If one of the switches is reporting collisions then it must be operating in half duplex mode. If one device is operating in half duplex mode and the connected device is operating in full duplex mode, one of the symptoms frequently is collisions on the device in half duplex mode.
I suggest that you do show port or show inteface on both switches and check the setting of duplex and speed. The 3560G should be using auto to negotiate speed and duplex. I suspect that the negotiation is failing on speed or duuplex and that the 3560G is operating in half duplex. If you do find a duplex mismatch and correct it then the issue with collisions should be resolved.
If you have access to your switch but not to the other switch it becomes more complicated to troubleshoot but not impossible. I would suggest that you post the output of show interface for the interface that connects to the other switch. I suspect that it will show that it is operating in half duplex mode. Half duplex is the resulting mode when the switch attempts to negotiate duplex but can not successfully negotiate duplex and I suspect that this is the case. I would probably suggest that if you can not get someone to access the other switch and check its interface that you hard code duplex full on your switch and see what happens.
We are pleased to announce availability of Beta software for 16.6.3.
16.6.3 will be the second rebuild on the 16.6 release train targeted
towards Catalyst 9500/9400/9300/3850/3650 switching platforms. We are
looking for early feedback from customers befor...
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