- [Instructor] So far
in our discussion of route redistribution
we've been focused on IP version four routes.
However, we've got a couple of considerations
when it comes to redistributing IP version six routes.
The first consideration that deals with
the redistribution of connected networks.
For example consider a router
that's running a writing protocol maybe an OSPF
and we have several interfaces on that router
that are participating in OSPF.
And on that same router we're running
another routing protocol
may be as EIGRP
and we're doing that mutual route redistribution
between those two different autonomous systems,
those two different routing protocols,
well, here's what might be surprising,
if we're doing a route redistribution on that router,
the IP version four networks
associated with that router's interfaces
that are participating in OSPF
those networks for those connected interfaces
those will be redistributed into EIGRP,
however that's not the behavior we have
with IP version six networks.
Specifically with IP version six networks,
we have to give an extra parameter
in our route redistribution configuration to explicitly say,
"Hey we want to redistribute connected networks
"that are participating in this surrounding protocol."
Otherwise those IP version six networks associated
with directly connected interfaces,
they're not going to be redistributed.
And here's the logic behind that.
It stems from the understanding
that in order to redistribute a route
a route has to appear in a router's IP routing table.
Of course, when we look at a router's IP routing table
and we see directly connected networks
they don't show up as being learned by OSPs for EIGRP.
They show up as being learned because they're connected
and route redistribution with IP version four
understands that the network is directly connected
but it's also participating in this routing process
so we're going to go ahead and redistribute it.
That's part of that routing process.
However IP version six route redistribution
does not make that assumption.
So if we're redistributing IP version six networks
from one routing protocol into another,
those networks need to show up
in a routers IPV six routing table
along with the indication that they were learned
via that writing protocol.
In other words they weren't learned
because they were directly connected.
However, we can add a parameter to our redistribute command
that calls those directly connected IPV six networks
that are participating in a redistributed protocol
to also be redistributed.
And we'll go out to some live gear in a few moments
and I'll show you how that works.
But the other consideration we have
with IP version six route redistribution
deals with the subnets option.
You might remember in a previous video,
we discussed a potential issue that we might have when
redistributing into OSPF.
And this depends on your Cisco IOS version,
but the issue was related to subnets.
You see, by default on some versions
of Cisco IOS, OSPF only redistributes classful networks
into OSPF, unless we add the subnets parameter
to the redistribute command
and the addition of that parameter
allowed the redistribution of networks into OSPF
even if they were not using a classful mask,
but please keep in mind
that some recent versions of Cisco IOS
even though the redistribute command
still needs the subnets parameter
it's entered for us automatically.
So just check to see what
your particular Cisco IOS version does.
However, there is no subnets parameter
with IPv6 route redistribution
and the reason is IPv6 has no concept of subnets.
Now let's go out to a live interface
and see how we can configure IPv6 route redistribution.
Well in this topology router R2 is doing
a mutual route redistribution
of IP version six routes between OSPF and EIGRP.
Let's do a show IPv6 route
just to see what routes we know about.
And we have six different IP version six networks
in this topology.
And let's see, I think we know about all of them.
We've learned about this one from OSPF,
this one from OSPF.
This one is directly connected.
Here's one we've learned via EIGRP.
And here's another one we've learned via EIGRP.
However, right now we're not doing any redistribution.
Let's prove that
let's go over to R1 and do a show IPv6 route command.
And here, all we know about are directly connected networks.
We haven't learned anything.
So let's set up mutual route redistribution,
keeping in mind that extra consideration that
when we're redistributing into a routing protocol
we're not going to redistribute by default
those networks that belong to the routing protocol
being redistributed that are directly connected.
We have to give an extra parameter
and I'll show you how to do that.
Other than that,
it's really not much different
from our previous configurations.
Let's go into global configuration mode
and let's say IPv6 router,
EIGRP autonomous system number one,
and let's create a redistribute statement.
We'll say redistribute, OSPF process ID one.
Let's apply the metric as part of this redistribute command.
I'll say 1 million K.
In other words, one gig for the bandwidth
we'll say we have a delay of two tens of microseconds.
So 20 microseconds.
we'll say that we are completely reliable,
we are minimally loaded, and we've got an MTU of 1500 bytes.
Now notice that we can issue
the include hyphen connected parameter.
That's the perimeter that I was telling you about
that we need to add on
when we're redistributing IP version six networks.
So let's say include hyphen connected.
Let's do the same thing for the OSPF writing process.
I'll say IPv6 router or SPF process ID one.
We want to redistribute EIGRP autonomous system one.
And if I give some context sensitive help,
you'll see there is no subnets parameter here,
because like we said IP version six
doesn't have the concept of subnets.
However we do need to do this include connected.
So let's say include-connected.
And I think we're done.
Just to confirm this work.
So let's visit R1 and R3
and make sure that they know about all six networks
in this topology.
Let's go back to R1 and reissue the show IPv6 route command
and we do know about three networks
to which were directly attached.
And we know about three networks that were redistributed
into OSPF.
Notice the OE2 that means, OSPF external type two.
Remember the type two as opposed to type one,
type two does not change the metric assigned
at the point of redistribution
as a route travels through multiple other routers.
That's the reason I was saying in a previous video,
I'm sort of a fan of type one,
but here's the default it's type two.
Let's make sure that R3
also knows how to get to all these routes.
Let's do a show IPv6 route.
Here we've learned three networks,
via EIGRP and the EX is telling us that
it's an EIGRP external route.
In fact we can see the one 70 right there,
it has a different administrative distance
if it's an external route,
it would have an administrative distance of 90
if it was internal,
but it's got a 170 because it's external.
And we know about our three directly connected routes.
So now all of our routers and our topology
know about all the routes.
We've successfully performed IP version six
mutual route redistribution.