How SPF Works
In a link-state routing protocol, each router knows about all other routers in a network and the links that connect these routers. In OSPF, this information is encoded as Link-State Advertisements (LSAs); in IS-IS, this information is Link-State Packets (LSPs). This chapter does not discuss the differences between these two protocols. See Appendix B,“CCO and Other Resources,” for more information. Because the acronym LSP also stands for Label-Switched Path, the unit of information a router uses to flood its connectivity information will be called an LSA. Remember that IS-IS works much the same way that OSPF does.
As soon as a router knows about all other routers and links, it runs the Dijkstra Shortest Path First algorithm (named ...
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