By a customer of my I had a problem that the uplink of core switches are going to error-disabled state when connecting a Cisco switch to the existing network.
Here is a overview of our netwerk.

I connected the Cisco 3560 switch to a HP switch (ASC2). The configuration of the uplinks on the Cisco switch and the HP switch are the same as the connection to HP switch (EBG01) that is connected to the Cisco 4500 switch (Core).
On the Cisco 3560 switch I give the command "no ip routing".
Can anyone tell me what was the reason why the uplinks of the core switch that is connected to EBG01 are going to error-disable state? In de log I only see that the ports are going to error disable stat but without a reason.