One NE40E and RPR dual-link of A corporation form the ring to test RSTP. Both sides connect testmeter SmartBits. When master link is down, the time when the traffic switches over backup link is more than 2 seconds ruled by RSTP protocol.
Set two ports of testmeter as Edge port. The test result is 1.08 second.
The test result is 30 seconds. Compared with RSTP protocol, it is of no use. When master link is down, the whole topology should compute STP again. The port connecting testmeter need calculating again. It seriously influences switchover time of the traffic. If the port connecting testmeter is taken as user's port, it does not need STP calculation. It can be set as Edge port or STP protocol is disabled.
The port of testmeter is taken as user port. Regard RPR device of A corporation as one L2 switch. It is just transmission device.