TABLE OF CONTENTS A mobile node may not know the address of its home agent when it wants to send a Binding Update message for home registration. For example, if a mobile node reboots on a foreign network, there is no information about the home agent unless such information is pre-configured.
The Dynamic Home Agent Address Discovery mechanism is used to get the address information of home agents when a mobile node is in a foreign network. A mobile node sends a Dynamic Home Agent Address Discovery request message when it needs to know the address of its home agent. The source address of the message is a care-of address of a mobile node and the destination address of the message is a home agent anycast address which can be computed from the home prefix. This message does not contain a Home Address option, since this message may be sent before the first home registration is completed. A mobile node cannot use its home address before home registration is completed.
On the home network, home agents maintain the list of global addresses of all home agents on the home network by listening to each other's Router Advertisement messages. As described in Section 5.3.6, a home agent advertises its global address with a modified Prefix Information option. Figure 5-45 shows the concept.
Every home agent has a special anycast address called a home agent anycast address which is...
