Let's says one the customer is using collapse core design. The core layer actually consist of distribution layer, the distribution layer actually is part of core. The distribution switches is stackwise with same model C3750 and using 4 cable as etherchannel with the core switches, both model is C4506. Will this lead to STP loop? The core layer switches is H.A. using VRRP.
The other thing is that the access layer switches C2960, one of the switches is directly connect to core switches while some switch in access is connecting to distribution switch. You think this design have any flaw? Please refer to the picture upload. Thanks guys!