Knowt
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
Bus vs star topology
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 faultsBut, 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 |
Operation of a star 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.
Operation of a logical bus network
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 vs logical topology
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 addresses
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
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
Bus vs star topology
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 faultsBut, 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 |
Operation of a star 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.
Operation of a logical bus network
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 vs logical topology
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 addresses
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
