Help. Questions with networking. It has to do with switch.?

Question

Please bear with me. I'm totally new to this. I'm pretty sure I'm about to say something nonsense to you guys. Please correct me.

The book I'm reading says:
"each device on
every segment plugged into a switch can transmit simultaneously. At least, they can as long as
there is only one host on each port"

If one network consists of 2 pcs, and this network is connected to a switch. From what I understand, these 2 pcs cannot transmit simultaneously because they reside within one collision domain. So, I don't understand why the author is saying the above statement.

To be honest I don't quite get what it means to say "as long as
there is only one host on each port" I read a definition of "host", but I don't get it. The 2 pcs I used in my example represent 2 hosts or just 1 host?

I'm just lost. Help will be greatly appreciated.
Thank you very much.

Answer 1

A switch has as many collision domains as there are ports on it. If you have a switch that has 8 ports on it, then that switch has 8 collision domains. Because of this, the computers are able to transmit simultaneously.

A host is simply any computer that has an IP address attached to it. If you connect 2 PC's, then you have 2 hosts.

Answer 2

Hi. The statement you make does sound a little off. In a conventional switch, all the ports (jacks) have one cable (usually of type twisted pair) connecting the switch to the host (usually a PC). This is a point-to-point link between the host and the switch. Any switch has at least 4 ports and can have a lot more. Because of the point to point nature of the connections, all hosts can transmit simultaneously to the switch. Now assuming that there are more than one PCs connected to that cable which goes to the switch (which is possible if you use say a BNC instead of twisted pair), then that means that multiple PCs are connected to that one port on that switch. In such a scenario, only one PC will be allowed to transmit to the switch. These multiple PCs can be considered as a segment. Your example network has 2 PCs. Each PC will be connected to the same switch. They can both transmit simultaneously since there are two independent cables and hence two non-overlapping point to point connections. If you had used a hub instead, that would not be possible. Look up the difference between a hub and a switch if you need to.

Answer 3

Thank you for your effort and valuable time (both of U)

But, I need a little clarification on one thing.
When you say:
"Now assuming that there are more than one PCs connected to that cable which goes to the switch (which is possible if you use say a BNC instead of twisted pair), then that means that multiple PCs are connected to that one port on that switch"

In this scenario, is it correct to say that there are multiple hosts on that one port of the switch???

Answer 4

"they can as long as there is only one host on each port"

- Meaning not multiple machines going into that one port (such as +another switch with -> multiple machines)