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Legacy Forums => General Discussion (Legacy) => Topic started by: Terry on November 23, 2003, 08:33:42 PM
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As the topic says, how can I determine whether an interface is running 10 or 100 Mbps, and is it running full or half duplex. I just installed a new switch and am wondering if I'm getting everything I can out of it. And no, the switch doesn't have any management features, so I can't check on that side of things.
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Your switch may be unmanaged but the lights on the front indicate 10/100 and Half/Full duplex modes.Terry wrote:
>
> As the topic says, how can I determine whether an interface
> is running 10 or 100 Mbps, and is it running full or half
> duplex. I just installed a new switch and am wondering if
> I'm getting everything I can out of it. And no, the switch
> doesn't have any management features, so I can't check on
> that side of things.
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DREi wrote:
>
> Your switch may be unmanaged but the lights on the front
> indicate 10/100 and Half/Full duplex modes.Terry wrote:
> >
Nope, just connection and traffic.
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Have you tried "ifconfig -a" at the command line?
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Should I be looking for something specific on the interface? Doesn't look like it shows much more then what ifconfig does, unless this line means something...
EtherTalk Phase 2 addr:65280/28
Other then that I don't see anything that may confirm the interface is running 10 or 100 Megs.
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mii-tool
--or--
mii-tool -v
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Thanks Scott, I think we're almost there. That command confirms that the card will do 100Meg (which I was only 95% sure it would), but is there anything here that confirms it IS running 100?
[root@pdc root]# mii-tool -v
eth0: negotiated 100baseTx-FD flow-control, link ok
product info: vendor 00:10:18, model 23 rev 6
basic mode: autonegotiation enabled
basic status: autonegotiation complete, link ok
capabilities: 100baseTx-FD 100baseTx-HD 10baseT-FD 10baseT-HD
advertising: 100baseTx-FD 100baseTx-HD 10baseT-FD 10baseT-HD flow-control
link partner: 100baseTx-FD 100baseTx-HD 10baseT-FD 10baseT-HD flow-control
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> link partner: 100baseTx-FD 100baseTx-HD 10baseT-FD 10baseT-HD flow-control
The 'link partner' line lists all the confirmed speeds to the next hop. Hence you have a 100 FD link to your switch. Congratulations ;-)
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Also....
dmesg |grep eth0
Will give this result
[root@dev root]# dmesg | grep eth0
e100: eth0 NIC Link is Up 100 Mbps Full duplex
HTH Byte
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Or...
man mii-tool
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Thanks Michiel, Byte, that command doesn't give me any output when I use it.
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mii-tool tells you at what speed the interface is running. That's the first line of output -- eth0: negotiated 100baseTx-FD flow-control, link ok.
If you don't trust the output of mii-tool, then you need to trust your link lights, or if you don't have any link lights, then you'll need to attach a sniffer than can tell you the speed, or if you don't have a sniffer, then you can perform a few file transfers and compute the speed.
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I do trust it, hence the thanks to Michael, which I now see should have been to both of you. Thanks Scott. And I totally missed the "negotiated" line the 1st time. Thanks again.