Cat5500 speed negotiation

donglee36 · ‎04-04-2007

Hello,

We have a strange problem with our Cat5513.

We get really bad upload speed whenever we hard-coded the port on Cat5500 to 100mb full-duplex.

It gets about 19mb/s download and 18mb/s upload when it's on auto negotiation, however it only gets about 789kb/s upload speed when it is hard-coded to 100mb full. It seems like it's only affecting upload speed since it gets about 17mb/s download speed.

What gives???

Do we have a faulty switch? or buggy CatOS?

Thank you

Craig Balfour · ‎04-04-2007

You've given the speed and duplex configuration for the Cat5500 port but what is the speed and duplex configuration on the remote side?

If both sides are set to auto-negotiate then they should negotiate 100 Mbit/s full duplex and everything should be fast.

However, if the Catalyst 5500 is hard set to 100 Mbit/s full duplex and the remote side is set to auto-negotiate, negotiation will fail and the remote side will probably settle on 100 Mbit/s half duplex. This would be duplex mismatch which will definately cause a slowdown in speed between the two devices and you should also see the error counters climbing on the interfaces.

donglee36 · ‎04-04-2007

Hello,

Thanks for your writing.

We didn't see any error or collision on the ports, and we had same result when we hard-coded 10mb/s full on each side.

Thank you

glen.grant · ‎04-04-2007

Both sides must match , if one side is auto then the other side must be auto/auto . If you hardcode one side 100/full then you "must" hardcode the other also , anything else will give you speed/duplex mismatches .