CCNA #037 OSPF Troubleshooting - can you find the issue? CCNA Exam 200-125 troubleshooting

Key Takeaways

[Music] this is one of multiple OSPF troubleshooting videos in this scenario we be told that rather one is not able to pin right a fault let's test that can write a one thing the loopback of rata for answer is no show IP route we are receiving OSPF wraps so we are receiving a rut for the loopback of routed to we're receiving a route for Network 10120 that we're not receiving other rods show IP ospf neighbor confirms that we have a neighbor relationship too bright or too so as an example we can ping the loopback of router - I'll disable IP domain lookup to make trace route complete quicker and let's see if we can trace to router for the trace in this example will not leave the local router because we don't have a gateway of last resort and we don't have a specific route to equitable 4 so the trace is simply dropped at the local router now what about rotted to show IP ospf neighbour routed to has a neighbor relationship to router one but doesn't have a neighbor relationship to router 3 can write it to ping router 3 yes it can so it doesn't look like it's an IP connectivity problem it looks like it's something else can write a 3 ping routed to yes it can show IP ospf neighbor router 3 has the neighbor relationship to write a 4 but not to write a 2 so we definitely have a problem between rather 2 and right of 3 so I'm write a to show IP ospf interface brief OSPF is enabled on gigabit to 0 0 and gigabit to 0 1 shows CDP neighbors shows us that router 3 is connected to gigabit to 0 1 so if VF is enabled on that interface the local route is a designated router back on router 3 show IP ospf interface brief OSPF is enabled on gigabit 0 0 and gigabit to 0 1 we can see that router 2 is connected to gigabit 0 1 so if F is enabled on this interface and the local router the leaves that it's the designated router so we have two routers on the same segment thinking that they are the designated riders let's have a look at the interface without brief so show IP ospf interface gigabit zero one we can see the IP address of the router the area is area zero rudder ID is this network type is broadcast cost is one there is no backup designated router on this segment we can see the hollow and other timers we can see a lot of other information here what about on this side so show IP ospf interface gigabit to zero one can you spot the problem what's the problem between routed to [Music] and router three here's router two years rather three what's the problem okay look at the timers for OSPF to form neighbor relationships the timers must be the same the hollowed timer on router three is thirty seconds whereas it's ten seconds on routed to data interval on the side is forty the side 120 wait is 40 120 retransmit is five and five also have a look at the neck up type that's a broadcast this is a non broadcast if you want OSPF routers to form a neighbor relationship that primers need to be the same timers can be influenced by the network command Ethernet is a broadcast multi-access environment not a non broadcast environment that would be used for frame relay as an example so we need to set the OSPF Network type to broadcast and notice as soon as I've done that neighbor relationships are formed if you look at the timers notice that timers here are now the same two timers are set the same show IP ospf neighbors we have two neighbor relationships so back on writer one is rather one able to trace to quadruple four yes it is that looks a lot better so we can ping quadruple four is an example that was an OSPF troubleshooting scenario make sure that your timers are the same check your network types in OSPF it's important that the OSPF network types be the same for CCNA there are some weird and wonderful implementations that you can have with OSPF but that's not important for CCNA check your network types check your timers ensure that they the same between routers I hope you enjoyed this video if it was benefit to you please like it and please subscribe to my youtube channel I wish you all the very best [Music]