Simple doubt in switches.

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Hello,
A very very straightforward query here.
I'll attach a picture here,

Here in the pic above it says that Switches separate/isolate collision domains since they give full bandwidth to the PTP connection. But, consider this scenario,

1. A is communicating with B, but C tries to communicate with A too. In this case, won't there be a possible collision? So, to prevent this, does CSMA-CD help??
   Thanks...

@Atharva-Bet,

Let me ask a question to help you gauge your understanding of connectivity devices and collision domains and broadcast domains.

• When we discuss the behavior of a hub, what defines the collision domain and broadcast domain?
  All ports in a single broadcast and collision domain?

• When we discuss the behavior of router, what defines the collision domain and broadcast domain?
  Each port is a broadcast domain. do not tend to worry about collisions

• When we discuss the behavior of switch, what defines the collision domain and broadcast domain?
  ?
  ?

@Ronnie-Wong said in Simple doubt in switches.:

Okay cool Sir, I'll try to answer your questions

I understand that when more are the number of collision and broadcast domains (obviously these 'more' are created by breaking huge ones not separately existing), the better it is for a network because the chances of collisions decrease. I will give answers in terms of separation of domains.

1. Hubs neither separate collision domains nor broadcast domains. They in fact create and enlarge them.

2. Switches are a little smarter. They separate larger collision domains because it's every port in itself is only a collision domain. But they are unable to separate broadcast domains.

3. Router is the smartest. Separates both kinds of domains.

But then in my previous post in this thread, my question was like let's say if A is communicating with B & C is also simultaneously trying to communicate with A let's say, for example, so like will there be separate bandwidth/channel of communication allotted to A-B & C-A? Collisions are possible? If yes, will CSMA-CD help??

@Atharva-Bet said in Simple doubt in switches.:

@Ronnie-Wong said in Simple doubt in switches.:

2. Switches are a little smarter. They separate larger collision domains because it's every port in itself is only a collision domain. But they are unable to separate broadcast domains.

But then in my previous post in this thread, my question was like let's say if A is communicating with B & C is also simultaneously trying to communicate with A let's say, for example, so like will there be separate bandwidth/channel of communication allotted to A-B & C-A? Collisions are possible? If yes, will CSMA-CD help??

Yes. but do you see you answered it. every port is a collision domain. So a collision domain is only on the same port. There are no collisions between ports.

IF PC1 and PC2 were on the same port. Collisions.
IF PC1 and PC2 are on different ports...no collisions.
because collisions only happen on that same port within switches.

I ask those questions because, I knew the answer was there. It wasn't a trick.