Lectured By: Vivek Dimri Asst Professor CSE Deptt. Sharda University, Gr. Noida

Mobile IP Mobile IP (or MobileIP) is an Internet Engineering Task Force (IETF) standard communications protocol that is designed to allow mobile device users to move from one network to another while maintaining a permanent IP address. Mobile IP specifies enhancements that allow transparent routing of IP datagram to mobile nodes in the Internet. Each mobile node is always identified by its home address, regardless of its current point of attachment to the Internet.

Mobile IP While situated away from its home, a mobile node is also associated with a care-of address, which provides information about its current point of attachment to the Internet. Mobile IP specifies how a mobile node registers with its home agent and how the home agent routes datagram to the mobile node through a tunnel. Mobile IP provides an efficient, scalable mechanism for roaming within the Internet.

Mobile IP Using Mobile IP, nodes may change their point-of- attachment to the Internet without changing their IP address. This allows them to maintain transport and higher- layer connections while moving. The home agent sends datagram destined for the mobile node through a tunnel to the care-of address. After arriving at the end of the tunnel, each datagram is then delivered to the mobile node.

Mobile IP: Example

Mobile IP Terminology Mobile Node (MN) Correspondent Node (CN) Home Network (HN) Foreign Network(FN) Home Agent(HA) Foreign Agent(FA) Care of Address (CoA)

How Mobile IP Works

Agent Discovery One initial problem of an MN after moving is how to find a FA. How does MN discovers that it has moved for this purpose mobile IP describes two methods: Agent Advertisement: For this first method, FA and HA advertise their presence periodically using special agent advertisement messages. These advertisement messages can be seen as a beacon broadcast into the subject. Agent Solicitation: If no agent advertisement are present or the interval time is too high, and MN has not received a CoA by other means e.g. DHCP, the mobile node must send solicitation. If a mobile node does not wish to wait for the periodic advertisement, it can send out Agent Solicitation messages that will be responded by a mobility agent.

Registration Having received a CoA, the MN has to register with the HA. The main purpose of the registration is to inform the HA of the current location for correct forwarding of packets. Registration can be done in two different ways depending upon the location of the CoA.

Registration

Registration Process-1 If the CoA is at the FA, registration is done as shown in figure. The MN sends its registration request containing the CoA to the FA which is forwarding the request to the HA. The HA now sets up a mobility binding containing the mobile node’s home IP address and the current CoA. Registration Process-2 If the CoA is co-located, registration can be simpler. The MN may send the request directly to the HA and vica versa. This is also the registration procedure for MN’s returning to their home network. Here they also registered directly with the HA.

Registration Request

Registration Reply