A computer network is a system of interconnected computers and peripheral devices
For example, it may connect computers, printers, External Hard Drives and cameras
How are networks classified?
Topology : The geometric arrangement of devices on the network. For example, devices can be arranged in a ring or in a straight line.
protocols : The rules and encoding specifications for sending data. The protocols also determine whether the network uses a peer-to-peer or client/server architecture.
media : Devices can be connected by twisted-pair wire, coaxial cables, or fiber optic cables. Some networks do without connecting media altogether, communicating instead via radio waves.
What are the different types of networks?
LAN (Local Area Network)
MAN (Metropolitan Area Network)
Local Area Network
Smallest network compared to the others
The simplest form of LAN is to connect two computers together
LAN is operated within a limited physical area, such as School or Home
Metropolitan Area Network
“ Metropolitan” – describes important cities such as Sydney, Singapore, Hong Kong, Tokyo and London
Companies that have several branches within a city such as banks, use a MAN
Often acts as a high speed network ( although not as fast as LAN) to allow sharing of regional resources
Comparison of LAN, MAN Large Small Number of computers Twisted-pair and fibre-optics cable Twisted-pair Transmission media type Slow Fast Speed Large Small Network Size High Low Cost MAN LAN Criteria
The shape of a local-area network (LAN) or other communications system
All devices are connected to a central cable, called the bus or backbone. Bus networks are relatively inexpensive and easy to install for small networks. Ethernet systems use a bus topology
All devices are connected to one another in the shape of a closed loop, so that each device is connected directly to two other devices, one on either side of it. Ring topologies are relatively expensive and difficult to install, but they offer high bandwidth and can span large distances.
All devices are connected to a central hub. Star networks are relatively easy to install and manage, but bottlenecks can occur because all data must pass through the hub.
Basic Hardware Components
Network interface card
Network interface card
Often abbreviated as NIC, an expansion board you insert into a computer so the computer can be connected to a network. Most NICs are designed for a particular type of network, protocol, and media, although some can serve multiple networks.
A network switch is a small hardware device that joins multiple computers together within one local area network (LAN)
A switch stores the MAC Address of every device which is connected to it.
MAC addresses are globally unique addressed that are written into hardware at the time of manufacture
A MAC address is 48 bits long. This means that there are 281,474,976,710,656 possible MAC addresses
If the switch does not recognize the MAC Address, it will not know which port to copy the frame to. When that happens, the switch will broadcast the frame to all of its ports.
A common connection point for devices in a network. Hubs are commonly used to connect segments of a LAN. A hub contains multiple ports. When a packet arrives at one port, it is copied to the other ports so that all segments of the LAN can see all packets.
A network device that forwards packets from one network to another. . Based on internal routing tables, routers read each incoming packet and decide how to forward it. The destination address in the packets determines which interface on the router outgoing packets are directed to