In a network of LANs connected by bridges, packets are sent from one LAN to another through intermediate bridges. Since more than one path may exist between two LANs, packets may have to be routed through multiple bridges. Why is the spanning tree algorithm used for bridge-routing?
- For shortest path routing between LANs
- For avoiding loops in the routing paths
- For fault tolerance
- For minimizing collisions
According to wiki :
"The Spanning Tree Protocol (STP) is a network protocol that ensures a loop-free topology for Ethernet networks."
Can you explain little bit please, why option $(1)$ is false?
In the simple case where there is at most one direct connection between any two segments of the network, suppose the network topology is not already tree, and that a spanning tree has been selected. There will be some link that is not in the spanning tree ... and the shortest path between the two ends of that link would certainly be to use that link (for a distance of 1 hop) rather than route along the spanning tree (for a distance of at least 2 hops, maybe more).