Network topology

Local area networks

Local Area Network (LAN): A number of computing devices on a single site or in a single building, connected together by cables
May consist of a number of PCs, other devices (like printers and scanners), and a central server.
Users on the network can:
- Communicate with each other
- Share data
- Share hardware devices (e.g. printers and scanners)
Can transmit data very fast, but only over a short distance

LANs can use different layouts, or topologies
Network topology: The arrangement of the elements of a communication network

Bus topology	Star topology
All computers connected to a single cable, the ends of which are plugged into a terminator	All computers connected to a central node, which may be a switch or computer acting as a router to transmit messages
}}Inexpensive to install - requires less cable and no additional hardware}}	[[Costly to install - a lot more cable required[[
[[If the main cable fails, network data can no longer be transmitted to any of the nodes[[	}}If one cable fails, only one station is affected - simple to isolate faults}}[[But, if the central device fails, network data can no longer be transmitted to any node[[
[[Performance degrades with heavy traffic[[	}}Consistent performance even when the network is being heavily used}}
}}Low security - all computers on the network can see all data transmissions}}	}}System is more secure - messages sent directly to the central computer and cannot be intercepted by other stations}}
	}}No problems with data ‘collisions’}}
	}}Higher transmission speeds - can give better performance}}
	}}Easy to add stations without disrupting the network}}

Switch keeps a record of the unique MAC address of each device on the network and can identify which particular computer on the network it should send the data to.

Network signals are sent through the main cable to reach all connected devices (or station)
Traffic generated by each station has equal priority
Each message contains a destination address that identifies its intended recipient
Only the intended recipient actually accepts and processes the message

Physical topology: The actual design layout of a network
Logical topology: The shape of the path the data travels in a network, describing how components communicate across the physical topology
They are independent of each other
- A network physically wired as a star topology can behave logically as a bus network by using a bus protocol and appropriate physical switching
- Any variety of Ethernet uses a logical bus topology when components communicate, regardless of the physical cable layout

MAC address: Media Access Control address
Media Access Control (MAC) address: The unique address that identifies a NIC, which is assigned and hard-coded by the manufacturer
48 bits long
Written as 12 hex digits
- E.g. 00-09-5D-E3-F7-62
Unique → can be used to track devices