A switch running ESRP should not simultaneously participate in STP for the same VLAN(s). Other switches in the VLAN being protected by ESRP may run STP; the switch running ESRP forwards, but does not filter, STP BPDUs. Therefore, you can combine ESRP and STP on a network and a VLAN, but you must do so on separate devices. You should be careful to maintain ESRP connectivity between ESRP master and slave switches when you design a network that uses ESRP and STP.