STATE & FAQ ON TOPOLOGYThis 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.
💡 Star 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.
# INTERVIEW PREP GUIDE ABOUT STAR NETWORK TOPOLOGY (PHYSICAL & LOGICAL)
🔹 What is Star Topology in computer networking ?
Star topology is a network structure where all devices connect to a central device such as a switch or hub.
🔹 Which cable type is commonly used in star topology ?
Ethernet UTP cable (Cat5e, Cat6, Cat6A).
🔹 Which network standard mainly uses star topology ?
Modern Ethernet networks like 100BASE-T and 1000BASE-T.
🔹 How do we know Star Topology should be applied in network infrastructure ?
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.
🔹 In which environments is star topology commonly used ?
Enterprise LAN, Data centers, Schools and universities, Smart city command centers, Corporate offices
🔹 When should Star Topology not be used ?
When: Cabling budget is extremely limited, Infrastructure requires no central device, Remote distributed locations
🔹 What is the biggest advantage and disadvantage of Star Topology ?
Advantage : Failure of one device does not affect other devices.
Disadvantage : If the central switch fails, the whole network stops.
🔹 What is the advantage & disadvantage of bus topology ?
Advantage: Low cost and simple installation.
Disadvantage: If backbone fails, entire network fails.
🔹 What device acts as the heart of star topology ?
The Network Switch.
🔹 What is extended star topology ?
When multiple switches connect to the core switch.
🔹 What type of cable is used between switch and devices ?
Straight-through Ethernet cable.
🔹 What is maximum Ethernet cable distance in star topology ?
100 meters per link.
🔹 Why does star topology provide better performance than bus topology ?
Because each device has a dedicated communication link.
🔹 How does bandwidth work in star topology ?
Each device receives dedicated bandwidth from the switch.
🔹 What protocol manages traffic in Ethernet star networks ?
Ethernet switching and MAC address table forwarding.
🔹 How to design redundancy in star topology ?
Use : Dual switches, Link aggregation, Redundant uplinks
🔹 What is oversubscription in star topology ?
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.)
🔹 What are the steps to install star topology ?
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
🔹 What is the role of patch panel in star topology ?
It organizes network cables in structured cabling systems.
🔹 What is the most common issue in star topology networks ?
Loose cable, Faulty switch port, IP conflict
🔹 What topology is used in modern data centers instead of simple star ?
Spine-Leaf architecture.
🔹 What is hybrid star topology ?
Combination of : Star + mesh & Star + tree
🔹 Why is star topology useful in smart city control rooms ?
Because centralized switches manage CCTV, sensors, and network devices.
🔹 Where can Bus Topology still be useful today ?
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 |
🔹 Star Topology Formula ?
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
🔹 How to find the Oversubscription Ratio from start topology ?
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
