A Star network topology is a network configuration where every device connects directly to a central hub, switch, or router through dedicated point-to-point links. This central device acts as the communication backbone, receiving data from one node and forwarding it to another.
If you've ever plugged a laptop into an office network jack and immediately had internet access, you've used a star topology. That cable ran straight to a switch in a closet somewhere, and that switch was the center of your network universe.This article delivers a no-nonsense breakdown of star topology, how it works, its trade-offs, and practical considerations for design and maintenance. Why does it dominate LANs? Let's dissect it.
Star topology defines a network where every device (PC, server, IoT endpoint, printer etc) connects directly to a central device through dedicated point-to-point links. This central device, which could be a hub, switch, or router, serves as the linchpin for all communication. Unlike a bus topology, where all devices share a single backbone cable, or a ring topology, where data circulates sequentially through each node, star topology isolates each connection.
This isolation eliminates shared collision domains, a key advantage over older designs like bus networks that suffer from contention as traffic increases.
In such a network topology:
The Central Device
The way data moves in a star topology depends heavily on the central device. When a node sends data, it travels over its dedicated link to the central point. If the central device is a hub, it operates at Layer 1 of the OSI model, simply repeating the signal out to all connected ports. This broadcast approach ensures every device receives the data, whether intended or not.
Switches, operating at Layer 2, take a smarter approach: they use Media Access Control (MAC) address tables to learn which devices are on which ports, forwarding frames only to the intended destination (unicast) or, in some cases, to multiple specific ports (multicast).
Routers, functioning at Layer 3, add IP-based routing, making them suitable when the star network connects to external networks, such as in edge deployments.
Cabling
Cabling is typically twisted pair, like Category 5e or 6 for Ethernet up to 1 Gbps over 100 meters, though fiber optic links are common for higher speeds like 10 Gbps or longer distances (OM3 multimode supports 10 Gbps at up to 300 meters; OM4 extends that to 550 meters). Wireless implementations also fit the star model, with Wi-Fi access points acting as the central hub for client devices.
This flexibility in media contrasts sharply with the rigidity of bus topology's coaxial backbone or ring topology's sequential wiring, giving star networks an edge in modern deployments where diverse hardware and protocols (e.g., TCP/IP, Modbus) coexist.
Bandwidth
The total throughput in a star topology is constrained by the central device's capacity. A typical 24-port Gigabit access switch has a 48–56 Gbps backplane—enough for non-blocking, full-duplex traffic across all ports. Exceeding this capacity (e.g., multiple 1 Gbps nodes pushing full duplex on an undersized switch) leads to queuing or dropped packets.
Hubs, limited by their broadcast nature, cap at port speed (e.g., 100 Mbps shared across all nodes), while high-end data center switches (multi-terabit backplanes) support larger, busier networks.
Latency
Switches introduce minimal delay. Cut-through switches forward frames in roughly 2–5 microseconds; store-and-forward switches add more (5–20 µs depending on frame size) since they buffer the entire frame before forwarding. Hubs, however, increase latency by broadcasting to all ports, forcing nodes to process irrelevant traffic, which can add milliseconds under load (e.g., 1–3 ms in a 10-node 100 Mbps network).
Link quality and cable length (e.g., 100m Cat6 limit) also factor in, though propagation delay is negligible at LAN scales.
Fault Tolerance
A single cable failure isolates only the affected node, leaving others operational e.g., a cut Cat6 link to a PC doesn't disrupt the switch or other devices. However, the central device is a critical vulnerability: a switch crash or power loss disables all communication.
This trade-off demands robust hardware or redundancy for mission-critical setups.
Scalability
Growth is straightforward up to the central device's port capacity for instance a 24-port switch supports 24 nodes, expandable to 48 with a dual-stack setup. Beyond that, cascading switches via high-speed uplinks (e.g., 10 Gbps SFP+) extends the network, though each hop adds slight latency and complexity.
This linear scaling beats bus topology's contention limits but caps at practical port counts (e.g., 96–128 nodes before core upgrades).
In enterprise environments, star topology is typically implemented as part of a hierarchical network design that optimizes both performance and manageability.
The three-tier architecture in networking consists of:
In a simplified implementation, especially for small to mid-sized enterprises, the distribution layer may be omitted, creating a two-tier network with a direct star topology between core and access switches.
A typical configuration for a core switch in a star topology:
interface Port-channel1 switchport mode trunk switchport trunk allowed vlan 10,20,30 switchport trunk native vlan 99 ! interface GigabitEthernet1/1 switchport mode trunk switchport trunk allowed vlan 10,20,30 channel-group 1 mode active ! interface GigabitEthernet1/2 switchport mode trunk switchport trunk allowed vlan 10,20,30 channel-group 1 mode active
This configuration creates an EtherChannel bundle using LACP (Link Aggregation Control Protocol) for redundancy and load balancing between the core and access switches, while also configuring VLAN trunking for efficient traffic management. Note: spanning-tree portfast trunk was removed from this config—portfast should never be used on switch-to-switch trunk links, only on access ports connecting end devices.
A big win for star topology is how it isolates problems. Each device has its own connection to the hub, so if one connection goes down, it doesn't affect the others. Engineers can quickly check switch port LEDs (e.g., green for active, amber for errors) or pull port statistics via CLI (e.g., show interface on a Cisco switch) to pinpoint a dead link or overloaded node.
Adding nodes is as simple as connecting a cable to an available switch port or patch panel, requiring no network-wide reconfiguration. For example, deploying a new workstation in an office involves plugging in a Cat6 cable and verifying link status and can be done in minutes. This plug-and-play nature reduces downtime and labor compared to rewiring a bus or reconfiguring a ring.
Since all data traffic goes through the central hub, IT teams can monitor, analyze, and fix network performance in real-time.
Unlike bus topology, where everything shares the same channel, star topology gives each device its own dedicated path. This avoids those annoying collisions, ensuring faster, more reliable data transmission.
Managed switches support Virtual LANs (VLANs) to segment traffic (e.g., separating guest Wi-Fi from corporate data), Access Control Lists (ACLs) to block unauthorized IPs, and Simple Network Management Protocol (SNMP) for real-time monitoring. For instance, an IT team can lock down a port to a specific MAC address, thwarting rogue devices.
The star topology supports a wide range of media and protocols, from 10 Mbps Ethernet over Cat5 to 10 Gbps over fiber, and even wireless via Wi-Fi access points. It handles TCP/IP for office LANs, Modbus for industrial control, or VoIP for call centers. Engineers can swap media (e.g., fiber for distance) without altering the core design.
The central device's criticality is a major drawback. If a switch loses power or its firmware crashes the entire network goes dark. A 48-node office LAN could halt operations, costing hours of downtime. Mitigation requires redundancy, like dual switches with failover via Spanning Tree Protocol (STP) or a hot-spare hub, but this adds cost and complexity.
Radial wiring drives up expenses for instance e.g., 10 nodes at 50m each need 500m of Cat6 (~$150–$250 at $0.30–$0.50/m), versus 50m (~$15–$25) for a bus backbone. Add switch costs (e.g., $300 for a 24-port Gigabit model) and labor for running cables through ceilings or conduits, and star topology outpaces simpler designs. Large deployments (e.g., a 100-node campus) amplify this gap significantly.
Performance is dependent on the central device. Hubs broadcast all traffic, choking at 100 Mbps with just a few active nodes (e.g., 10 PCs streaming video). Even switches falter if underpowered. A $100 switch with a 5 Gbps backplane buckles under 10 nodes at 1 Gbps each, dropping packets. Engineers must spec hardware to match their port count—a 24-port Gigabit switch needs at least a 48 Gbps backplane for non-blocking performance.
The central device demands physical infrastructure (eg a 48-port switch needs 1U rack space), active cooling (fans pulling 50W), and a UPS for outages (e.g., 500VA unit at $150). In tight server rooms or remote sites, this footprint complicates deployment. Power draw also rises with PoE (e.g., 720W for 24 ports at 30W each), straining electrical budgets.
Read more: Modern networks often combine these topologies into hybrid network designs that leverage each approach's strengths while minimizing weaknesses.
Physical and logical star topology describe two different layers of the same network, and mixing them up causes real confusion when troubleshooting or designing.
Physical star topology refers to how cables are physically arranged. Every device has its own cable running back to a central switch or hub. If you walked into the server room and traced the wires, you'd see the star pattern—individual runs fanning out from a central patch panel.
Logical star topology refers to how data actually flows. This is where it gets interesting, because the physical layout doesn't always match the logical behavior:
This distinction matters in practice. If you're troubleshooting broadcast storms on a hub-based star network, you need to think in bus topology terms—every device receives every frame. On a switched star, broadcast traffic is limited to the VLAN, and unicast stays between two ports.
Most modern networks are physical and logical stars, since hubs are effectively extinct. But the concept still shows up on certification exams (CCNA, CompTIA Network+) and in legacy environments where older hubs remain in service.
An extended star topology connects multiple simple star networks together by linking their central switches through a higher-level switch or backbone. Instead of one switch serving all devices, you have a hierarchy: access switches in each area connect their local devices, and those access switches connect upward to a core or distribution switch.
Think of a multi-floor office building. Each floor has its own 24-port access switch serving that floor's workstations, phones, and printers. All those floor switches connect via uplinks to a core switch in the main data closet. The result is a star of stars—each floor is a star, and the inter-floor connections form another star at a higher level.
Extended star vs. daisy-chaining:
Daisy-chaining switches in series (Switch A → Switch B → Switch C) creates sequential dependencies—if Switch B fails, Switch C loses connectivity too. Extended star avoids this by connecting every access switch directly back to the core. Each spoke is independent, so a single access switch failure only affects that floor or department.
When to use extended star:
Extended star is essentially what enterprise networks call a two-tier or three-tier architecture. It scales far better than a flat single-switch design, and it's the standard approach once you outgrow 48 ports. For a broader look at how star combines with other designs, see hybrid network topology.
Large enterprises leverage star topology for its stability and scalability. Multi-floor offices deploy a 24-port Gigabit switch per department, uplinked to a core switch with a 100 Gbps backplane for inter-floor traffic.
VLANs segment departments (e.g., HR vs. engineering) to allocate bandwidth, while MPLS or metro Ethernet variants connect remote offices to provider edge (PE) routers, ensuring secure cloud service access for multinational firms.
Universities and schools use star topology to centralize data across classrooms and research labs. A campus LAN might feature a 48-port switch in a data closet, serving student PCs, faculty servers, and Wi-Fi APs enabling seamless access to online libraries and learning platforms.
Scalability supports adding new labs without rewiring.
Hospitals depend on star topology for reliable, secure connectivity. A 24-port PoE switch links patient monitors, MRI scanners, and EHR workstations, with QoS prioritizing real-time data (e.g., heart rates over file transfers). Redundant switches in critical care units ensure uptime, vital for life-saving equipment.
Data centers use star topology to manage thousands of VMs and storage arrays. A top-of-rack (ToR) switch (e.g., 48-port 10GbE) connects servers in a rack to a 100 Gbps core switch, delivering low-latency access to cloud resources. Fault tolerance keeps VMs online during link failures.
Smart homes rely on star topology via a central router (e.g., Wi-Fi 6 hub) connecting Alexa devices, smart thermostats, and cameras. While mesh networks like Google Nest Wi-Fi offer robustness for dense IoT setups, star remains simpler for smaller homes, with all traffic routed through the hub to cloud servers.
Learn more about Mesh topology.
Star topology costs more upfront than bus or ring designs, but the total cost of ownership usually works in its favor once you factor in reliability, troubleshooting time, and scalability. Here's what a realistic budget looks like.
| Component | Small Office (8–24 nodes) | Mid-Size (48–96 nodes) | Enterprise (200+ nodes) |
|---|---|---|---|
| Access switch(es) | $300–$500 (24-port GigE) | $800–$2,000 (2x 48-port) | $5,000–$15,000+ (multiple managed) |
| Core/distribution switch | Not needed | $1,500–$4,000 | $8,000–$25,000+ |
| UPS backup | $150–$300 | $300–$800 | $1,500–$5,000 |
| SFP+ transceivers | Not needed | $50–$150 each | $100–$400 each |
Cable runs are where star topology's radial design adds up. Each device needs its own home run back to the switch:
For 24 devices averaging 30-meter cable runs, expect roughly $250–$450 in cable alone, plus $200–$500 for installation labor.
| Cost Factor | Star | Bus | Ring |
|---|---|---|---|
| Initial cabling | Higher (individual runs) | Lowest (shared backbone) | Moderate (sequential loop) |
| Switch/hub hardware | $300–$25,000+ | $0–$50 (terminators only) | $500–$5,000 (managed ring switches) |
| Adding 10 devices | Low ($50–$150 cable + ports) | Very low ($20–$50 cable) | Moderate (must break and re-close ring) |
| Troubleshooting labor | Low (centralized) | High (no diagnostics) | High (sequential tracing) |
| Downtime cost/year | Low (isolated failures) | High (single cable kills network) | Moderate to high |
| 5-year TCO (24 nodes) | $1,500–$4,000 | $500–$1,500 | $2,000–$5,000 |
The upfront gap narrows fast. A single bus topology outage that takes down 24 users for half a day can cost more in lost productivity than the price difference in hardware.
Practice building and costing out star topology designs in CloudMyLab's hosted GNS3 environments—test configurations on virtual topologies before committing budget to production hardware.
Choosing the right topology depends on your environment. Here's how star stacks up against every major alternative:
| Feature | Star | Bus | Ring | Mesh | Hybrid |
|---|---|---|---|---|---|
| Fault Tolerance | Central switch is single point of failure | Single cable break kills network | Poor (single ring); Good (dual ring) | Excellent—multiple redundant paths | Flexible by design |
| Scalability | Excellent—add ports or cascade switches | Limited (~30 per segment) | Moderate | Poor for full mesh | Unlimited |
| Cost | Low–Moderate | Lowest | Moderate | Highest | Moderate–High |
| Performance | Dedicated bandwidth per port | Shared, collision-prone | Predictable latency | Best (parallel paths) | Varies by segment |
| Troubleshooting | Easy (centralized) | Difficult (no diagnostics) | Complex (sequential) | Moderate | Complex |
| Best For | Office LANs, campuses | Legacy/industrial only | Telecom, industrial rings | Data center cores | Enterprise backbone |
For a broader overview of all network designs, see what is network topology.
Test cable continuity with a Fluke tester (e.g., for signal loss over 100m Cat6), check switch port logs for errors (e.g., CRC failures), or monitor link LEDs. Use ping or traceroute to confirm packet loss e.g., >2% loss signals a failing link. CloudMyLab offers virtual lab environments to simulate these failures, letting engineers practice diagnostics on Cisco switches without risking live networks.
Segment traffic with VLANs to reduce broadcast storms; upgrade uplinks to 10 Gbps if utilization hits >70% (check via switch GUI). Adjust QoS for latency-sensitive apps like VoIP (e.g., prioritize DSCP EF traffic). CloudMyLab's cloud-based labs help test tuning configs on virtual topologies before deployment.
For core-access star implementations, consider these additional optimizations:
show etherchannel summary on Cisco devicesUpdate switch firmware quarterly to patch bugs (e.g., via vendor portals like Cisco's); test cables annually with a TDR for degradation (e.g., shorts from wear). Clean dust from switch fans to prevent overheating.
Implementing a star topology between core and access switches ensures a robust, scalable, and efficient network design. With proper redundancy, VLAN segmentation, and routing considerations, a star topology forms the foundation of a well-structured enterprise network.
You may dive deeper into topology articles like hybrid topology to master their nuances and trade-offs. For hands-on learning, CloudMyLab offers hosted network simulation with tools like GNS3, EVE-NG, and Cisco Modeling Labs (CML). These cloud-based labs let you build, test, and refine star topologies virtually, including testing CCNA-level protocols like LACP, PAgP, and RSTP. If you are working on your certification prep, a design validation, or troubleshooting practice, you can practice configurations for EtherChannel, VLAN trunking, and spanning tree optimization, all without hardware overhead.
Star topology is a network layout where every device (computer, printer, server) connects directly to one central switch or hub. All communication between devices passes through that central point. If one device's cable fails, only that device is affected, everything else keeps working.
Both. In wired networks, devices connect via Ethernet cables to a central switch. In wireless networks, devices connect via Wi-Fi to a central access point. Either way, it's the same star pattern, all traffic flows through one central device.
For standard Ethernet over Cat5e or Cat6 cable, the maximum distance from the switch to any device is 100 meters (328 feet). Fiber optic connections extend this: OM3 multimode reaches 300 meters for 10GbE, OM4 reaches 550 meters, and single-mode fiber goes up to 10 kilometers depending on the transceiver.
Yes. Managed switches support Quality of Service (QoS) settings that prioritize voice and video traffic over regular data. PoE switches can also power IP phones directly through the Ethernet cable, eliminating the need for separate power adapters at each desk.
All communication stops. Every connected device loses network access because all traffic must pass through the central switch. To prevent this, production networks use redundant switches with Spanning Tree Protocol failover, HSRP/VRRP for gateway redundancy, and UPS power backup.
Star topology dominates because it offers the best balance of reliability, manageability, and cost. Individual failures are isolated, adding devices requires no downtime, and all modern networking equipment (switches, structured cabling, patch panels) is built for star wiring. The TIA-568 standard specifies star topology for commercial buildings.