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Few questions on full duplex/ half duplex.
Please correct any incorrect assumptions. Thanks
1. Both 10base T and 100BaseT can run in either half duplex or full duplex.
When 10baseT operates in half duplex, it uses how many pairs? 2 pair? What about when it operates in full duplex? Does it use 2 pair still? The speed of 10baseT half duplex is 10mbps. But does this speed increase if 10baseT is run in full duplex?
2. Now 100baseT operates at 100mbps in half duplex. And it uses all 4 physical wires? 100baseT full duplex uses 2 pair? What is the speed of 100baseT full duplex ....200mbps?
3. Switches provide point to point connections for hosts, so they can communicate in full duplex. What happens if your network card is only capable of half duplex. Does the switch then act like a "hub"?
4. Hubs can only run in half duplex because they dont provide point to point connections. They forward all frames they receive to every connected host.
If you have a 6 port 10/100 hub, and all clients have 100mb nics. The 100mb is spread out over all 6 users.
If you have a 6 port 100mb switch, and all clients have 100mb nics. Each user gets 100mb.
5. What is the point of having a 1gig backbone, if all of your desktops only have 100mb nics?
1. Both 10base T and 100BaseT can run in either half duplex or full duplex.
When 10baseT operates in half duplex, it uses how many pairs? 2 pair? What about when it operates in full duplex? Does it use 2 pair still? The speed of 10baseT half duplex is 10mbps. But does this speed increase if 10baseT is run in full duplex?
2. Now 100baseT operates at 100mbps in half duplex. And it uses all 4 physical wires? 100baseT full duplex uses 2 pair? What is the speed of 100baseT full duplex ....200mbps?
3. Switches provide point to point connections for hosts, so they can communicate in full duplex. What happens if your network card is only capable of half duplex. Does the switch then act like a "hub"?
4. Hubs can only run in half duplex because they dont provide point to point connections. They forward all frames they receive to every connected host.
If you have a 6 port 10/100 hub, and all clients have 100mb nics. The 100mb is spread out over all 6 users.
If you have a 6 port 100mb switch, and all clients have 100mb nics. Each user gets 100mb.
5. What is the point of having a 1gig backbone, if all of your desktops only have 100mb nics?
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4. Switching hubs are/were a short-lived hybrid. http://www.linksys.com/products/product.asp?grid=34&scid=31&prid=148
Anything that says 10/100 "HUB" is one of these hybrids.
Anything that says 10/100 "SWITCH" is a true switch where each and every port is a true collision domain in itself
5. The link itself is full-duplex, but that is not full duplex communication end-to-end between the client and the server.
The 200Mb is "potential" because you get 100Mb each way simultaneously. You can't "push" or "pull" at 200Mb. You can send one file and receive another file at the same time for an aggregate throughput..but remember the full conversations of TCP/IP requries acknowledgements for every packet, so it's more statistical than real.
HTH.. <8-}
Anything that says 10/100 "HUB" is one of these hybrids.
Anything that says 10/100 "SWITCH" is a true switch where each and every port is a true collision domain in itself
5. The link itself is full-duplex, but that is not full duplex communication end-to-end between the client and the server.
The 200Mb is "potential" because you get 100Mb each way simultaneously. You can't "push" or "pull" at 200Mb. You can send one file and receive another file at the same time for an aggregate throughput..but remember the full conversations of TCP/IP requries acknowledgements for every packet, so it's more statistical than real.
HTH.. <8-}
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ASKER
Got ya. So the uplink is shared by all the traffic. A single client can allocate 100mb of bandwidth and thus create a bottleneck. Is it the general rule of thumb, to make the uplink always faster than your clients to prevent bottleneck?
That's a good rule, but it's not always necessary. For instance, I have a switch here that's talking gig to the rest of the network, and has a 12-port gig card for local connections. But the backplane only supports 2.4 gig to the card at any one time, so the odds are that any situation that overloads the uplink is also going to max out the backplane -- adding uplink capacity won't really do much for me in this case. On the other hand, although the local ports are gig, I don't expect any of them to try to stream data at gig speeds in the ordinary course of an average day.
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ASKER
Ok one last time.
Half duplex. Uses 4 wires.
2 of the wires Rx
2 of the wires Tx
But they can only do one or the other, not both at the same time
Full duplex. Uses 4 wires as well.
2 of the wires Rx
2 of the wires Tx
at the same time.
Half duplex. Uses 4 wires.
2 of the wires Rx
2 of the wires Tx
But they can only do one or the other, not both at the same time
Full duplex. Uses 4 wires as well.
2 of the wires Rx
2 of the wires Tx
at the same time.
ASKER
pengwyn, what is a backplane?
ASKER
4. So you're saying there is such thing as a "Switching hub." And depending on the speed of clients, it groups them accordingly. So if we have a mix of 10mb clients and 100mb clients plugged into a "switching hub", then the switching hub creates two collision domains. One is for the 10mb users, the other is for the 100mb users. So essentially it becomes a 2 port switch? Where are "switching hubs" usually found? Is any switch that is 10/100 considered a switching hub?
5. So they key is to have your uplinks operate at greater speeds than your clients. But cant two switches connected via cross over (aka uplink) run at 200mbps if it's full duplex anyway? Meaning all clients and uplinks between switches will all be 200mbps? Confused on this part
Thanks for the great explanation on the rest!