1-16 CHAPTER 1: INTRODUCTION
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Spanning Tree Algorithm And Protocol (STAP)You can make your network more resilient by adding bridges and
network segments. If a network segment or bridge fails, traffic
can still travel through the network by using the additional
bridges and network segments.
The key to resilience is the number of paths through the network.
Multiple paths, however, result in active loops. Active loops
introduce redundant traffic to the network, which can quickly
degrade overall network performance and, more importantly,
breaks network rules.
In the example shown in Figure 1-15, three network segments are
connected by three bridges, causing an active loop. Device B
transmits a packet for device E. Bridges 1 and 3 receive the packet
and forward it. Device E receives the packet from bridge 1 but
also receives a copy from bridge 2 (via bridge 3) .
Figure 1-15 An Example Active Loop
A networking standards committee of the Institute of Electronic
and Electrical Engineers (IEEE) recognized and solved the problem
by introducing the Spanning Tree Algorithm and Protocol (STAP).
The STAP has become a standard bridge feature.