The Internet is in some ways like the proverbial massive software project whose requirements keep changing, and which is never completed. When the Internet protocols were first designed, there was no concept of the future requirement that IP would need to support mobility. In today’s wireless world, mobility support is one of the key requirements for IP. Like the requirements for QoS, security, and multimedia support, the mobility requirement has arisen due to the phenomenal success of the Internet, as a result of which people want to do more and more things over the Internet.
Key Terms in this Chapter
Forwarding Agent: A network element that forwards packets addressed to a mobile node to the current location of the mobile node. This is a non-standard term introduced by us to represent this concept that is not explicitly defined in the Mobile IPv6 specifications.
Interception Agent: A network element that intercepts packets addressed to a mobile node, so that they are not lost due to the mobile node having moved elsewhere. This is a non-standard term introduced by us to represent this concept that is not explicitly defined in the Mobile IPv6 specifications.
Home Agent: A key element in mobile IP and mobile IPv6, where it serves as a combination of an interception agent and forwarding agent.
Home Address: An IP address that is assigned to a mobile node for a long time, typically in its home network.
Mapping Database: In redirection-based IP mobility protocols, the mapping database is where the location information of the MNs are stored (bindings of permanent IP address and care-of address). The term “mapping database” itself is a non-standard term introduced by us to capture a concept common to different redirection-based mobility protocols. It goes by different names in the different protocols (e.g., location register in MIP-LR).
Correspondent Node (CN): A machine that communicates with a MN; a CN may or may not be mobile.
Care-Of Address (CoA): The current address of a mobile node, at which it can be reached when it is roaming in a foreign network that is different from its home network.
Home Network: The network where a mobile node can be found whenever it is not roaming in another network. It can be thought of as a default network.
Mobile Node (MN): A machine that moves around and connects to the network through different network attachment points.