ICND1 100-105

ICND1 100-105

Static Routing with IPv6

We have a few different routing types here: static routing, Routing Information Protocol Next Generation, or RIPng, Enhanced Interior Gateway Routing Protocol, or EIGRP for IPv6, Open Shortest Path First version 3, or OSPFv3. What version did we see for v4? We saw OSPFv2. We mentioned that, in fact, because we know you were going to see it here and then Border Gateway Protocol, or BGP, multiprotocol BGP, which really means it's the current new flavor and it is indifferent to what it advertises. It just says, okay, I'll advertise for you. There is even another. Do you remember the other link-state routing protocol? It was Intermediate System to Intermediate System, or IS-IS. It's extremely effective at advertising Internet Protocol version 6, or IPv6 routes. But, which two of these are we going to focus on?

We're going to focus on static routing and OSPF version 3.

Static routing

There should be no surprises here with our static routing configuration. The only real difference is that we are configuring the static routing for IP version 6, so our command will start out differently.

IPv6 Static Routing

Let's look at it from Headquarters, or HQs perspective right now. IPv6. With IP version 4, we did IP route, but no, now it's IPv6 route. What do we put in next? Well the destination network we're trying to point to, right?

HQ(config)#ipv6 route 2001:DB8:A01::/48 Gi0/1 2001:DB8:D1A5:C900::1

Yeah, and I really love this. What is the prefix of this? You see that subnet mask, we call that, you know, the prefix /48. Do you remember what gets handed to a site? It's a /48. So that's a site prefix. So if you're pointing headquarters to a branch, you really would be using a /48, unless we knew better, so it's very realistic. We then have the exit interface and then the next hop IP address that we would point to. So it looks really nasty, doesn't it? I mean, it even looks nasty to me. But we see the network, the direction, the next hop IP address, it's a v6 address, but it's still next hop IP address, so it looks really good. So that helps headquarters get over to branch and remember how we taught you that static routes are unidirectional and that static routes only help the local router. So traffic is bi-directional, so we're able to get now our routes from headquarters to branch, but branch is going to use headquarters as the upstream router to get to all other networks. How do I account for that?

I would use a default static route to get there. Let's configure that for IP version 6.

Branch(config)#ipv6 route ::/0 Gi0/1 2001:DB8:D1A5:C900::2

Looks funky, it really does, but that is our default route for IPv6. Why? It's truncated, that's all. We could type in if we wanted to 0000:0000 etc, etc. I won't bore you with that, but we know how to truncate now. We covered that and that's what it boils down to ::/0 and then the exit interface and the next hop IP address. So all traffic that is destined for outside of the branch site, we're sending it to HQ.

So, this is a really solid config as we mentioned. It's well done and it's a config you want to be familiar with.

We can verify the static routes we created by looking at our routing table. But we have a different routing table to look at. We're not looking at the IPv4 routing table anymore, no. We're looking at the IPv6 routing table, show ipv6 route. We can still tack on key words like we do with our IP version 4 routing table, such as static or EIGRP or OSPF.

HQ#show ipv6 route static
IPv6 Routing Table - default - 4 entries
Codes: C - Connected, L - Local, S - Static, U - Per-user Static route
       B - BGP, R - RIP, I1 - ISIS L1, I2 - ISIS L2
       IA - ISIS interarea, IS - ISIS summary, D - EIGRP, EX - EIGRP external
       ND - Neighbor Discovery
       O - OSPF Intra, OI - OSPF Inter, OE1 - OSPF ext 1, OE2 - OSPF ext 2
       ON1 - OSPF NSSA ext 1, ON2 - OSPF NSSA ext 2
S   2001:DB8:A01::/48 [1/0]
     via 2001:DB8:D1A5:C900::1, GigabitEthernet0/1

But here let's just look at the static entries and what do we see, S for static and then the destination network and then we still have our brackets, our parentheses, administrative distance, and metric and then how we get there, via which next hop IP address and which local interface are we going to use. So no surprises here. We read it the same way; we just access it using a different command.

But there's one thing that jumps out when it comes to the static default route and that is with IP version 6, we don't get the nice little asterisks like we do with IPv4, it's missing. So you might be looking for that asterisks with the static default route, but it's not there with IPv6.

Branch#show ipv6 route static
IPv6 Routing Table - default - 4 entries
Codes: C - Connected, L - Local, S - Static, U - Per-user Static route
       B - BGP, R - RIP, I1 - ISIS L1, I2 - ISIS L2
       IA - ISIS interarea, IS - ISIS summary, D - EIGRP, EX - EIGRP external
       ND - Neighbor Discovery
       O - OSPF Intra, OI - OSPF Inter, OE1 - OSPF ext 1, OE2 - OSPF ext 2
       ON1 - OSPF NSSA ext 1, ON2 - OSPF NSSA ext 2
S   ::/0 [1/0]
     via 2001:DB8:D1A5:C900::2, GigabitEthernet0/1

And even I'm looking for it. I'm looking for it and I am like, S, well where is the default static route? Oh we look to the next column, double colon, which is unspecified. You pair that up with /0, that's really unspecified. That says any IPv6 address, go here and again we have those brackets, administrative distance followed by the metric, metric is 0 for static routes, but the administrative distance is 1 just like we saw in the previous page and then the next hop IP address and the exit interface and then we go out. Remember, next hop IP address is so that we can Address Resolution Protocol, or ARP, for that. Ooh, but that's for v4, that's an old concept. But what is it really? It's neighbor solicitation. So we have to do a neighbour solicitation for that IP address so we can resolve it to a Media Access Control, or MAC, address.

Just because it is in the routing table, doesn't mean you have connectivity. Always, always ping to verify you have connectivity after creating static routes. Ping and then the destination address. Don't forget about pinging!!