13-09-2012, 12:09 PM
MOBILE IP - WIRELESS COMMUNICATION
[attachment=33676]
INTRODUCTION
Mobile devices can be connected to the Internet by using wireless network interfaces. However, due to roaming, a mobile device may change its network attachment each time it moves to a new link. It is therefore required that efficient protocols will be able to inform the network about this change in network attachment such that the Internet data packets will be delivered in a seamless way to the new point of attachment. Such a protocol is the mobile IP protocol that has been developed by the Mobile IP Internet.
The Mobile Internet Protocol, or better known as Mobile IP, is a protocol that adds to the already existing Internet Protocol by making the movement of a node transparent to applications on its original network. One knows that a host address is made up of a network number and a host part. This network number tells the user what network the host is attached to. Original Internet Protocol algorithms tell certain routers how to get packets to their correct networks.
Now with the regular Internet Protocol if the host disconnected itself from its original network and joined another network, the host would never receive any packets because the host has the same IP address from its old network that would not be recognized by the network in which it joined.
In essence the host would seem to be missing because its IP address does not match its new network number and therefore would never receive any packets. Because of this problem, Mobile IP was created so that mobile nodes could freely move from network to network without the fear of losing data or interrupting current computer applications and settings.
MOBILE IP
DEFINITION
Mobile IP is a standard communication protocol, defined to allow mobile device users to move from one network to another while maintaining their permanent IP address.
The Mobile IP protocol allows the MNs to retain their IP address regardless of their point of attachment to the network. This can be fulfilled by allowing the MN to use two IP addresses. The first one, called home address, is static and is mainly used to identify higher layer connections, e.g., TCP. The second IP address that can be used by a MN is the Care-of Address. While the mobile is roaming among different networks, the Care-of Address changes. The reason of this is that the Care-of Address has to identify the mobile’s new point of attachment with respect to the network topology. In Mobile IPv4 the Care-of Address management is achieved by an entity called Foreign Agent.
The Mobile Node, using its home address is appearing to be able to receive data on its home network, through a Home Agent. In the situation that the mobile roams into a foreign network, it will need to obtain, a new Care-of Address via the Foreign Agent. Note that, in this situation the Mobile Node can also obtain a new Care-of Address by contacting the Dynamic Host Configuration Protocol (DHCP) [RFC1541] or Point-to-Point Protocol (PPP) [RFC1661]. This new Care-of Address will be registered with its Home Agent. The Home Agent receives a packet that has to be sent to the mobile, it delivers it from the home network to the mobile’s Care-of Address.
WHY MOBILE IP IS USED?
Mobile IP is most useful in environments where mobility is desired and the traditional land line dial-in model or DHCP do not provide adequate solutions for the needs of the users. If it is necessary or desirable for a user to maintain a single address while they transition between networks and network media, Mobile IP can provide them with this ability.
Generally, Mobile IP is most useful in environments where a wireless technology is being utilized. This includes cellular environments as well as wireless LAN situations that may require roaming. Mobile IP can go hand in hand with many different cellular technologies like CDMA, TDMA, GSM, AMPS, NAMPS, as well as other proprietary solutions, to provide a mobile system which will scale for many users.
Mobility is changing people’s perspective on the Internet. With the increasing number and variety of mobile devices, such as PDAs, laptops, and cellular phones, more and more Internet services will be accessible by moving users, through the widely deployed wireless networks. Mobility management is the fundamental technology to automatically support the seamless access to mobile services.
Future mobile communication systems are evolving with the trend of global connectivity through the internetworking and interoperability of heterogeneous wireless networks. Roaming within such networks will be more complex.
AGENT DISCOVERY
A Mobile Node discovers its Foreign and Home Agents during agent discovery.During the agent discovery phase, the Home Agent and Foreign Agent advertise theirServices on the network by using the ICMP Router Discovery Protocol (IRDP). TheMobile Node listens to these advertisements to determine if it is connected to its homeNetwork or foreign network.
The IRDP advertisements carry Mobile IP extensions that specify whether agent is aHome Agent, Foreign Agent, or both; its care-of address; the types of services it willprovide such as reverse tunneling and generic routing encapsulation (GRE); and the allowed registration lifetime or roaming period for visiting Mobile Nodes. Rather thanwaiting for agent advertisements, a Mobile Node can send out an agent solicitation. Thissolicitationforces any agents on the link to immediately send an agent advertisement.If a Mobile Node determines that it is connected to a foreign network, it acquires a care of Address.
REGISTRATION
The Mobile Node registers its current location with the Foreign Agent and Home Agent during registration.The Mobile Node is configured with the IP address and mobility security association(which includes the shared key) of its Home Agent.
In addition, the Mobile Node isconfigured with either its home IP address, or another user identifier, such as a Network AccessIdentifier. The Mobile Node uses this information along with the information that it learns from theForeign Agent advertisements to form a Mobile IP registration request.
CONCLUSION
The number of wireless devices for voice or data is projected to surpass the number of fixed devices. Mobile data communication will likely emerge as the technology supporting most communication including voice and video. Mobile data communication will be pervasive in cellular systems such as 3G and in wireless LAN such as 802.11, and will extend into satellite communication. Network mobility is enabled by Mobile IP, which provides a scalable, transparent, and secure solution. Mobile IP enables advanced applications such as unified messaging. Though mobility may be enabled by link-layer technologies, data crossing networks or different link layers is still a problem. The solution to this problem is a standards-based protocol, Mobile IP.
[attachment=33676]
INTRODUCTION
Mobile devices can be connected to the Internet by using wireless network interfaces. However, due to roaming, a mobile device may change its network attachment each time it moves to a new link. It is therefore required that efficient protocols will be able to inform the network about this change in network attachment such that the Internet data packets will be delivered in a seamless way to the new point of attachment. Such a protocol is the mobile IP protocol that has been developed by the Mobile IP Internet.
The Mobile Internet Protocol, or better known as Mobile IP, is a protocol that adds to the already existing Internet Protocol by making the movement of a node transparent to applications on its original network. One knows that a host address is made up of a network number and a host part. This network number tells the user what network the host is attached to. Original Internet Protocol algorithms tell certain routers how to get packets to their correct networks.
Now with the regular Internet Protocol if the host disconnected itself from its original network and joined another network, the host would never receive any packets because the host has the same IP address from its old network that would not be recognized by the network in which it joined.
In essence the host would seem to be missing because its IP address does not match its new network number and therefore would never receive any packets. Because of this problem, Mobile IP was created so that mobile nodes could freely move from network to network without the fear of losing data or interrupting current computer applications and settings.
MOBILE IP
DEFINITION
Mobile IP is a standard communication protocol, defined to allow mobile device users to move from one network to another while maintaining their permanent IP address.
The Mobile IP protocol allows the MNs to retain their IP address regardless of their point of attachment to the network. This can be fulfilled by allowing the MN to use two IP addresses. The first one, called home address, is static and is mainly used to identify higher layer connections, e.g., TCP. The second IP address that can be used by a MN is the Care-of Address. While the mobile is roaming among different networks, the Care-of Address changes. The reason of this is that the Care-of Address has to identify the mobile’s new point of attachment with respect to the network topology. In Mobile IPv4 the Care-of Address management is achieved by an entity called Foreign Agent.
The Mobile Node, using its home address is appearing to be able to receive data on its home network, through a Home Agent. In the situation that the mobile roams into a foreign network, it will need to obtain, a new Care-of Address via the Foreign Agent. Note that, in this situation the Mobile Node can also obtain a new Care-of Address by contacting the Dynamic Host Configuration Protocol (DHCP) [RFC1541] or Point-to-Point Protocol (PPP) [RFC1661]. This new Care-of Address will be registered with its Home Agent. The Home Agent receives a packet that has to be sent to the mobile, it delivers it from the home network to the mobile’s Care-of Address.
WHY MOBILE IP IS USED?
Mobile IP is most useful in environments where mobility is desired and the traditional land line dial-in model or DHCP do not provide adequate solutions for the needs of the users. If it is necessary or desirable for a user to maintain a single address while they transition between networks and network media, Mobile IP can provide them with this ability.
Generally, Mobile IP is most useful in environments where a wireless technology is being utilized. This includes cellular environments as well as wireless LAN situations that may require roaming. Mobile IP can go hand in hand with many different cellular technologies like CDMA, TDMA, GSM, AMPS, NAMPS, as well as other proprietary solutions, to provide a mobile system which will scale for many users.
Mobility is changing people’s perspective on the Internet. With the increasing number and variety of mobile devices, such as PDAs, laptops, and cellular phones, more and more Internet services will be accessible by moving users, through the widely deployed wireless networks. Mobility management is the fundamental technology to automatically support the seamless access to mobile services.
Future mobile communication systems are evolving with the trend of global connectivity through the internetworking and interoperability of heterogeneous wireless networks. Roaming within such networks will be more complex.
AGENT DISCOVERY
A Mobile Node discovers its Foreign and Home Agents during agent discovery.During the agent discovery phase, the Home Agent and Foreign Agent advertise theirServices on the network by using the ICMP Router Discovery Protocol (IRDP). TheMobile Node listens to these advertisements to determine if it is connected to its homeNetwork or foreign network.
The IRDP advertisements carry Mobile IP extensions that specify whether agent is aHome Agent, Foreign Agent, or both; its care-of address; the types of services it willprovide such as reverse tunneling and generic routing encapsulation (GRE); and the allowed registration lifetime or roaming period for visiting Mobile Nodes. Rather thanwaiting for agent advertisements, a Mobile Node can send out an agent solicitation. Thissolicitationforces any agents on the link to immediately send an agent advertisement.If a Mobile Node determines that it is connected to a foreign network, it acquires a care of Address.
REGISTRATION
The Mobile Node registers its current location with the Foreign Agent and Home Agent during registration.The Mobile Node is configured with the IP address and mobility security association(which includes the shared key) of its Home Agent.
In addition, the Mobile Node isconfigured with either its home IP address, or another user identifier, such as a Network AccessIdentifier. The Mobile Node uses this information along with the information that it learns from theForeign Agent advertisements to form a Mobile IP registration request.
CONCLUSION
The number of wireless devices for voice or data is projected to surpass the number of fixed devices. Mobile data communication will likely emerge as the technology supporting most communication including voice and video. Mobile data communication will be pervasive in cellular systems such as 3G and in wireless LAN such as 802.11, and will extend into satellite communication. Network mobility is enabled by Mobile IP, which provides a scalable, transparent, and secure solution. Mobile IP enables advanced applications such as unified messaging. Though mobility may be enabled by link-layer technologies, data crossing networks or different link layers is still a problem. The solution to this problem is a standards-based protocol, Mobile IP.