This is one of multiple IP version 6 troubleshooting videos in this and network.
We've been told that a rotten one on the left cannot ping the loopback of a three.
The Rotto on the right.
So let's verify that now because this is IP version 6 rather than IP version 4.
Notice no IP version 4 rats exist in the writing table.
We need to do all our testing using IP version 6 something of ping the loopback of router 3 we get a
failure.
We are not able to paying the loopback of Rodda 3 let's do a trace route and see how far we get a case
so what do you think about to the south.
Put what's going on here.
Notice we told that the destination was not found inside the max hop count diameter.
So let's do that again.
Notice what's happening.
So where is the traffic going.
Now this is a good example of a routing loop.
So if we scroll up.
Notice what's happening.
Traffic goes to rodded too.
Then it goes to write a one then to write it to then to write a one back to route it to back to route
of one and so forth and so on.
So we have a loop taking place here.
So let's have a look at the writing table show IPV 6 Robert Rotto one has a default route to 2001 call
on one column column two which is routed to Hence the traffic is being sent to route it to.
But on route to show IPV 6 route can you see the problem here.
Post the video if you need to but see if you can find the problem.
OK so we have a static default route to Rato 3.
That looks OK.
There's a static route to the loop back of road one that also looks OK.
He has a static route to the loop back of Route 3 but that looks wrong.
Notice where it's pointing it's saying to get to the loop back of router 3.
We need to go via route 1.
So that's definitely not right and it's kind of redundant because we have this default route in the
writing table.
So show run piping clewed route.
We need to get rid of this route and either fix the next hop or simply remove it and rely on the default
route here.
So Ken wrote a one paying the loop back up to three.
OK the pings are still failing it's trace to that address the packet gets sent to brought it to you
but then goes nowhere else so it doesn't look like it gets any further based on that output.
So Ken wrote it to paying the loopback of wrote a three
yes it can Sarada to Pinga Lupica wrote a three but rather one can ping the Lubeck of rorted three on
a three let's do it.
De-bug and check if the traffic is actually getting to rodders 3 from Rotto 1 and we can see that it
is.
So we can see that the pings are arriving at rodders 3 but it looks like the reply is not getting back
to route 1.
So router 3 received an echo request from 2001 color on one color in column one which is Route 1 destination
is the loop back of Route 3.
So the etca replace S..
But it's not getting back again.
So let's turn off debugging and that's to a debug IPV 6 packet.
Now in the real world you need to be very careful doing this.
I'm going to send a single packet.
And let's see what happens.
Again be very careful doing this in the real world.
You'll get a lot of output even in the small network.
If we don't turn off debugging we might get a lot of output on the console.
So the Debug.
I sent a single pain from wrote a one to registry.
We've got a destination look up for that.
The Rodda sees that as a local network connected to the loopback So that looks good.
But notice here IPV six forward no router to destination 2001 Cullinan colon colon one source is the
loopback of Rodda 3 destination is the gigabit 00 interface of router 1.
And we told that there is no valid route.
So it doesn't look like a router 3 knows how to get back to Rotto one.
So show IPV six rocked.
Is there a raft in the writing table to get back to Router one.
And the answer is no we have this static route which would allow router 3 to ping the loopback of wrote
a one but it can't ping.
Two thousand and one.
So what we need to do is add a steady crotched to Thousand and One cold on one cool and cold and zero
slushed 64 and send that to Rodda to.
Now let's do the ping again.
Notice the pings succeeded.
And without using the repeat command the pings now succeed.
So we can get to the loopback of rota 3 and we can get to the physical interface of rodders free.
So be careful with pings.
This applies to both IP version 4 and IP version 6 just because I can send traffic to you doesn't mean
that you know how to send traffic back to me.
Both sides need rots in the writing table to enable two way communication.
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