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Having trouble installing a piece of hardware? Want to know if that peripheral is compatible with Linux?


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Old 04-03-2003, 10:43 AM   #1
Registered: Nov 2002
Distribution: Debian testing.
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cable modem / network cards + auto neg.


is it more preferable to set network cards to use 100mb/s full duplex, if the "other side" is known to support it? ... my linux box auto negotiates with the cable modem. If i set my NTL cable modem to 100mb/s full duplex, the linux NIC only discovers half duplex.. so i set it to auto sensing and it works fine, at 100mb/s full duplex.

however, i can set the NICs of all the boxes on the LAN (connected to 100mb/s switch) to 100 full duplex and they all work ok .. so it is more preferable to set it manually, rather than using auto sensing, when you can?


Old 04-08-2003, 03:50 PM   #2
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Really, it doesn't matter, a cable modem's max badwidth is something like 150k/sec, full or half duplex 100Base-T and we're talking a difference between 10Megs/sec or 8-ish... or in relative terms, do you want the card to give you 56 times more than the cable modem can or 72 times more?

But, if you ever need to crank it, auto-sensing always dorks something up eventually, and as long as the intermediate, the hub, switch, etc. can handle the higher band, ethtool it up to full... I've got a lot of weird old cranky cards that need to be spanked into behaving at full-duplex. As for the cable modem, I'de just blame it on the oddity of the hardware you don't have real control over.

Old 04-08-2003, 04:20 PM   #3
Registered: Nov 2002
Distribution: Debian testing.
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i have found the mii-diag tool, and mii-tool programs.

These allow me to force the cards into Full Duplex, and turn off auto negotiation.

Old 04-09-2003, 05:27 AM   #4
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Cable modem max bandwidth is around 1 megabite to 30 megabit. Internet path ways vary so you get a bandwidth of 1 kilobyte to infinite kilobytes.

For half-deplux and full-deplux. You don't need to change them unless you have several dozen computers on your network. New NIC enable full-deplux at 100 megabit by default.


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