How does collision happen on half-duplex switch port? Possible?

Can collision happen on half-duplex switch port? How?

Let's say PC A and PC B are connected to a Switch on port fa0/1 and fa0/2 respectively. I set port fa0/1 and fa0/2 and both PC NICs to half-duplex mode.
How does it collide? UTP Cables use 2 TX and RX each so the frames are still transmitted and received on different wires.

What are the differences with full-duplex then?

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Comments

Simrid

Correct me if i'm wrong however, full duplex allows synchronous transmission. The means that both PC's can send and receive data at a single time. With half duplex, what if both the pc's try to send at the same time? I believe that is when a collision would happen.

FreddyIW

Simrid wrote: »

Correct me if i'm wrong however, full duplex allows synchronous transmission. The means that both PC's can send and receive data at a single time. With half duplex, what if both the pc's try to send at the same time? I believe that is when a collision would happen.

But the UTP cables transmit and receive on different wires? Why does collision still occur even with half-duplex?

OfWolfAndMan

While in full duplex you can transmit and receive simultaneously, half duplex means you can only do one or another at a time. However, switches isolate collision domains per port, so collisions don't typically happen, unless you have some faulty hardware. However, if you're running a hub or a bridge, then yes you could have collisions and CSMA/CD will be utilized for when a collision occurs.

H3||scr3am

Another misconfiguration that causes collisions as I understand is when the ports are set to full duplex, but the device is only half duplex, this causes a collision every time the full duplex device sends something. It was covered in my CCENT Exam cram book.

pevangel

You're under false impression that the cable dictates what the NIC uses for transmit and receive. It's just a set of wires. A NIC in half duplex will send and receive on the same pair of wires even if there are other pairs available.

OfWolfAndMan

H3||scr3am wrote: »

Another misconfiguration that causes collisions as I understand is when the ports are set to full duplex, but the device is only half duplex, this causes a collision every time the full duplex device sends something. It was covered in my CCENT Exam cram book.

This is correct as well. You will see a flashing Amber/green light on a port when this happens

FreddyIW

Thanks guys I got it now