I'm studying from Lammle book on routing and switching. The setup in the picture is in the book. how can I connect one port of a device to more than one device (as in the figure), and how can I connect two hosts to the same port on a switch or router? I don't know what simulator the book is using, but I'm using Cisco Packet Tracer. enter image description here

Another question: how using serial connection is different from the Ethernet connection?

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The whole point of a network is that all devices connected to it can talk to each other. Each device will needs its own port though. Nowadays, you connect a device to the network through a switch port; the switch works as a central concentrator and traffic exchange, directing packeted data to wherever it's intended to go.

The picture is showing a (logical) layer 3 network layout. A physical layer layout would show all the wires and ports.

A COM-style serial port is a connection between exactly two devices (1:1 relation). A network offers many to many (N:N relation).

Note that at the very bottom layer Ethernet isn't too much more than a simple serial connections, but there's a lot of functionality layered on top that makes it work as a network.


It's all about what you are trying to do, you can for example use a layer 2 device between routers.

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