Cabletron Systems NB20E Manual De Usuario

 

To ensure the integrity of the network, primary data paths through 
designated bridges, and redundant data paths through alternative bridges 
are determined in each LAN or loop configuration in the network. A LAN 
segment’s designated bridge is the bridge in a LAN or loop configuration 
with the lowest cost path of transmission from that LAN segment to the 
root bridge. The lowest cost path can be translated in a general way to 
mean the data transmission path to the root that is most economical.

The bridges in the network send out BPDUs to the other bridges so that 
they can all learn which is the bridge in the network, or in a potential loop 
configuration, with the lowest cost path to the root. The bridges can then 
determine their own priorities and roles as designated or redundant 
bridges. Redundant bridges are “blocked” from forwarding packets, but 
they continue to receive topology information.

Figure 1-2 provides a sample illustration of how a potential data loop is 
prevented in a simple multibridge environment. A data loop exists