Hi Guys,
I'm labbing up some OSPF LSA scenarios and I think I've confused myself more than anything else but would appreciate some clarification. LSA Type 1 - Sent from all OSPF Routers in an Area, advertising the links/networks it has. LSA Type 2 - Sent from DR to all OSPF routers telling everyone who's in it's area. So within an LSA Type 1 packet, amongst everything else, there's the Link State ID which appears to be the RID, there's the ADV Router which appears to be the RID and then the types of networks it has -stub, transit and their subnets. There's nothing that I can see that says "This is the actual IP you can reach me at" In an LSA Type 2, it seems to just contain the RID's of all other OSPF routers on the segment. The issues I seem to have is how does the SPF algorithm derive the next hop for a network. The packet captures I've taken for LSA Types 1 & 2 all deal in RID. Does it take it from the neighbour table which does contain actual interface ip of its neighbour?? When I debug ospf spf, I see where it installs the route with the next hop but I'm not sure where it actually gets the next hop info. Thanks in advance, Neil _______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com
