D-Link DGS-6600-48TS Configuration Guide - Page 277

Volume 4-Layer 3 Configurations / Chapter 28-Open Shortest Path First Version 3 (OSPFv3) Chapter Overview Figure 28-4 The link state database (LSDB) is the most important component of OSPF. The LSDB is a data structure consisting of LSAs exchanged in the AS. The link state information is structured to allow the building of a tree whose branches and leaves represent the shortest paths to all routes within the AS. Each router builds such a tree from its point of view. Most commonly, the routers use the algorithm developed by Dijkstra to build this tree of shortest paths (SPF tree). First, the router builds the intra-area tree to all destinations within its own area. Inter-area and external routes are then attached to the branch representing an ABR or ASBR. At the end, each route within the tree is added to one of four sections of the OSPF routing table: the intra-area routes, inter-area routes, external-1 routes, and finally, external-2 routes. The next hop is always the link-local address of first router in the shortest path to the route. The following sections describe each of these components, starting with the contents of the LSDB. DGS-6600 Configuration Guide 277