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Commonly confused · Networking Fundamentals

Hub vs Switch vs Router: What's the Difference?

A hub repeats every bit out every port, a switch forwards frames only to the port where the destination MAC address lives, and a router forwards packets between different IP networks. Each operates at a higher OSI layer than the one before it.

HubSwitchRouter
OSI layerLayer 1 (Physical)Layer 2 (Data Link)Layer 3 (Network)
Forwarding decisionNone; repeats out all portsDestination MAC address via MAC address tableDestination IP address via routing table
Collision domainsOne shared collision domainOne per portOne per interface
Broadcast domainsOneOne per VLANOne per interface; routers block broadcasts
DuplexHalf duplex onlyFull duplex per portFull duplex per interface
ConnectsDevices on one segmentDevices in the same LAN or VLANDifferent networks or subnets
Remember it

Hubs shout, switches whisper to one MAC, routers mail letters between towns.

Exam tip

Exams love asking how many collision and broadcast domains a diagram contains. Count each switch or router port as a collision domain, and each router interface or VLAN as a broadcast domain; a hub adds none.

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