Mobile IPMobile IP was designed to allow mobile device users
to move from one network to another .Enables hosts to stay connected to the Internet
regardless of their location.Enables hosts to be tracked without needing to
change their IP address.Requires no changes to software of non-mobile
hosts/routers.Has no geographical limitations.Supports security.
Standardized by IETF .
Mobile IP EntitiesMobile Node (MN)
The entity that may change its point of attachment from network to network in the Internet.
Two addresses:- 1. Home address – IP address assigned to the device
within its home network . 2. Care-of address (COA)– IP address of the device when it
is operating in a foreign network. Identifies Mobile Node’s current location. Sent by Foreign Agent to Home Agent when MN attaches. Usually the IP address of the Foreign Agent.
Mobile IP EntitiesHome Network – The network within which the
device receives its Home address Home Agent (HA)
Stores information about Mobile nodes whose permanent Home address is in Home Agent’s Network.
Located on home network of Mobile Node.Does mobility binding of MN’s IP with its COAForwards packets to network when MN is away
Does this through encapsulation
Mobile IP Entities contd.Foreign network – Network in which the Mobile Node is
away from its Home network.Foreign Agent (FA)
Stores information about mobile nodes visiting its network. If MN is away from HA then it uses a FA to send/receive
data to/from HAAdvertises Care-of addresses which are used by Mobile IP.Decapsulates messages for delivery to MN
Binding – Association of Home address with Care-of address.
Correspondent Node(CN) – End host of MN.
Mobile IP OperationAgent Discovery
HA’s and FA’s broadcast their presence on each network to which they are attached
MN’s listen for advertisement and then initiate registration
Encapsulation – Attaching COA to the packet with HADecapsulation –Detaching COA to the packet with HARegistration
When MN is away, it registers its COA with its HA Registration happens as often as MN changes networks There is a specific lifetime for service for registration There is also a de-registration process if an MN returns
home
Mobile IP OperationA MN listens for agent advertisement and then
initiates registrationAfter receiving the registration request from a MN,
FA request to HAThe HA acknowledges and registration is completeHA intercepts all packets destined for MNHA then encapsulates all packets addressed to MN
and forwards them to FAFA decapsulates all packets addressed to MN and
forwards them via hardware address
Tables maintained on routersMobility Binding Table
Maintained on HA of MN Maps MN’s home address
with its current COA
Visitor List Maintained on FA Maps MN’s home address
HA address
Mobile IP ProblemsSingle HA model may be damaged
Possible solution – have multiple HAFrequent reports to HA if MN is moving
ApplicationsFound in Wired and Wireless environments.Able to carry mobile devices across Multiple
LANS.
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