose.

3. Functional relationship i.e network architecture

Networks may be also be classified according to the functional relationships which exist among the elements of the network, e.g. Active Networking, Client-server and Peer-to-peer (workgroup) architecture.

4. Network topology

Computer networks may also be classified according to the network topology upon which the network is based, such as bus network, star network, ring network, mesh network, star-bus network, tree or hierarchical topology network.

Network topology relates to the way in which devices in the network are and their logical relations to one another. The use of the term "logical" here is significant. That is, network topology is independent of the "physical" layout of the network.

5. Lastly depending upon the method of data communication networks can be classified as Digital and Analog networks.