Gigabit link is auto neg to 100M

[davegibelli]

I have two WS-C3750X-48 connected together with both the ports set to auto,however, the ports are running at 100M/full. Cisco even recommend auto-neg but why is it only running at 100M?

I have two pairs with the same issue, this is very strange.

Software is v15.0(2)SE4

[Charles Hill]

Have you verified the cabling?

100M only requires 4 wires, where Gig requires all 8 wires/ four pair.

http://www.hardwaresecrets.com/printpage/How-Gigabit-Ethernet-Works/231

[Martin Carr]

This, verify the standard of the cabling.

Martin

[davegibelli]

Using the "test cable tdr" commands show the cable as normal for all pairs!

I am not physically near the switches but this is very weird as there are four switches connected in a ring. The ports set to trunk are running at 1000/F but the access ports are running at 100/F

[Martin Carr]

Swap the cable to eliminate it, irrespective of this, it may be terminated to an older standard etc, what category is it?

To clarify, what is connected to the access ports, as from your last post it seems it's not the switch, as initially stated?

Martin

[Norberto Salgado]

Have you tried to connect one of the switchs to a different device to check if you've the same issue?

Have you tried to replace the cables as well?