Q.How will a bus and ring topology behave in case a node is down?
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Start your 14-day free trial to unlock the full solution →In a bus topology, a single node failure does not disrupt the network, but in a ring topology, a single node failure can break the entire communication loop unless a bypass mechanism exists.
When we talk about network topologies, the key difference between a bus and a ring lies in how data travels and how dependent the network is on each individual node. A node is simply any device connected to the network—a computer, printer, or server. Understanding what happens when one of these nodes goes down reveals the fundamental design philosophy behind each topology.
In a bus topology, all nodes are connected to a single central cable, often called the backbone or bus. Data sent by one node travels along the entire length of this cable, and every other node "listens" to see if the data is addressed to it. The crucial point here is that the nodes themselves are passive—they do not regenerate or forward the signal. They simply tap into the cable to read or send data.
Think of a bus topology like a single railway track with stations along it. A train (data) passes every station, but only the station that matches the ticket (address) stops the train. If one station is closed (node down), the train still runs past it without any issue.
So, if a node in a bus topology fails or is powered off, the rest of the network continues to function normally. The failed node simply cannot send or receive data, but it does not block the signal for others. The only way a bus topology fails catastrophically is if the main cable itself is cut or damaged—that breaks the entire network. A single node failure, however, is isolated and harmless to the rest.
Now consider a ring topology. Here, each node is connected to exactly two neighbours, forming a closed loop. Data travels in one direction (or sometimes both) around the ring, passing from node to node. Each node acts as a repeater: it receives the signal, checks if the data is for itself, and if not, regenerates and forwards the signal to the next node.
In a ring topology, every node is an active participant in the data path. If one node fails, the loop is broken, and data cannot travel past that point. This means the entire network goes down for all nodes beyond the failure.
The failure of a single node in a ring topology is therefore a serious event. The network becomes partitioned—nodes on one side of the failure cannot communicate with nodes on the other side. In a simple unidirectional ring, the entire network effectively stops working because the data cannot complete its journey around the loop. This is the major vulnerability of a standard ring topology. …
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