Link Reversal Routing 1 Full Link Reversal Algorithm

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Link Reversal Routing 1

Link Reversal Routing 1

“Full” Link Reversal Algorithm g The algorithm determines routes to one specific destination g

“Full” Link Reversal Algorithm g The algorithm determines routes to one specific destination g When there are multiple destination, one instance of the algorithm is used for each destination separately g These slides focus on one instance of the algorithm g In the example that follows, D is the chosen destination 2

Link Reversal Algorithm A C B E D F G Links are bi-directional But

Link Reversal Algorithm A C B E D F G Links are bi-directional But algorithm imposes logical directions on them Maintain a directed acyclic graph (DAG) for each destination, with the destination being the only sink This DAG is for destination node D 3

Link Reversal Algorithm A B F C E G Link (G, D) broke D

Link Reversal Algorithm A B F C E G Link (G, D) broke D Any node, other than the destination, that has no outgoing links reverses all its incoming links. 4 Node G has no outgoing links

Link Reversal Algorithm A B F C E G Represents a link that was

Link Reversal Algorithm A B F C E G Represents a link that was reversed recently D Now nodes E and F have no outgoing links 5

Link Reversal Algorithm A B F C E G Represents a link that was

Link Reversal Algorithm A B F C E G Represents a link that was reversed recently D Now nodes B and G have no outgoing links 6

Link Reversal Algorithm A B F C E G Represents a link that was

Link Reversal Algorithm A B F C E G Represents a link that was reversed recently D Now nodes A and F have no outgoing links 7

Link Reversal Algorithm A B F C E G Represents a link that was

Link Reversal Algorithm A B F C E G Represents a link that was reversed recently D Now all nodes (other than destination D) have an outgoing link 8

Link Reversal Algorithm A B F C E G D DAG has been restored

Link Reversal Algorithm A B F C E G D DAG has been restored with only the destination as a sink 9