half duplex full duplex

[iamtheone12345]

Hi guys,

I wanted to know the difference between half duplex and full duplex ratings.

I know half duplex is unidirectional data transfer(send or recieve) and full duplex is bidirectional data transfer.(send and recieve).

So what is the rating 100 mbps on half duplex and 100 mbps on full duplex  mean?(in context to switch port)

Can someone elaborate with an example?

[Jon Marshall]

What do you mean by rating ?

Jon

[iamtheone12345]

Like ratings on the switches.....100 mbps and hubs 100 mbps....

obviously for switch is 100 mbps full duplex and hubs is 100 mbps half duplex.

I wanted to know how is the bandwith distributed on eachport for a hub(100 mbps) and switch(100 mbps)?

[Jon Marshall]

Still not entirely sure i understand what you mean.

100Mbps half duplex will allow for 100Mbps to be sent in one direction.

100Mbps full duplex will allow for 100Mbps to be set in each direction at the same time.

Jon

[iamtheone12345]

Okay....lets say a switch has 24 ports.Its rating is 100mbps.What bandwith can be used by each port?My guess is 100 mbps.But  say a hub has 4 ports and rating is 100mbps.Is the bandwidth available  100/4=25 mbps?

[Jon Marshall]

Each port on the switch could run at 100Mbps full duplex. Whether or not the switch can handle all ports running at 100Mbps is another matter and is to do with switch fabric and oversubscription.

To be honest pretty much any switch would have the switch fabric to support all ports at 100Mbps but if all ports could run at 1Gbps then the switch fabric/oversubscription could become an issue.

Jon

[burleyman]

100 Mbps means that is the maximum speed that data can be sent, has nothing to do with the duplex. You can have 10 Mbps half or full duplex or you can have 100 Mbps half or full duplex.

Half duplex means you can either send data or receive data but not at the same time. So if data is being sent out that link it has to wait until the line is clear before it can receive data on that link.

Full duplex means you can send and receive data at the same time. So if you are sending data you can also be receiving data at the same time.

Mike

[burleyman]

I think you are asking, if you have a 100 Mbps hub and have 8 ports how many Mbps you have fore each port. The answer would be 100 Mbps....same for switches.

Mike

[iamtheone12345]

@Burley man...are you sure about this?all ports in both hubs and switches would have 100 mbps bandwidth available?

[iamtheone12345]

  @Burleyman Cause i read somewhere that the hubports will share the bandwidth which is specified as rating.

[Jon Marshall]

Yes, with a hub the bandwidth is shared because a hub represents a shared segment.

With a switch it has to do with switch fabric as previously explained.

Jon

[iamtheone12345]

@JON ok.So for a hub with 8 ports and 100 mbps rating is the bandwidth available to each port 100/8=12.5 mbps?

[Jon Marshall]

No, it doesn't work like that on a hub. See Mike's last reply.

Jon

[burleyman]

You are correct, hubs will "share" the bandwidth but what you have to remember is only ONE thing can send or receive data at a time so it has available the full 100 Mbps when it is sending or receiving.

Mike

[iamtheone12345]

Okay so its :

For each switch port it is 100 mbps sending and 100 mbps recieving at the same time.

For each hub port only 100 mbps sending at the same time.

Am i correct?