3Com 3800 User Manual page 100

7-2 C 7: S T P (STP)
HAPTER PANNING REE ROTOCOL
Figure 7-1 Network with an illegal topology
This configuration is illegal because it creates loops that cause the
network to overload. However, STP allows you to use this configuration
because STP detects duplicate paths and immediately prevents (or
blocks) one of them from forwarding traffic.
Figure 7-2 shows an example of enabling STP on the bridges in the
configuration. The STP system has decided that traffic from LAN
segment 2 to LAN segment 1 can only flow through Bridges C and A.
Figure 7-2 Traffic flowing through Bridges C and A