HP-UX Mobile IPv4 A.03.01 Administrator's Guide
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Chapter 3
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Examples
This section provides examples of Home Agent and Foreign Agent assignments.
Home Agents
To use Mobile IPv4, you must configure at least one Home Agent on each subnet (or
network if you are not using subnets) that will host Mobile Nodes. In other words, you
must have one Home Agent with the same network address as the network address that
you assign to the Mobile Nodes.
For example, you may have three Mobile Nodes with the following IP addresses:
• 15.1.1.20
• 15.1.1.21
• 15.1.1.22
The topology uses the subnet mask 255.255.255.0, so the three Mobile Nodes all have the
network address 15.1.1 (in other words, they all belong to the subnet 15.1.1).
On the same 15.1.1 subnet, you must configure at least one node to be the Home Agent.
For example, you could configure node 15.1.1.50 to be the Home Agent for these nodes.
Refer to Figure 3-1, “Home Agent and Foreign Agent.”
Figure 3-1 Home Agent and Foreign Agent
Foreign Agents
If you are not using Co-located Care-of Addresses, you will need at least one Foreign
Agent on each subnet (or network) that the Mobile Nodes will visit. The Foreign Agent
will provide a Care-of Address that the Mobile Nodes will use when visiting the foreign
network. The Foreign Agent will receive the packets addressed to the Care-of Address,
and forward them to the appropriate Mobile Node.