how is bellman ford algorithm useful in networks?

Question

Dijkstra's algorithm is more efficient than bellman algorithm still we use bellman ford algo for negative edges but what do these negative edges even represent in networks? I couldn't find answer to this question anywhere and this question is killing me, i just need a few applications so i can feel that it is really useful.

Answer 1

The Bellman-Ford algorithm is used by DVR protocols like RIP and RIPv2.

From the wiki

Negative edge weights are found in various applications of graphs, hence the usefulness of this algorithm.[2] If a graph contains a "negative cycle", i.e., a cycle whose edges sum to a negative value, then there is no cheapest path, because any path can be made cheaper by one more walk through the negative cycle. In such a case, the Bellman–Ford algorithm can detect negative cycles and report their existence, but it cannot produce a correct "shortest path" answer if a negative cycle is reachable from the source