CSE 123 Lecture Notes - Lecture 14: Routing Protocol, Open Shortest Path First
29 Oct 2018
School
Department
Course
Professor
Document Summary
Ttl in every lsp! (so packets don"t flood routers) When ttl = 0, purge the lsp and flood network w/ lsp of ttl = 0. Configuration change like an updated link metric. Until routing protocol converges, strange things happen! Say a link (between b and c breaks) If b keeps forwarding to c, then it"s what"s called a black hole . B and c have to detect that their link failed. Detection delay - a node does not detect a failed link immediately. Packets that are lost are failed hellos . Detection latency - when to figure out it"s sending hellos. Have to compute dijkstra (routing forwarding) Lost packets due to black holes and loops (ttl will expire!) How many routers should detect link failure? (at least 2) Don"t want to jump on the lsp immediately! Too fast is too glitchy (false alarms!) Almost all isps and large orgs use some flavor of link-state inside their domains!
