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Collisions caused by NIC?

By LabRaT ·
I just plugged a brand new server into a Bay Networks 10/100 24-port hub and the collision lights went crazy. I tried new cables and got the same thing. But when I move the cable to 2 or 3 specific ports, the hub looks fine with no collision lights. I have moved several other systems around on the hub but they do not cause any amber lights. Plugged the new system into a second Bay Networks hub (stacked with the first hub) and got collisions again.

Initially, I thought the NIC was bad (or headed that way) even though it was new. When problem wasn't consistent on all ports, I thought I might have ports going bad on that hub. But when I got the same problem on a different hub, I went back to thinking it was a bad NIC.

Here's the questions: 1) The server and its NIC look OK on a few ports; Is that normal and I should just find a port it works on and not worry? 2) The NIC is builtin on the motherboard and under warranty; should I have the motherboard swapped out before I build the server up?

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by P. Dickason, CNE, MCSE, CCA In reply to Collisions caused by NIC?

The card is most likely ok. There is a mismatch between the speed and duplex setting between the card and the hub. For example, the hub has ports configured to 10 mbps half duplex and the server is configured for 100/full. Or whatever, something doesn't match up. Hopefully your hub has some sort of management program where you can go in and change the port speed/duplex setting to match the servers. I would stay away from auto speed and duplex and match up both peices of equipment. Hope this helps.
Pete

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by P. Dickason, CNE, MCSE, CCA In reply to

oh wait...did you say HUB? Hub's cannot do full duplex. Make sure the server setting for the card is half duplex. Should fix your problems. This could be a problem where auto is not picking up settings correctly. Thats why I don't use auto.
Pete

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by LabRaT In reply to

Poster rated this answer.
Thanks, Pete. The hub and cards are all set on auto. I understand your reasons for suggesting a fixed rate. There are circumstances here out of my control so auto is the best (and most cost effective way) to configure this net.

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by LabRaT In reply to Collisions caused by NIC?

There aren't any NIC drivers running to set the software-enabled rates as Pete suggested. This is a "clean" server with no OS. I just plugged it in to get a link and the hub started flashing amber on that port and its collision light scale. I am bringing 2 identical model servers online. The first server (serverA) doesn't cause any collisions (and I have plugged it into ports right after the problem one -serverB). I don't think it is a setting or configuration problem because it should be identical to the first server at this point with only BIOS and blank HDDs. But I am curious as to why it seems OK on a few ports on both hubs. I have plugged serverA into every port here and get no amber lights but serverB lights up both hubs except on maybe 4-5 ports on both hubs. I don't have any kind of network analyzer to see what is being sent when this system plugs in.

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by LabRaT In reply to Collisions caused by NIC?

NIC must have been bad. I swapped out the motherboard and the new system was fine. Pete, thanks for your suggestions.

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by LabRaT In reply to Collisions caused by NIC?

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