Anycast binding mobile communication method and system

Details Anycast binding mobile communication method and system Anycast binding mobile communication method and system

1999-10-19

2004-04-13

Chin, Vivian (Department: 2682)

Multiplex communications

Communication over free space

Having a plurality of contiguous regions served by...

C370S338000, C370S401000, C455S432100, C455S442000, C455S436000, C455S445000

Reexamination Certificate

active

06721291

ABSTRACT:

FIELD OF THE INVENTION
Mobile communications networks are being used to support the Internet. Mobile Internet terminals (mobile nodes) require support as they move within the wireless network. The present invention efficiently solves the problem of mobile Internet connectivity while preserving bandwidth.
DEFINITIONS
Care-of-Address
Termination point of a tunnel
toward a mobile node, for data packets
forwarded to the mobile node while it
is away from home. There are two
different types of care-of-address: a
foreign agent care-of-address is an
address of a foreign agent with which
the mobile node is registered; a
co-located care-of-address is an
externally obtained local address which
the mobile node has associated with
one of its own network interfaces.
Foreign Agent
A router on a mobile node's visited network
that cooperates with the home agent to complete
the delivery of data packets to the mobile node
while it is away from home.
Home Address
An IP address assigned to a mobile node
Home Agent
A router on a mobile node's home
each.
Host
Any node that is not a router
IP
Internet Protocol
Interface
A node's attachment to a link.
Link
A communication facility or medium over which
nodes can communicate at the link layer, such
as Ethernet (simple bridged). A link is the
layer immediately below IP.
Mobile Node
A node that can change its point of contact to a
network.
Mobility Binding
The association of a home address with care-of-
address, for the remaining lifetime of that
association
Node
A device that implements IP.
Packet
An IP header plus payload.
Tunnel
The path followed by a data packets while it is
encapsulated. While encapsulated a data packet
is routed to a knowledgeable agent, that
decapsulates the data packet and then forwards
it to its ultimate destination.
BACKGROUND OF THE INVENTION
Mobile communications networks, commonly designated as cellular networks, are rapidly expanding to support more services beyond voice service. One of the new services is the running of Internet Protocols (IP) to support mobile access to the Internet. When mobile users access the Internet and are moving geographically the connection must be handed over between connection nodes to maintain the connection to the Internet. Handovers result from a range limitation due to the geographic limitation of communication distances between nodes within a mobile communication network.
Handovers are likely to occur while the terminal is moving within a wireless network with several access points. Simultaneous bindings are used to ensure that handovers are as smooth as possible. Using this type of binding, data packets are simultaneously routed through several access points within the geographical area surrounding the user's last access point called a mobile node.
The problem with this solution is that excess bandwidth is used because the same data packet is sent through many access points to the terminal. The excess data packets are simply discarded at the terminal resulting in wasted transmission capacity. It is more efficient to send data packets only once to a mobile terminal.
Current Solutions to IP Mobility:
One system for providing mobility to the Internet is described in a paper published in IEEE May 1997 issue at pages 84-99, by Charles E. Perkins, of Sun Microsystems. In addition, an Internet document specifies protocol enhancements that allow transparent routing of IP datagrams to mobile nodes in the Internet and can be found at http://sunsite.auc.dk/RFC/rfc/ rfc2002.html (incorporated herein by reference in its entirety). In his May 1997 article, Mr. Perkins describes Agent Advertisement, Registration, and Tunneling as methods to support mobile IP. He further describes route optimization techniques. The following is an excerpt from Mr. Perkins paper describing the protocol, found at page 86.
“Mobile IP is a way of performing three related functions:
Agent Discovery—Mobility Agents advertise their availability on each link for which they provide service.
Registration—When the mobile node is away from home, it registers care-of-address with its home agent.”
Tunneling—In order for datagrams to be delivered to the mobile node when it is away from home, the home agent has to tunnel the datagrams to the care-of-address.
“The following will give a rough outline of operation of the mobile IP protocol, making use of the above-mentioned operations.
FIG. 1
(not shown) may be used to help envision the roles played by the entities.
Mobility agents make themselves known by sending agent advertising messages. An impatient mobile node may optionally solicit an agent advertisement message.
After receiving an agent advertisement, a mobile node determines whether it is on its home or a foreign network. A mobile node basically works like any other node when it is at home.
When a mobile node moves away from its home network, it obtains a care-of-address on the foreign network for instance, by soliciting or listening for agent advertisement, or contacting Dynamic Host Configuration Protocol (DHCP) or Point-to-Point (PPP).
While away from home, the mobile node registers each new care-of-address with its home agent, possibly by way of a foreign agent.
Datagrams sent to the mobile node's home address are intercepted by its home agent, tunneled by its home agent to the care-of-addresses, received at the tunnel endpoint (at either a foreign agent or the mobile node itself), and finally delivered to the mobile node.
In the reverse direction, datagrams sent by the mobile node are generally delivered to their destination using standard IP routing mechanisms, not necessarily passing through the home agent (but see the eighth section).”
“When the home agent tunnels a datagram to the care-of-address, the inner IP header destination (i.e., the mobile node's home address) is effectively shielded from the intervening routers between its home network and its current location. At the care-of-address, the original datagram exits from the tunnel and is delivered to the mobile node.”
“It is the job of every home agent to attract and intercept datagrams that are destined to the home address of any of its registered mobile nodes. The home agent basically does this by using a minor variation on Address Resolution Protocol (ARP), and to do so in the natural mode it has to have a network interface on the link indicated by the mobile node's home address. However, the latter requirement is part of the mobile IP specification. When foreign agents are in use, similarly, the natural mode of operation suggests that the mobile node be able to establish a link to its foreign agent. Other configurations are possible, however, using protocol operations not defined by (and invisible to) mobile IP. Notice that, if the home agent is the only router advertising reachability to the home network, but there is no physical link instantiating the home network, then all datagrams transmitted to mobile nodes addressed on that home network will naturally reach the home agent without any special link operations.”
“
FIG. 1
(not shown) illustrates the routing of datagrams to and from a mobile node away from home, once the mobile node has registered with its home agent. The mobile node is presumed to be using a care-of-address provided by the foreign agent:
A datagram to the mobile node arrives on the home network via standard IP routing.
The datagram is intercepted by the home agent and is tunneled to the care-of-address, as depicted by the arrow going through the tube.
The datagram is de-tunneled and delivered to the mobile node.
For datagrams sent by the mobile node, standard IP routing delivers each to its destination. In the FIG. (
1
) sic, the foreign agent is the mobile node's default router.’
Further background on mobile IP can be found in another paper by Mr. Charles Perkins, Sun Microsystems and David B. Johnson, Carnegie Mellon University prepared for by the Mobile IP Working Group of the Internet Engineering Task Force (IETF), dated Feb. 25, 1999. Online reference: http://search.ietf.org/internet-drafts/. In t

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