STP parameters used comprises a bridge ID (Bridge ID), path cost (Path Cost) and a port ID (Port ID). I am here to say that the path overhead cost, IEEE802.1D standard was originally defined as the cost of 1000Mbit / s divided by the bandwidth of the link (in Mbit / s). For example, the overhead 10BaseT link is 100 (1000/10), Fast Ethernet and FDDI overhead is 10. With the advent of Gigabit Ethernet technology and a higher rate, this definition there have been some problems: overhead as integer rather than floating storage. For example, the overhead of 10Gbit / s is 1,000 / 10,000 = 0.1, which is an invalid overhead. To solve this problem. IEEE changed the definition of an inverse. Appeared overhead definitions updated.
Reproduced in: https: //blog.51cto.com/14216988/2409716