Attached is the current topology of our network. RSTP is enabled on all switches except for the Core1 switch.
All root priorities on the switches are set to 32768 except for the the 3 core switches indicated.
When I enable RSTP on the core 1 switch(all ports) it sets all the ports to forwarding except for ports 2 and 4 which are going to core 2 and core 3 respectively.
It sets the port roles on both 2 and 4 to backup port and blocks them.
Core 1 and Core 2 are connected via a single Gbit line and Core 1 and Core 3 are also connected via a single Gbit line. Any ideas appreciated.