The switch diameter of my customer network environment have been more than 7, and sometimes my customer network have bridge loop problem, ( core switch backplane utilization up to 90%, the packet loss, HSRP have duplicate IP address error message ) but this problem will be recover automatically after 10 mins. So I think it is the spanning-tree topology convergent problem. I think if I increase the STP timer, although the STP convergent time will increase, but it will prevent the bridge loop problem. If switch diameter are 10, what are the suitable value for hello, forward delay & mac age timer? And any consideration for increase STP timer?