Each of these other network entries in the routing table has an accumulated distance vector to
show how far away that network is in the given direction.
When the topology in a distance vector protocol internetwork changes, routing table updates must
occur. As with the network discovery process, topology change updates proceed step by step from
router to router.
Distance vector algorithms call for each router to send its entire routing table to each of its adjacent
or directly connected neighbors. Distance vector routing tables include information about the total
path cost (de?¬?ned by its metric) and the logical address of the ?¬?rst router on the path to each
network it knows about.
When a router receives an update from a neighboring router, it compares the update to its own
routing table. The router adds the cost of reaching the neighboring router to the path cost reported
by the neighbor to establish the new metric. If the router learns about a better route (smaller total
metric) to a network from its neighbor, the router updates its own routing table.
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Routing Table
10.1.
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