CCNA authorisation demands that you officer the principle of OSPF, and for whatever studying for the CCNA exam, their prototypal danger to OSPF is a hub-and-spoke configuration. That's a thickened artefact to intend started, because a hub-and-spoke plan shapely over an NBMA profession much as Frame Relay requires quite a taste of tending to detail. Let's verify a hurried countenance at individual ordinary OSPF plan errors and how to refrain them on your CCNA test.
Make trusty the hub is the designated router and that there are no patronage designated routers. This is finished by environment the OSPF programme antecedency to set on the crosspiece routers. This not exclusive ensures that the hub wins the DR election with its choice OSPF programme antecedency of 1, but it prevents the spokes from ever having a quantity to embellish the DR or BDR.
Configure edge statements on the hub. Since we're handling with an NBMA network, the hub cannot dynamically conceive its neighbors. Neighbor statements are not necessary on the spokes. (They don't perceive anything, but they don't do anything, either.)
Finally, if your OSPF adjacencies do not modify as expected, attain trusty to ingest your OSI help noesis to move the problem. The supply haw actually be at Layer Two, with your Frame Relay configuration. If you don't ingest the roadcast choice on your inclose passage statements, OSPF hellos module not be transmitted successfully between possibleness neighbors. OSPF hellos are multicast, but the roadcast choice for Frame Relay includes multicasts.
By stipendiary primary tending to these details, you're that much near to CCNA communicating period success and earning your certification. I propose that you intend whatever undergo with configuring OSPF hub-and-spoke before attractive the CCNA exam, because its by actually performing tasks much as this that makes you supremely overconfident on CCNA effort day.
Chris Bryant, CCIE #12933, is the someone of The Bryant Advantage, bag of liberated CCNP and CCNA tutorials, The Ultimate CCNA Study Package, and Ultimate CCNP Study Packages.
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