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Switch Connection

WE currently have 3500XL series of switches. A set in our computer room. A set in a remote closet,(on the same floor) and a set one floor up. this is all connected with a fiber connection. Each remote site is going to the computer room on separate fiber line. I believe that the fiber is going into a 1000BaseX GBIC at each end for both runs.

The connections from the computer room switches and the clost on the same floor are connecting at 100 MIPS, while at the remote site upstairs everything is connecting at 10 MIPS.

The switch is 3524 XL.

We have tried to forced a connection at 100 MIPS, but no deal. We have configured this switch the same as the others, but can not established a 100MIPS at full duplex. The PCs at the other end are Dells with 3Com NICs.

Any ideas?




Re: Switch Connection

Could be a configuration issue:

Check the configuration of the switches, to see if the 10/100 ports are set to autodetect speed and duplex. If they're manually set to 10 or 100, half or full duplex, then there will be no negotiating with the workstation NICs.

Remember, if you try to force a connection to a certain speed and duplex, it must be set the same on both on the switch AND on the computer's NIC. Difference in speeds means connection won't work at all. Difference in duplex will result in strange problems: low-volume traffic like pings will seem to work fine, but higher-volume traffic like web access will be erratic. Signs of duplex mismatch on a link are CRC errors on the "full" side, and late collisions on the "half" side.

Could be a software issue:

Check the version of software running on the switches at the remote site upstairs. Are they running the same version as the ones downstairs? Maybe they're running older code.

Check with Dell and 3Com for updated drivers for the NICs. It's possible that if they're running old code, they may not autonegotiate properly with the switches.

Could be a hardware issue:

Exactly what model of 3Com NICs are they using upstairs in the Dells? If they're Ethernet only, then they can only do 10-megabit, which would explain everything.

Could be a network design issue:

Confirm what kind of fiber links you have between the switch locations. Cisco's GBICs will only run at 1000 full duplex. If you have switches with Fast Ethernet fiber ports or you're using Fast Ethernet media converters, they will run at 100 only, but the duplex needs to be set: default is usually half, but full is better between switches. (Full duplex has better throughput and supports longer fiber cable distances than half.)

How are the sets of switches interconnected within each closet?

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