CSE 123 Lecture 8: L8 10/15/18
15 Oct 2018
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All nodes think they"re the root initially . Every bridge has a # when they"re manufactured (globally unique!) Each bridge sends periodic configuration messages (speaks the same protocol) Rebroadcast new config to ports for which we"re best . Select port with lowest cost (bridge #) to root as root port . To break ties, bridge w/ smaller address is better. Join the tree in the direction that puts you closer to the root! Recruit other bridges by advertising your ports where you are best! You are closer to the root than any of the messages you"ve been receiving on other ports! Don"t bother sending config to lans w/ better options. Adds 1 to distance, send new configs on ports that haven"t told us about a shorter path to the root. You don"t forward any frames on a port on which you are not best (logically turned. If not refreshed for maxage seconds then delete root and recalculate spanning tree.
