ccna 200 301 syllabus meaning english

ccna 200 301 syllabus meaning english.Each router floods LSAs to all its neighbors, and the router stores all received LSAs in a database. neighboring routers then flood received LSAs to all their neighbors until all routers in the same area have received all LSAs. each router keeps a copy of all received LSAs in a local database, called the LSDB (Link-State Database).Each router, based on the local link state database (LSDB), then executes the SPF algorithm to generate an SPF tree with this router as the root of the tree, and based on the SPF tree, calculates the shortest path to each destination network, which is the routing table. The process of link-state routing protocol routing table generation is shown in Figure 8-1-2.Figure 8-1-2 Link-state routing protocol routing table generation process8.1.3 Advantages and Disadvantages of Link State Routing Protocols** Link state routing protocols have several advantages over distance vector routing protocols.. The topology table is constructed: routers running link-state routing protocols exchange LSAs with each other,forming LSDBs, and the SPF algorithm constructs an SPF tree of the network based on the LSDBs.Using the SPF tree, each router can independently determine the shortest path to each destination network. The distance vector routing protocol, on the other hand, only generates its own routing table based on the announcements of neighboring routers. To put it bluntly, link-state routing protocols have a global view, while distance vector routing protocols show small farmer awareness.. Fast convergence: when a router running a link-state routing protocol receives an LSA, the router immediately floods that LSA to all ports except the receiving port, and then this router performs the SPF algorithm to update the local routing table. In contrast, when a router running a distance vector routing protocol receives a routing table from a neighboring router, it updates the local routing table first and then sends the new routing table out. None of the distance vector routing protocols mentioned here include EIGRP, which is an advanced distance vector routing protocol with a faster convergence rate.. Event-driven updates: routers running link-state routing protocols send updates when a topology change is detected. While routers with distance vector routing protocols are updated periodically. here too EIGRPO is not included Here is a special point to note that routers executing OSPF flood LSAs every 30 minutes,called link state refresh, which is mainly used as an aging mechanism for LSAs. When LSA notices reside in the router's link state database, their aging time is increased, and if these LSA notices reach the maximum aging time (1 hour), then they will be removed from the OSPF domain. So to have a mechanism to prevent normal LSAs from being cleared when they reach their aging time, every 30 minutes the router that originated this LSA announcement will flood a new copy of this LSA with its sequence number plus 1 and the aging time set to 0. The reader knows that having such a 30 minutes is fine, but do not make the mistake of interpreting OSPF as a periodic update.238Chapter 8 OSPF*** I08---------------------------------------------------------------------------------------------------------------------------------- ------M ____