STATE AND EXPLAIN
💡 The Star topology description of a network can also include or imply the nature of the data flow through the network. And practical term used in professional training.
This topology branches each network device off a central device called a Switch or Hub, making it very easy to add a new workstation. Also, if any workstation goes down it does not affect the entire network. (But, as you might expect, if the central device goes down, the entire network goes down). Some types of Ethernet and ARCNet use a physical star topology. Figure 8.7 gives an example of the organization of the star network. Star topologies are easy to install. A cable is run from each workstation to the Switch or Hub. The Switch or Hub is placed in a central location in the office. Star topology are more expensive to install than bus networks, because there are several more cables that need to be installed, plus the cost of the Switch or Hubs that are needed.
FAQ Execution
Star topology is a network structure where all devices connect to a central device such as a switch or hub.
Ethernet UTP cable (Cat5e, Cat6, Cat6A).
Modern Ethernet networks like 100BASE-T and 1000BASE-T.
Star topology should be used when:
I) Centralized network management is required.
II) Easy troubleshooting is needed.
III) Medium or large office networks exist.
IV) High reliability is required.
V) Ethernet switching environment is used.
Enterprise LAN, Data centers, Schools and universities, Smart city command centers, Corporate offices
When: Cabling budget is extremely limited, Infrastructure requires no central device, Remote distributed locations
Advantage : Failure of one device does not affect other devices.
Disadvantage : If the central switch fails, the whole network stops.
Advantage: Low cost and simple installation.
Disadvantage: If backbone fails, entire network fails.
The Network Switch.
When multiple switches connect to the core switch.
Straight-through Ethernet cable.
100 meters per link.
Because each device has a dedicated communication link.
Each device receives dedicated bandwidth from the switch.
Ethernet switching and MAC address table forwarding.
Use : Dual switches, Link aggregation, Redundant uplinks
When uplink bandwidth is less than total access bandwidth. It means all devices cannot transmit at full speed simultaneously.
Suppose: 48 cameras and Each camera = 8 Mbps
Total traffic: 48×8Mbps=384Mbps (If uplink = 1Gbps, then)
Total traffic: 384Mbps less than 1000Mbps (So no congestion occurs.)
Requiirement : Install central switch, Run Ethernet cables to each device, Terminate cables using RJ45 connectors, Connect devices to switch ports, Configure IP addressing, Wiring standard should be T568A & T568B
It organizes network cables in structured cabling systems.
Loose cable, Faulty switch port, IP conflict
Spine-Leaf architecture.
Combination of : Star + mesh & Star + tree
Because centralized switches manage CCTV, sensors, and network devices.
Small IoT networks, Industrial communication and Temporary network setups
| Network Type | Oversubscription |
|---|---|
| Small LAN | 1:1 |
| Enterprise Access Layer | 4:1 |
| Campus Network | 8:1 |
| Data Center | 1:1 or 3.1 |
| CCTV Network | 20.1 |
Cable Calculation Formula = 'Sum of distance from each device to the central switch
Total Meters in Cable: PC1 = 10 m + PC2 = 15 m + PC3 = 8 m + PC4 = 12 m
=> 10 + 15 + 8 + 12 = 45 Meters
Switch Ports Required = Number of Devices + Uplink Ports
Where: Devices = 20 & plink ports = 2
=> 22 Ports
Formula for calculating cable requirement :
'Total Cable = Distance between nodes × (Number of Nodes – 1)'
If Distance between nodes = 5 meters
Number of nodes = 10
Total Cable = 5 × (10 – 1)
Total Cable = 45 meters
Formula : Oversubscription = Access Bandwidth / Uplink Bandwidth
Where:
Access Bandwidth = Number of Access Ports × Port Speed
Uplink Bandwidth = Number of Uplink Ports × Uplink Speed
Oversubscription = (Number of Access Ports × Port Speed) / (Number of Uplink Ports × Uplink Speed)
Oversubscription = 24 × 1Gbps / 2 × 10Gbps
Oversubscription = 24Gbps / 20Gbps => 1.2:1
