Half-Duplex - Full-Duplex 2

[Grenage]

I'm curious as to the nature of full duplex and half. When trying most machines (and servers) at Half-duplex the speed is great and all is well, but at full duplex the speed is considerably slower. I have checked the cables and Switch ports, along with the network cards but there seems to be nothing amiss.

While I am more than happy to leave the cards at 100hdx I was just curious as to why this might be. I know it's common after reading up on google but I failed to get any answers in a language I could understand

 

[Morsing]

On end talks half duplex the other full duplex. You need to set your switch ports on full duplex.

Cheers Henrik Morsing
Certified AIX 4.3 Systems Administration
& p690 Technical Support

 

[wybnormal]

On the switches or endpoints, clear any counters and then run a couple of tests by loading files of various sizes each way. Look at the counters. On full duplex, since you have troubles with that, you will probably see CRC errors or a high collision rate. With a sniffer you would more then likely see a high retransmit rate from one or both of the NICs. Normally this comes down to poor cabling but I have seen low quallity NICs and/or drivers do this. Older HP drivers seem to be prone to this type of error. As a rule, the only NICs I use is INtel Etherexpress 10/100 cards. They have not failed me yet

MikeS
Find me at

http://www.packetattack.com

"Take advantage of the enemy's unreadiness, make your way by unexpected routes, and attack unguarded spots."
Sun Tzu

 

[Grenage]

Ta

Like written above I checked the Switch Ports etc and they appeared to be fine, so I guess I'll give the cabling a going over (CRC errors are indeed generated according to the switch). The card is an Intel 100/S Dual Port Server Adapter.

Thanks again.

 

[jimbopalmer]

one problem is that a AUTO port can never link correctly to a FULL port.


AUTO AUTO works
AUTO HALF works
FULL FULL works
HALF HALF works

AUTO FULL fails
FULL HALF fails

If your switch is not managable and stays in AUTO, you must leave your NIC in AUTO or HALF. If the switch can be set to FULL, then the NIC can be set to FULL.

FULL is nice once you get it set right, but it is best if you can leave both the switch and NIC on AUTO. I tried to remain child-like, all I acheived was childish.

 

[Grenage]

Thanks

The switch is managed and the port and server connections were set manually to 100fdx. I will try your suggestion of using auto on both ends.

Thanks again.