Another thing that i read is this example:
imagine a diamond shape with 4 routers - each at each end + 1 router that goes through the middle ans is connected to only 2 of the router(the ones that at the end of the more wide angles).
so it says that a router A(found at the end of one side of the less wide angles of the diamond) chooses his routes(Successor and FS)to the lan behind router C which is at the other end.so eventually router A chose E as his FS(E is in the middle and is NOT CONNECTED to A) - but how can that be? he has no physical link to it, only through other routers.(if he wants to go through the middle router he has to go over 3 routers(all the other routers basically) and that is not worth the effort because the metric is high).
i know that RIP and IGRP calculate their routes based on adjacent routers but if you think about it - how can anything else be possible?
I hope you understand my question, it is very hard to explain.