Is there a speed difference

[SilentRavens]

Has anyone ever noticed a difference in network performance between Full-Duplex and Half-Duplex mode on a 100Mbps network.

 

[spidey07]

Originally posted by: SilentRavens
Has anyone ever noticed a difference in network performance between Full-Duplex and Half-Duplex mode on a 100Mbps network.

absolutely

 

[gunrunnerjohn]

Try transfering a large amount of data, say a bunch of large files. You'll see a significant difference in half or full duplex. Why do anything but full-duplex anyway?

 

[Abzstrak]

yes, its significant.... depends on what your doing, if your just streaming mp3's from another box, then no it wont matter much.

 

[SilentRavens]

Originally posted by: gunrunnerjohn
Try transfering a large amount of data, say a bunch of large files. You'll see a significant difference in half or full duplex. Why do anything but full-duplex anyway?

Some of my network hardware is really old.

I was asking becuase when I went ahead and timed the transfer of a 127Mb file, I only noticed a small time difference of about 2 seconds between the two.

 

[SilentRavens]

Originally posted by: gunrunnerjohn
Try transfering a large amount of data, say a bunch of large files. You'll see a significant difference in half or full duplex. Why do anything but full-duplex anyway?

Some of my network hardware is really old.

I was asking becuase when I went ahead and timed the transfer of a 127Mb file, I only noticed a small time difference of about 2 seconds between the two.

 

[cmetz]

SilentRavens, network performance has two dimensions: bandwidth, and latency. Duplex does affect the bandwidth, but maybe not all that much, but the latency is where it really gets you. On a half-duplex interface, if another party (or parties) sending a lot of stuff your way, you can't send until the receive is done. So depending on network weather conditions, latency could be high or low. That wide variance is the real killer for many applications, like VoIP and some games (other games just don't like high latency). Half-duplex can also lead to packet loss issues because there is a maximum number of collision retries before a packet just gets tossed, and that's a whole mode of loss that doesn't exist on a FD network.

Duplex mismatches - where one side thinks it's half and one thinks it's full - can manifest themselves as catastrophic performance problems. If your 100Mb/s link between two systems can't move real data at more than like 1Mb/s, you may have a duplex mismatch. Bad stuff.

CSMA/CD was a cool technology, but it's one I'm happy to have in the past. Full-duplex is just plain better.