Brouter: the transparent bridge with shortest path in interconnected LANs

!ikansparency is a popular feature in a distributed system where users can access any local or remote resources just as if they were local. As different units in the distributed environment can be integrated into a single unit by means of a distributed operating system, so can multiple LANs be connected by transparent bridges and appear as one LAN to upper layer protocols and end stations. End stations just transmit their packets on their local LAN8 and leave the forwarding task to bridges. Transparency of the interconnected LANs requires 'self learning' at bridges. The main problem of self learning is packet looping. Thus, a "spanning tree " algorithm was developed to eliminate loops in networks. However, two main disadvantages of the spanning tree solution are non-shortest path routing and resour~e wastage. In this paper, a protocol is proposed which combines the features of transparency and shortest path. The result is a bridge which supports Self learning and distributed routing computation. Since this bridge has all routing facilities as a router, it is called 'brouter" (ie. bridge+router). Brouters are compand with current bridge schemes. Also, performance aspects of the protocol are ezamined.