Network Hubs

"Logical topology, or signal topology, is the arrangement of devices on a computer network and how they communicate with one another. How devices are connected to the network through the actual cables that transmit data, or the physical structure of the network, is called the physical topology. Physical topology defines how the systems are physically connected. It represents the physical layout of the devices on the network. The logical topology defines how the systems communicate across the physical topologies.
Logical topologies are bound to network protocols and describe how data is moved across the network. ...
EXAMPLE : twisted pair Ethernet is a logical bus topology in a physical star topology layout. while IBM's token ring is a logical ring topology, it is physically set up in star topology." [Logical topology. Wikipedia]
This Cisco logical computer network diagram example was created using the ConceptDraw PRO diagramming and vector drawing software extended with the Cisco Network Diagrams solution from the Computer and Networks area of ConceptDraw Solution Park.