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This is one of multiple IP version six troubleshooting videos in this topology.

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We've been told that router one on the left is not able to ping the loopback of router three on the

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right.

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So let's verify that ping 2001 face three.

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We're getting an unreachable message.

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So let's have a look at the writing table.

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Show IPV six route.

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We've got a default route to router two.

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So when we use a trace route to that address, notice the traffic gets to router two but gets no further.

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So we're getting unreachable messages.

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Let's have a look at writer to.

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Ping 2001 face three.

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Notice the output?

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No.

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A valid route for destination.

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So let's have a look at the routing table.

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So show IPv6 route.

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Do you see a route in the routing table for the loopback of router three?

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This is a connected and local rut.

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Connected local.

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There is no static route for the loopback of router three.

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This is a static route for the loopback over out of one.

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So show run pipe include root.

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So here's the static route to router one.

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Here's a default route pointing to route of three.

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So what do you think is the problem here?

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We have a steady grant configured, but it's not showing up in the routing table.

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What's the problem?

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Let's have a look at our interfaces.

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So show IPV six interface brief.

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Can you see the problem in the output?

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Notice Gigabyte zero one is administratively down.

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That's a problem.

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So interface gigabit.

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Zero one no shut show IPV six.

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Root.

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Suddenly we see.

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The default route in the IP routing table.

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And if we're paying 2001 face three, the ping succeeds on this side.

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When we do the trace route notice it succeeds.

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So rather one is able to ping the loopback of router three.

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Now don't forget IPV six is a layer three protocol.

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In the same way that IP version four is a layer three protocol.

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Layer three protocols rely on layer two protocols and layer one protocols.

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So show CDP neighbors would allow us to verify and check.

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Layer one and layer two.

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And we could also look at the interfaces on the router by using commands such as show interface gigabit

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zero one.

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That would allow us to check if the interface is up.

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Up.

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Or show IPV six interface gigabit.

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Zero one.

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This would show us whether the interface is up and also allow us to verify IP addresses configured on

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that interface.

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One of the hardest parts with troubleshooting networks is to narrow down where the problem is in the

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network.

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It could be something as simple as an interface shut down or a cable that's unplugged or a damaged cable.

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Higher layer protocols rely on the lower layer protocols, so you need to use the OCI model in your

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troubleshooting to help you find where the problem is.

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This wasn't a layer three issue.

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In other words, it's not a routing issue or an IP version six issue.

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It was a physical issue.

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The interface on the rudder was shut down.

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I hope you enjoyed this video.

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If it was of benefit to you, please like it and please subscribe to my YouTube channel.

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I wish you all the very best.