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Intro to the Contralized (Link State) Routing Algorithm

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• Preliminaries to the Centralized Routing Algorithm
  • Recall: centralized route computation algorithm

    Every node sends its link cost information to all nodes in the network.

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  • Problem:

    How does a nodes send its link cost information to other nodes ???

    Answer:

    The node uses it's routing table !!!!         However: The routing table has not been computed yet !!!!

    This is a Chicken and Egg dillema ....

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• Important observation
  • Important fact:

    The (centralized) link state route construction algorithm cannot use routing table information to send link cost information to other nodes in the network !!!!

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• Sending information to every node: Broadcasting
  • Broadcasting:

    Broadcasting = sending a message to all node in the network

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  • Some facts on broadcasting:

    Broadcasting is easy in networks that have broadcast capability Example: Ethernet, Token Ring, etc. etc Broadcasting is an inefficient operation in non-broadcast (point-to-point) networks It is even more inefficient when you cannot use routing tables...