HP Cisco Nexus 5000 Cisco Nexus 5000 Series Switch CLI Software Configuration - Page 145

Chapter 8 Configuring Rapid PVST+ Information About Rapid PVST+ Send feedback to [email protected] Figure 8-5 Sample Topology Demonstrating Port Roles Bridge_ID=1 Root_ID =1 Bridge_ID=2 Root_ID =1 Bridge_ID=3 Root_ID =1 Bridge_ID=4 Root_ID =1 Bridge_ID=5 Root_ID =1 Bridge_ID=6 Root_ID =1 Alternate port Backup port Designated port Root port Active link Blocked link Bridge_ID=7 Root_ID =1 182775 Port States This section describes the Rapid PVST+ and MST port states: • Rapid PVST+ Port State Overview, page 8-11 • Blocking State, page 8-12 • Learning State, page 8-12 • Forwarding State, page 8-12 • Disabled State, page 8-13 • Summary of Port States, page 8-13 Rapid PVST+ Port State Overview Propagation delays can occur when protocol information passes through a switched LAN. As a result, topology changes can take place at different times and at different places in a switched network. When a LAN port transitions directly from nonparticipation in the spanning tree topology to the forwarding state, it can create temporary data loops. Ports must wait for new topology information to propagate through the switched LAN before starting to forward frames. Each LAN port on a software using Rapid PVST+ or MST exists in one of the following four states: • Blocking-The LAN port does not participate in frame forwarding. • Learning-The LAN port prepares to participate in frame forwarding. • Forwarding-The LAN port forwards frames. • Disabled-The LAN port does not participate in STP and is not forwarding frames. OL-16597-01 Cisco Nexus 5000 Series Switch CLI Software Configuration Guide 8-11