Wednesday, November 11, 2009

OSPF CCNA Lab Review


I spent the better part of my morning reviewing OSPF CCNA theories and how this link-state protocol works. It was good to get my head wrapped around LSA's and LSDB's and how each router calculates it's own routing table using SPF Algorithm. A Link-State Data Base (LSDB) is basically a map that each router uses to plan the best route to reach every other router in its inter-network. Routers use OSPF to find out what information it's neighboring router has such as it's IP, subnet, and RID (Router I.D.) along with rather it should even communicate with its neighbors. Routers sends multicast Link-State Advertisments (LSA's) to the 224.0.0.5 address out all of it's interfaces in hopes that one of it's neighboring routers will respond back. I created a simple OSPF lab today and tomorrow I will hopefully create a lab consisting of Priorities and OSPF interface cost associations to pre-determine a path the router should take to reach certain networks.

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