This is one of multiple IP version six troubleshooting videos in this topology.
We've been told that router one on the left is not able to ping the loopback of router three on the
right.
So let's verify that ping 2001 face three.
We're getting an unreachable message.
So let's have a look at the writing table.
Show IPV six route.
We've got a default route to router two.
So when we use a trace route to that address, notice the traffic gets to router two but gets no further.
So we're getting unreachable messages.
Let's have a look at writer to.
Ping 2001 face three.
Notice the output?
No.
A valid route for destination.
So let's have a look at the routing table.
So show IPv6 route.
Do you see a route in the routing table for the loopback of router three?
This is a connected and local rut.
Connected local.
There is no static route for the loopback of router three.
This is a static route for the loopback over out of one.
So show run pipe include root.
So here's the static route to router one.
Here's a default route pointing to route of three.
So what do you think is the problem here?
We have a steady grant configured, but it's not showing up in the routing table.
What's the problem?
Let's have a look at our interfaces.
So show IPV six interface brief.
Can you see the problem in the output?
Notice Gigabyte zero one is administratively down.
That's a problem.
So interface gigabit.
Zero one no shut show IPV six.
Root.
Suddenly we see.
The default route in the IP routing table.
And if we're paying 2001 face three, the ping succeeds on this side.
When we do the trace route notice it succeeds.
So rather one is able to ping the loopback of router three.
Now don't forget IPV six is a layer three protocol.
In the same way that IP version four is a layer three protocol.
Layer three protocols rely on layer two protocols and layer one protocols.
So show CDP neighbors would allow us to verify and check.
Layer one and layer two.
And we could also look at the interfaces on the router by using commands such as show interface gigabit
zero one.
That would allow us to check if the interface is up.
Up.
Or show IPV six interface gigabit.
Zero one.
This would show us whether the interface is up and also allow us to verify IP addresses configured on
that interface.
One of the hardest parts with troubleshooting networks is to narrow down where the problem is in the
network.
It could be something as simple as an interface shut down or a cable that's unplugged or a damaged cable.
Higher layer protocols rely on the lower layer protocols, so you need to use the OCI model in your
troubleshooting to help you find where the problem is.
This wasn't a layer three issue.
In other words, it's not a routing issue or an IP version six issue.
It was a physical issue.
The interface on the rudder was shut down.
I hope you enjoyed this video.
If it was of benefit to you, please like it and please subscribe to my YouTube channel.
I wish you all the very best.