In this era of mobile internet, a major component in the network is the Mobile Switching Center (MSC), whose primary service is the routing of calls and data services. It is through this center that end-to-end connection services, handover, and mobility requirements are handled. This center is useful in locating the user receiving data or other services. In this context, the Home Agent refers to the router that is used as a databank for the user whose number is being sought. The Home Agent can retrieve the user’s current position and select what base station to use to form a connection from this data.
The home agent allocates the user an IP address used by the node within its home network. The Foreign Agent refers to the router that can be used to retrieve information about a visiting user. The foreign agent advertises such nodes using a care-of address, which the home agent can use to reach the user. This care of address is a foreign IP address allocated to visiting users and broadcast. The foreign agent may be an alternative router if the user is moving from one point to another.
Triangular routing stems from a routing algorithm that sends a packet of data through a second party, such as the foreign agent, before reaching the recipient. This is likely to result in the problem of triangular routing in a case where the recipient sends a response that will be routed back to the home agent. To solve this problem, packets sent back by the recipient need to be sent directly to the source. This calls for mechanisms such as tunneling, which direct all responses back to the home agent as well for proper routing of the response. The home agent will possess the correct address to which it can route the response.