7.2 Spanning-tree Protocol  
  7.2.7 Rapid Spanning-Tree Protocol  
The Rapid Spanning-Tree Protocol is defined in the IEEE 802.1w LAN standard. The standard and protocol introduce the following:
  • Clarification of port states and roles
  • Definition of a set of link types that can go to forwarding state rapidly
  • Concept of allowing switches, in a converged network, to generate their own BPDUs rather than relaying root bridge BPDUs

The “blocked” state of a port has been renamed as the “discarding” state. A role of a discarding port is an “alternate port”. The discarding port can become the “designated port” in the event of the failure of the designated port for the segment.

Link types have been defined as point-to-point, edge-type, and shared. These changes allow failure of links in switched network to be learned rapidly.

Point-to-point links and edge-type links can go to the forwarding state immediately.

Network convergence does not need to be any longer than 15 seconds with these changes.

The Rapid Spanning-Tree Protocol, IEEE 802.1w, will eventually replace the Spanning-Tree Protocol, IEEE 802.1D.

 

Web Links

Understanding Rapid Spanning-Tree Protocol (802.1w)

http://www.cisco.com/warp/
public/473/146.html