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Chapter 5
IP Routing
Permanent If the interface is shut down or the router cannot communi-
cate to the next-hop router, the route is automatically discarded from the
routing table. Choosing the permanent option keeps the entry in the rout-
ing table no matter what happens.
To be able to understand how static routes work, I'll demonstrate the con-
figuration on my sample internetwork, as shown previously in Figure 5.2.
2621A
Each routing table automatically includes directly connected networks. To
be able to route to all networks in the internetwork, the routing table must
include information that defines where these other networks are located and
how to get there.
The 2621A router is connected only to network 172.16.10.0. For the
2621A router to be able to route to all networks, the following networks
must be configured in the routing table:
172.16.20.0
172.16.30.0
172.16.40.0
172.16.50.0
The following router output shows the configuration of static routes on
the 2621A router and the routing table after the configuration. For the
2621A router to find the remote networks, an entry is placed in the rout-
ing table describing the network, the mask, and where to send the packets.
Notice that each static route sends the packets to 172.16.10.2, which is
the 2621A router's next hop.
2621A(config)#ip route 172.16.20.0 255.255.255.0
172.16.10.2
2621A(config)#ip route 172.16.30.0 255.255.255.0
172.16.10.2
2621A(config)#ip route 172.16.40.0 255.255.255.0
172.16.10.2
2621A(config)#ip route 172.16.50.0 255.255.255.0
172.16.10.2
After the router is configured, you can type show running-config and
show
ip route to see the static routes. Remember that if the routes don't
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