Mobile IP Administration Guide


This glossary contains only definitions of new terms found in this book and are not in the Global Glossary. For definitions of other terms, see the Global Glossary at

address pool

A set of addresses designated by the home network administrator for use by mobile nodes that need a home address.

agent advertisement

A message periodically broadcasted by home agents and foreign agents to advertise their presence on any attached link.

agent discovery

The process by which a mobile node determines if it has moved, its current location, and its care-of address on a foreign network.

bidirectional tunnel

A tunnel that can transmit datagrams in both directions.

binding table

A home agent table that associates a home address with a care-of address, including remaining lifetime and time granted.

care-of address

A mobile node's temporary address used as a tunnel exit point when the mobile node is connected to a foreign network.

foreign network

Any network other than the mobile node's Home Network.

Generic Routing Encapsulation (GRE)

An optional form of tunneling that can be supported by home agents, foreign agents, and mobile nodes. GRE enables a packet of any network-layer protocol to be encapsulated within a delivery packet of any other (or same) network-layer protocol.

home address

An IP address assigned for an extended period to a mobile node. The address remains unchanged when the node is attached elsewhere on the Internet or an organization's network.

home network

A network having a network prefix matching that of a mobile node's home address.

IP in IP encapsulation

The Internet-standard protocol for tunneling IPv4 packets within IPv4 packets.


An iterative cryptographic hash function used for message authentication.

Minimal encapsulation

An optional form of IPv4 in IPv4 tunneling that can be supported by home agents, foreign agents, and mobile nodes. Minimal Encapsulation has 8 or 12 less bytes of overhead than does IP in IP Encapsulation.

mobile node

A host or router that can change its point of attachment from one network to another while maintaining all existing communications, using its IP home address.

mobility agent

Either a home agent or a foreign agent.

mobility binding

The association of a home address with a care-of address, along with the remaining lifetime of that association.

mobility security association

A collection of security measures, such as an authentication algorithm, between a pair of nodes, which are applied to Mobile IP protocol messages exchanged between the two nodes.


A host or a router.

Network Access Identifier (NAI)

Used to uniquely identify the mobile node in the format of user@domain.


The process by which a mobile node registers its care-of address with its home agent when it is away from home.

Security Parameter Index (SPI)

An integer that specifies the row in the SADB (security associations database) that a receiver should use to decrypt a received packet.


The path followed by a datagram while it is encapsulated.

Virtual Private Network

A single, secure, logical network that uses tunnels across a public network such as the Internet.

visited network

A network other than a mobile node's home network, to which the mobile node is currently connected.

visitor list

The list of mobile nodes visiting a foreign agent.