7.2 Spanning-Tree Protocol  
  7.2.6 Spanning-tree recalculation  
A switched internetwork has converged when all the switch and bridge ports are in either the forwarding or blocked state. Forwarding ports send and receive data traffic and BPDUs. Blocked ports will only receive BPDUs.

When the network topology changes, switches and bridges recompute the Spanning Tree and cause a disruption of user traffic.

Convergence on a new spanning-tree topology using the IEEE 802.1D standard can take up to 50 seconds. This convergence is made up of the max-age of 20 seconds, plus the listening forward delay of 15 seconds, and the learning forward delay of 15 seconds.

 

Lab Activity

Lab Exercise: Spanning-Tree Recalculation

In this lab, the student will create a basic switch configuration and verify it and observe the behavior of spanning tree algorithm in presence of switched network topology changes.

   
 

Lab Activity

e-Lab Activity: Spanning-Tree Recalculation

In this lab, the students will create a basic switch configuration and verify it.

   
 

Web Links

Understanding Spanning-Tree Protocol

http://www.cisco.com/univercd/cc/ td/doc/product/ rtrmgmt/sw_ntman/ cwsimain/cwsi2/ cwsiug2/vlan2/stpapp.htm