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Mobile IP Technology and Applications

Chapter Description

This chapter highlights the major concepts of IOS Mobile IP configuration in a simple lab topology. It presents in detail the most important concepts in IOS Mobile IP configuration. We start out by using six routers to examine each component individually. Several alternatives requiring fewer routers are presented at the end of the chapter.

Examining the Routing Table

You should also understand what the routing table will look like. All routes controlled by Mobile IP are marked with an M in the routing table. The Home Agent has two kinds of Mobile IP routes in its routing table, home networks and Mobile Nodes. If a home network is configured as a virtual network, it appears in the routing table as an M route; otherwise, it appears as a connected route. For each Mobile Node that has an active binding, you also find a host route in the routing table. As shown in Example 4-12, the Mobile Node route shows the tunnel that is being used as the next hop.

Example 4-12 Routing Table on the Home Agent

HA#show ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B – BGP
    D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area 
    N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
    E1 - OSPF external type 1, E2 - OSPF external type 2
    i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
    ia - IS-IS inter area, * - candidate default, U - per-user static route
    o - ODR, P - periodic downloaded static route
Gateway of last resort is not set
O  192.168.4.0/24 [110/20] via 192.168.1.1, 01:52:00, Ethernet0/0
O  192.168.5.0/24 [110/30] via 192.168.1.1, 01:52:00, Ethernet0/0
O  192.168.6.0/24 [110/30] via 192.168.1.1, 01:52:00, Ethernet0/0
C  192.168.1.0/24 is directly connected, Ethernet0/0
O  192.168.2.0/24 [110/20] via 192.168.1.1, 01:52:00, Ethernet0/0
   192.168.100.0/24 is variably subnetted, 2 subnets, 2 masks
M    192.168.100.10/32 [3/1] via 192.168.6.1, 01:51:55, Tunnel0
M    192.168.100.0/24 is directly connected
O  192.168.3.0/24 [110/20] via 192.168.1.1, 01:52:00, Ethernet0/0

Example 4-13 looks at the routing table of the IS. The point of including the IS in the topology explored in this chapter is to show that only the home network route is redistributed. In Example 4-13, the virtual network appears as a Type 2 external OSPF route.

Example 4-13 Routing Table on the IS

IS>show ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
    D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area 
    N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
    E1 - OSPF external type 1, E2 - OSPF external type 2
    i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
    ia - IS-IS inter area, * - candidate default, U - per-user static route
    o - ODR, P - periodic downloaded static route
Gateway of last resort is not set
C  192.168.4.0/24 is directly connected, Ethernet3/0
O  192.168.5.0/24 [110/20] via 192.168.3.2, 01:58:45, Ethernet2/0
O  192.168.6.0/24 [110/20] via 192.168.4.2, 01:58:45, Ethernet3/0
C  192.168.1.0/24 is directly connected, Ethernet0/0
C  192.168.2.0/24 is directly connected, Ethernet1/0
O E2 192.168.100.0/24 [110/20] via 192.168.1.2, 01:58:45, Ethernet0/0
C  192.168.3.0/24 is directly connected, Ethernet2/0
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