Meghadoot

- A Hybrid Wireless architecture

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Link Cache instead of a Path Cache

Instead of a path cache - where each entry is a full path from the source to the destination - at the MN, we maintain a link cache, wherein each individual link (hop) in the routes returned in Route Reply packets (or otherwise learned) is added to a graph data structure stored at this node. This link cache is the partial view of the network topology (as seen by the MN). To search for a route in link cache, the MN uses the Dijkstra's shortest-path algorithm to find the current best path through the graph to the destination node.

Although using a link cache is more CPU intensive compared to a simple path cache, the advantages far outweigh the cost incurred. A link cache is much more powerful than a path cache in its ability to effectively utilize all of the potential information that a node might learn about the state of the network. In particular, links learned from different route replies or from the packets that are being forwarded by this MN can be merged together to form new routes in the network, which is not possible in a path cache due to the separation of each individual path in the cache.