3com 510 Manual De Usuario

 

 

 

Multiple Remote Bridges

 

 

With only a single physical path between LANs, the 

 

network is susceptible to link and bridge failures. In 

 

the event of a failure, the connection between any of 

 

the LANs upstream or downstream of the point of 

 

failure will be broken. A more resilient network of 

 

interconnected LANs can be established by providing 

 

more than one link between any two of the LANs. 

 

Normally, this network would soon encounter serious 

 

problems resulting from a loop, around which frames 

 

could endlessly travel if precautions aren’t taken by 

 

the bridges. Over ISDN links a proprietary form of 

 

loop control is implemented. On WAN leased line 

 

links the Spanning Tree Protocol (STP) prevents data 

 

loops. 

 

On startup, the bridges send out frames to enquire if 

 

there are other bridges on the network. By 

 

exchanging information, the bridges block ports that 

 

cause the loops and ensure that there is only ever 

 

one active path through the network. If one of the 

 

links or bridges fail, the other bridges detect this and 

 

reconfigure their ports so that there is once again an 

 

active data path through the network.

Rc.bk : RCAPPA.FRM  Page 5  Thursday, July 10, 1997  9:53 AM