What is Internet Speed? Detail Explained
Internet speed is an important factor in today’s digital world. It determines how quickly we can access websites,…
A hub broadcasts every frame to all connected ports (Layer 1, no intelligence). A switch forwards frames only to the correct port using MAC addresses (Layer 2). A router routes packets between different networks using IP addresses (Layer 3). Hubs are obsolete — modern networks use switches and routers.
Key takeaways
- Hub = Layer 1 — no intelligence, broadcasts to all ports, creates one collision domain, completely obsolete
- Switch = Layer 2 — uses MAC address table, one collision domain per port, full-duplex, widely used in LANs
- Router = Layer 3 — uses IP routing table, separates broadcast domains, connects different networks
- Home routers are 3-in-1 devices: router + switch (LAN ports) + wireless access point
- Layer 3 switches can route between VLANs without a separate router — used at distribution/core layer
- Switches flood unknown unicast frames to all ports — this is not a security risk in normal operation
- Default gateway = the router's IP address that devices send traffic to when destination is outside local network
A hub broadcasts data to all connected devices (Layer 1). A switch forwards frames only to the correct device using MAC addresses (Layer 2). A router routes packets between different networks using IP addresses (Layer 3). In modern networks, hubs are obsolete — switches and routers do all the work.
Quick Comparison Table
| Feature | Hub | Switch | Router |
|---|---|---|---|
| OSI Layer | Layer 1 (Physical) | Layer 2 (Data Link) | Layer 3 (Network) |
| Addressing | None | MAC address | IP address |
| Forwarding | Broadcast to all ports | Unicast to specific port | Routes between networks |
| Collision domain | One (shared) | One per port | One per port |
| Broadcast domain | One | One (per VLAN) | One per interface |
| Intelligence | None | MAC address table | Routing table |
| Used in? | Obsolete | LANs everywhere | Between networks, internet |
| Speed | Half-duplex only | Full-duplex | Full-duplex |
What is a Hub?
A hub is the simplest network device — it has no intelligence. Every frame received on any port is immediately retransmitted out every other port. It operates at OSI Layer 1 and has no awareness of MAC addresses or IP addresses.
Problems with hubs:
- Collisions: All ports share a single collision domain — only one device can transmit at a time
- Security risk: Every device sees every frame — trivial to sniff traffic with a packet analyzer
- Bandwidth waste: A 100 Mbps hub shared among 8 devices = ~12.5 Mbps average per device
Status: Hubs are completely obsolete. They have not been manufactured for mainstream use since the early 2000s. Every modern network uses switches.
What is a Switch?
A network switch is an intelligent Layer 2 device. When a frame arrives, the switch reads the source MAC address, records which port it came from, and stores this in its MAC address table (also called CAM table). When forwarding, the switch sends the frame only to the port associated with the destination MAC address — not to every port like a hub.
How a Switch Forwards Frames
- Frame arrives on port 1 from Device A (MAC: AA:AA:AA:AA:AA:AA)
- Switch records: Port 1 = AA:AA:AA:AA:AA:AA in MAC table
- Switch reads destination MAC: BB:BB:BB:BB:BB:BB
- If BB:BB:BB:BB:BB:BB is in the table on port 3 → sends frame ONLY to port 3
- If not in table → floods frame to all ports (unknown unicast flood)
Switch Benefits
- Dedicated bandwidth: Each port = its own collision domain — full-duplex, no collisions
- Security: Devices only receive frames addressed to them
- VLANs: Logical network segmentation within one physical switch
- Speed: Modern switches operate at 1 Gbps, 10 Gbps, 25 Gbps, or 100 Gbps per port
Types of Switches
- Unmanaged: Plug and play, no configuration — home/small office use
- Managed: VLAN support, STP, port security, monitoring — enterprise use
- Layer 3 switch: Has built-in routing capability — routes between VLANs without a separate router
- PoE switch: Powers IP phones, cameras, and WAPs through the Ethernet cable
What is a Router?
A router operates at Layer 3 and connects different networks together. While a switch works with MAC addresses within the same network, a router works with IP addresses and makes decisions about where to send packets across different networks.
Your home router connects your local network (192.168.x.x) to the internet (your ISP’s network). Without it, your devices could only communicate with each other — not with the wider internet.
What a Router Does
- Receives a packet, reads the destination IP address
- Looks up the destination in its routing table
- Forwards the packet out the appropriate interface toward the destination
- Strips the old Layer 2 header and writes a new one for the next hop
- Decrements the TTL (Time to Live) — drops packet if TTL reaches 0
Router Features
- NAT: Translates private IPs to public IPs — allows multiple devices to share one public IP
- DHCP server: Automatically assigns IP addresses to connected devices
- Firewall: Basic packet filtering — stateful inspection on home routers
- Routing protocols: BGP, OSPF, EIGRP — learns routes dynamically from other routers
- QoS: Prioritizes traffic — critical for VoIP and video conferencing
When to Use Each Device
| Use Case | Device |
|---|---|
| Connect PCs in same office/floor | Switch |
| Connect office to internet | Router |
| Connect two different offices | Router (+ WAN link) |
| Segment office into departments | Managed switch (VLANs) |
| Route between VLANs without a router | Layer 3 switch |
| Power IP phones/cameras/WAPs | PoE switch |
| Home network | Home router (switch + router + WAP combined) |
Modern Home Router — All Three in One
Your home “router” is actually three devices in one box: a router (routes between your LAN and the internet), a switch (the 4 LAN ports on the back), and a wireless access point (the WiFi). In enterprise networks, these functions are handled by separate dedicated devices for performance and reliability.
Related Articles
- Network Devices Explained — Complete Guide
- What is a Network Switch?
- At Which OSI Layer Does a Router Operate?
- OSI Model Complete Guide
- What is a VLAN?
- Best PoE Switches 2025
Frequently Asked Questions
Can a switch replace a router?
A standard Layer 2 switch cannot replace a router — it cannot route traffic between different IP networks. However, a Layer 3 switch can route between VLANs within the same organization. You still need a router (or firewall with routing capability) to connect to the internet or other external networks.
Does a router have a MAC address?
Yes. Every router interface has a MAC address for Layer 2 communication and an IP address for Layer 3 routing. When a device sends data to the router (its default gateway), it uses the router’s MAC address in the Ethernet frame header.
What is the default gateway?
The default gateway is the router’s IP address that devices send traffic to when the destination is outside their local network. For example, if your PC has IP 192.168.1.10 and the router is 192.168.1.1, the default gateway is 192.168.1.1.
Is a firewall a router?
A firewall can perform routing functions, but its primary purpose is traffic filtering and security enforcement. A router’s primary purpose is path selection and packet forwarding. In enterprise networks, the firewall sits between the router and the internal network, inspecting traffic the router has already forwarded.
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