CCNA6-7

368 Chapter 6  IP Routing
This was a pretty long configuration because I configured two paths to each network.
By looking at the routing table, you can see that the R1 router now understands how to find
each network:
R1(config)#do show ip route
10.0.0.0/24 is subnetted, 12 subnets
S 10.1.11.0 [150/0] via 10.1.3.1
S 10.1.10.0 [150/0] via 10.1.3.1
S 10.1.9.0 [150/0] via 10.1.3.1
S 10.1.8.0 [150/0] via 10.1.3.1
S 10.1.12.0 [150/0] via 10.1.3.1
C 10.1.3.0 is directly connected, Serial0/0/1
C 10.1.2.0 is directly connected, Serial0/0/0
S 10.1.1.0 [150/0] via 10.1.2.1
C 10.1.7.0 is directly connected, FastEthernet0/1
C 10.1.6.0 is directly connected, FastEthernet0/0
S 10.1.5.0 [150/0] via 10.1.2.1
S 10.1.4.0 [150/0] via 10.1.2.1
The R1 router now has a complete routing table. As soon as the other routers in the internetwork
have all the networks in their routing table, R1 will be able to communicate with all
remote networks.
Remember, the route with the higher administrative distance will not show
up in the routing table unless the route with the lower administrative distance
goes away.
R2
The R2 router is directly connected to three networks 10.1.4.0, 10.1.8.0, and 10.1.9.0, so
these routes need to be added:
 10.1.1.0
 10.1.2.0
 10.1.3.0
 10.1.5.0
 10.1.6.0
 10.1.7.0
 10.1.10.0
Configuring IP Routing in Our Network 369
 10.1.11.0
 10.1.12.0
Here’s the configuration for the R2 router:
R2(config)#ip route 10.1.1.0 255.255.255.0 10.1.4.1 150
R2(config)#ip route 10.1.2.0 255.255.255.0 10.1.4.1 150
R2(config)#ip route 10.1.3.0 255.255.255.0 10.1.4.1 150
R2(config)#ip route 10.1.5.0 255.255.255.0 10.1.4.1 150
R2(config)#ip route 10.1.6.0 255.255.255.0 10.1.4.1 150
R2(config)#ip route 10.1.7.0 255.255.255.0 10.1.4.1 150
R2(config)#ip route 10.1.10.0 255.255.255.0 10.1.4.1 150
R2(config)#ip route 10.1.11.0 255.255.255.0 10.1.4.1 150
R2(config)#ip route 10.1.12.0 255.255.255.0 10.1.4.1 150
R2(config)#do show run | begin ip route
ip route 10.1.1.0 255.255.255.0 10.1.4.1 150
ip route 10.1.2.0 255.255.255.0 10.1.4.1 150
ip route 10.1.3.0 255.255.255.0 10.1.4.1 150
ip route 10.1.5.0 255.255.255.0 10.1.4.1 150
ip route 10.1.6.0 255.255.255.0 10.1.4.1 150
ip route 10.1.7.0 255.255.255.0 10.1.4.1 150
ip route 10.1.10.0 255.255.255.0 10.1.4.1 150
ip route 10.1.11.0 255.255.255.0 10.1.4.1 150
ip route 10.1.12.0 255.255.255.0 10.1.4.1 150
The following output shows the routing table on the R2 router:
R2(config)#do show ip route
10.0.0.0/24 is subnetted, 12 subnets
S 10.1.11.0 [150/0] via 10.1.4.1
S 10.1.10.0 [150/0] via 10.1.4.1
C 10.1.9.0 is directly connected, FastEthernet0/0
C 10.1.8.0 is directly connected, Dot11Radio0/3/0
S 10.1.12.0 [150/0] via 10.1.4.1
S 10.1.3.0 [150/0] via 10.1.4.1
S 10.1.2.0 [150/0] via 10.1.4.1
S 10.1.1.0 [150/0] via 10.1.4.1
S 10.1.7.0 [150/0] via 10.1.4.1
S 10.1.6.0 [150/0] via 10.1.4.1
S 10.1.5.0 [150/0] via 10.1.4.1
C 10.1.4.0 is directly connected, Serial0/2/0
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R2 now shows all 12 networks in the internetwork, so it too can now communicate with
all routers and networks (that are configured so far).
R3
The R3 router is directly connected to networks 10.1.5.0, 10.1.10.0, and 10.1.11.0, but we
need to add these routes:
 10.1.1.0
 10.1.2.0
 10.1.3.0
 10.1.4.0
 10.1.6.0
 10.1.7.0
 10.1.8.0
 10.1.9.0
 10.1.12.0
As before, I’m going to use SDM to configure the static routing for the R3 router. The
configuration is pretty simple, and I can use either the next-hop address or the exit interface.
Since I like to type as little as possible, I’m going with the exit interface because it only takes
a mouse click.
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After all our routes are configured, we can see them in the routing screen.
From this screen, it is easy to edit the static routes.
Let’s take a look at the configuration and the routing table uploaded to the router from SDM:
R3#show run | begin ip route
ip route 10.1.1.0 255.255.255.0 Serial0/0/1 150 permanent
ip route 10.1.2.0 255.255.255.0 Serial0/0/1 150 permanent
ip route 10.1.3.0 255.255.255.0 Serial0/0/1 150 permanent
ip route 10.1.4.0 255.255.255.0 Serial0/0/1 150 permanent
ip route 10.1.6.0 255.255.255.0 Serial0/0/1 150 permanent
ip route 10.1.7.0 255.255.255.0 Serial0/0/1 150 permanent
ip route 10.1.8.0 255.255.255.0 Serial0/0/1 150 permanent
ip route 10.1.9.0 255.255.255.0 Serial0/0/1 150 permanent
ip route 10.1.12.0 255.255.255.0 FastEthernet0/1 150 permanent
R3#show ip route
10.0.0.0/24 is subnetted, 12 subnets
C 10.1.11.0 is directly connected, FastEthernet0/1
C 10.1.10.0 is directly connected, FastEthernet0/0
S 10.1.9.0 is directly connected, Serial0/0/1
S 10.1.8.0 is directly connected, Serial0/0/1
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S 10.1.12.0 is directly connected, FastEthernet0/1
S 10.1.3.0 is directly connected, Serial0/0/1
S 10.1.2.0 is directly connected, Serial0/0/1
S 10.1.1.0 is directly connected, Serial0/0/1
S 10.1.7.0 is directly connected, Serial0/0/1
S 10.1.6.0 is directly connected, Serial0/0/1
C 10.1.5.0 is directly connected, Serial0/0/1
S 10.1.4.0 is directly connected, Serial0/0/1
R3#
Looking at the show ip route command output, you can see that the static routes are
listed as directly connected. Strange? Not really, because I used the exit interface instead of the
next-hop address, and functionally, there’s no difference. We really don’t need the permanent
command because all that will do is ensure that the route stays in the routing table even if the
link to that route goes down. I configured the permanent command only because it was easy
to do with SDM (just another mouse click). We’re almost there—just one more router to go:
the 871W.
871W
Now for this router, I’m going to configure something called default routing since the 871W
is configured as a stub. A stub indicates that the wireless network in this design has only one
way out to reach all other networks. I’ll show you the configuration, verify the network in the
next section, then I’ll discuss default routing in detail. Here’s the configuration:
871W(config)#ip route 0.0.0.0 0.0.0.0 10.1.11.1
871W(config)#ip classless
871W(config)#do show ip route
10.0.0.0/24 is subnetted, 2 subnets
C 10.1.11.0 is directly connected, Vlan1
C 10.1.12.0 is directly connected, Dot11Radio0
S* 0.0.0.0/0 [1/0] via 10.1.11.1
871W(config)#
This seems a lot easier, doesn’t it? And it is, but there’s a catch—you can’t do things like this
on all routers, only on stub networks. I could’ve used default routing in routers R1 and R2 as
well, and I didn’t add the 150 to this default route even though I easily could have. I didn’t do
that because it’s really simple to just remove the route when we get to dynamic routing later.
So we’re there—we’ve done it! All the routers have the correct routing table, so all routers
and hosts should be able to communicate without a hitch—for now. But if you add
even one more network or another router to the internetwork, you’ll have to update each
and every router’s routing tables by hand—yikes! This isn’t a problem at all if you’ve got
a small network, but it’s obviously extremely time-consuming if you’re dealing with a
large internetwork!
Configuring IP Routing in Our Network 373
Verifying Your Configuration
We’re not done yet—once all the routers’ routing tables are configured, they need to be verified.
The best way to do this, besides using the show ip route command, is with the Ping program.
I’ll start by pinging from the 1242AP to the 871W router.
Here’s the output:
871W#ping 10.1.1.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.1.1.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/4 ms
From router 871W, a ping to HostA, B, C, and D will also test for good IP connectivity.
Here’s the router output:
871W#ping 10.1.6.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.1.6.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 4/6/12 ms
871W#ping 10.1.7.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.1.7.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 4/4/4 ms
871W#ping 10.1.9.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.1.9.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 4/4/4 ms
871W#ping 10.1.10.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.1.10.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5)
Also, we can trace from the 871W router to see the hops the packet takes to get to HostA:
871W#trace 10.1.6.2
Type escape sequence to abort.
Tracing the route to 10.1.6.2
1 10.1.11.1 0 msec 0 msec 0 msec
2 10.1.5.1 4 msec 0 msec 4 msec