Q.How will a Bus and Ring topology behave in case a Node is down?

This is a plain theory question — it asks for a comparative explanation of fault tolerance in two specific network topologies.

Bus Topology — Node Failure

In a Bus topology, all nodes are connected to a single central cable (the backbone). A node that is down simply stops transmitting or receiving data. Because each node is a passive tap on the cable, a single dead node does not break the network for the remaining nodes — they can still communicate with each other as long as the backbone itself is intact.

Ring Topology — Node Failure

In a Ring topology, each node is connected to exactly two neighbours, forming a closed loop. Data travels in one direction (or both, in a dual-ring design), passing through every intermediate node. If a node goes down, the ring is broken — the path from one side of the failed node to the other is lost. In a single-ring (unidirectional) setup, the entire network fails because no data can complete the loop. …

Understanding the Question

This is a plain theory question about network topologies — specifically, how fault tolerance differs between Bus and Ring topologies. The key idea is that topology determines how data flows and what happens when a connection breaks.

Bus Topology — Single Point of Failure

In a Bus topology, all nodes are connected to a single central cable (the backbone). Data travels along this cable, and every node checks if the data is addressed to it.

When a node goes down:

• The node itself stops receiving/transmitting, but the backbone cable remains intact.
• However, if the failed node physically breaks the cable (e.g., a loose T-connector), the entire network segment on that side becomes unreachable.
• Even if the node just powers off without breaking the cable, the network continues to function for other nodes — but this is rare in practice because most bus implementations use passive taps that can cause signal reflection or termination issues.

Result for Bus: A node failure typically disrupts the entire network segment because the bus is a shared medium. If the backbone is broken, all nodes beyond the break lose connectivity.

Ring Topology — Single Ring vs. Dual Ring

In a Ring topology, each node connects to exactly two neighbours, forming a closed loop. Data travels in one direction (or both, in a dual ring).

Single Ring (unidirectional):

• Data passes through every intermediate node. If one node goes down, the ring is broken — data cannot reach nodes beyond the failed node.
• The entire network fails because the loop is no longer closed.

Dual Ring (bidirectional, e.g., FDDI):

• Two rings carry data in opposite directions. If a node fails, the two rings can "wrap" around the failure, re-routing data through the other ring. …