2. What is Mobile Network?
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The mobile network layer, also known as the network layer or layer 3, is the third
layer in the OSI model and is responsible for providing end-to-end
communication between different networks.
In the context of mobile networks, the network layer is responsible for routing
packets of data between mobile devices and the core network.
Some of the key functions of the mobile network layer include:
Addressing: Assigning unique addresses to mobile devices so that they can
be identified on the network.
Routing: Determining the most efficient path for data packets to travel from
the source device to the destination device.
Fragmentation and reassembly: Breaking up large data packets into smaller
pieces (fragments) and then reassembling them at the destination.
Error control: Detecting and correcting errors in the data transmitted over
the network.
In mobile networks, the network layer is implemented using various protocols,
including IP (Internet Protocol), ICMP (Internet Control Message Protocol),
and ARP (Address Resolution Protocol).
3. Mobile IP
Mobile IP is a protocol used in mobile networks to allow mobile devices to
maintain their IP address as they move between different networks.
Normally, when a device moves from one network to another, it is assigned a
new IP address by the new network.
This can cause problems for applications that are in the middle of a session,
as the IP address change may cause the session to be interrupted or
terminated.
When a device moves to a new network, it sends a message to its home
network, informing it of its new location.
The home network then forwards any incoming messages to the device's
current location, using a technique known as tunneling.
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4. Cont…
Tunneling involves encapsulating the IP packets in a new packet, with a new IP
header that includes the device's current IP address.
The encapsulated packet is then sent to the device's current location, where it is
decapsulated and delivered to the device.
Mobile IP is based on the Internet Protocol (IP) and is compatible with both IPv4
and IPv6.
It is commonly used in wireless networks, such as cellular networks and Wi-Fi
networks, where devices frequently move between different access points or base
stations.
Overall, Mobile IP allows mobile devices to maintain their connectivity as they move
between different networks, without the need for applications to be interrupted or
restarted.
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5. Mobile IP Entities and Terminologies
In Mobile IP, there are several entities and terminologies that are used to facilitate
the movement of a mobile device across different networks while maintaining the
same IP address.
Some of the important entities and terminologies in Mobile IP include:
Mobile Node (MN): A mobile device that can move between different networks
while maintaining the same IP address.
Home Network: The network to which the Mobile Node is originally connected,
and where its home address is registered.
Home Agent (HA): A router on the home network that is responsible for routing
packets to the Mobile Node when it is away from its home network.
Care-of Address (CoA): The IP address assigned to the Mobile Node when it is
away from its home network. The CoA is used to route packets to the Mobile
Node while it is away from its home network.
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6. Cont…
Foreign Network: The network in which the Mobile Node is currently located,
and where it has been assigned a Care-of Address.
Foreign Agent (FA): A router on the foreign network that acts as a proxy for the
Mobile Node, forwarding packets to the Mobile Node's CoA.
Correspondent Node (CN): A device with which the Mobile Node wants to
communicate.
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7. IP Packet Delivery
IP packet delivery refers to the process by which packets of data are
transmitted from one device to another over an IP network.
This process involves several steps:
Packet Creation: The process begins when an application generates data to
be transmitted.
The data is divided into smaller units called packets, and each packet is
assigned a unique packet identifier (IP address) and a sequence number.
Packet Routing: Once the packets are created, they are sent to the network
layer, where the source device determines the best route for the packets to
reach the destination device.
This is done using routing algorithms, which determine the optimal path
through the network based on factors such as network topology, available
bandwidth, and congestion levels.
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8. Cont…
Packet Forwarding: Once the optimal route is determined, the packets are
forwarded through the network, with each router along the way forwarding the
packets to the next router in the chain, until the packets reach their destination.
Packet Delivery: Once the packets reach their destination, they are reassembled
into their original format and delivered to the appropriate application layer
protocol.
o Generally, to ensure that packets are delivered to the correct location, the Mobile
IP protocol uses a combination of encapsulation, tunneling, and routing
techniques to ensure that packets are routed to the correct destination, regardless
of the mobile device's location.
o This involves the use of Home Agents, Foreign Agents, Care-of Addresses, and
other components, which work together to ensure that packets are delivered to the
correct destination.
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