The routing table is created over time as updates are sent by the Routing Protocol. The example below shows a simulation of how a routing protocol would converge.
Each Router has it’s directly connected routes associated with its interfaces, white background with cost = direct. These networks were configured by network administrators like you. As is the routing protocol that will update the routers. After 30 seconds (sped up to 5 seconds in animation), each router will send an update about all the routes it has in its routing table.
The update is just a listing of the subnets it has learned. This list is processed by the receiving routers and updated with hop count/ cost and the ip address of the router that sent them.
At each increment of 30 seconds, more routes are listed to neighbors. RtrC converges with all routes in 1 minute. RtrB, D, and E join it in 1:30 minutes and finally, RtrA and F in 2 minutes. The hop count/cost increments based on the number or routers that need to crossed. The Administrative Distance (AD) is a believability of the updates. Each routing protocols has a believability index, this allows routers to determine which updates are better if the updates come from two different routing protocols for the same subnet.
RtrC, D, and E have two paths of equal cost that are bolded.
The final routing table can be reviewed below.
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