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  #1  
Old 01-09-2009, 01:44 PM
tom tom is offline
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Default half fuplex

Guys,

One of our servers is going to half duplex most of the time. It has 2 interfaces and other interface doesn't any problem. In network side it configured as full and I forced his cart to use it as full and still coming as half duplex. Also, I have switched the cable and have same issue. Our OS is linux, any help would be appreciated.
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Old 01-09-2009, 03:11 PM
Schumie Schumie is offline
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If you force one side of the connection to be full duplex, you inherently break auto negotiation and this will likely be the reason that one side is falling back to half duplex.

You should either force both sides to be full duplex (under linux, you can use the 'ethtool' command to do this) or let autoneg do it's thing!
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Old 01-09-2009, 07:17 PM
tom tom is offline
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Here is the out put. In the switch end set it to FUll duplex , so I forced it to full duplex and didn't fix. Also, I changed the network cable. Do you think the problem with network card? I have restarted eth0 as well didn't help.

ethtool eth0
Settings for eth0:
Supported ports: [ TP ]
Supported link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Full
Supports auto-negotiation: Yes
Advertised link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Full
Advertised auto-negotiation: Yes
Speed: 100Mb/s
Duplex: Half
Port: Twisted Pair
PHYAD: 1
Transceiver: internal
Auto-negotiation: on
Supports Wake-on: g
Wake-on: d
Link detected: yes
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Old 01-09-2009, 08:51 PM
Schumie Schumie is offline
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Quote:
Originally Posted by tom View Post
Here is the out put. In the switch end set it to FUll duplex , so I forced it to full duplex and didn't fix.
Please re-read my post. If you force one end, and do not force the other, it will fall back to half duplex!

Quote:
Originally Posted by tom View Post
Also, I changed the network cable.
This is a configuration issue, not a cable issue - this would have made no difference.

Quote:
Originally Posted by tom View Post
ethtool eth0
Settings for eth0:
Duplex: Half
As you can see, your server is defaulting to half duplex as you haven't forced it to use full.

To force this on your server you would do something like: ethtool -s eth0 speed 100 duplex full

I'd advise you go read some documentation on networking basics to understand this. A good place to start on this topic would be some of the documents on Cisco's web site.
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