Electrical computers and digital processing systems: multicomput – Computer-to-computer protocol implementing
Reexamination Certificate
1999-06-02
2004-06-15
Harvey, Jack B. (Department: 2144)
Electrical computers and digital processing systems: multicomput
Computer-to-computer protocol implementing
C709S201000, C709S220000, C714S004110, C379S219000, C379S309000
Reexamination Certificate
active
06751672
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention relates in general to a home agent discovery algorithm and system for a computer protocol and in particular to an efficient and improved dynamic home agent discovery algorithm and system for a computer protocol that provides efficient communications and utilization of resources between a mobile computer system or device and other systems and devices, especially when the mobile computer system or device has moved from one location to another location.
2. Description of the Related Art
Computers or computer systems/devices that communicate with each other over the Internet and a home network require the use of a protocol or Internet protocol (IP).
FIG. 1
is a prior art figure of a mobile computer
10
in communications with a home network
12
at one location which is moved to another location that is in communications to the Internet
14
. The configuration in
FIG. 1
requires a base mobile Internet protocol (IP) for providing and routing communications between computer systems and devices, especially when the mobile computer
10
has moved from one location to another location (i.e. moved from being in communication with the home network
12
to being in communication with the Internet
14
). Current protocols require the use of dynamic home agent discovery algorithms in order for the mobile node
11
to discover the IP address of its home agent
16
. However, inefficiencies and problems exist with current protocols, such as the base mobile Internet protocol (IP), that use present dynamic home agent discovery algorithms.
In discussing these protocols that use dynamic home agent discovery algorithms, the following terms are generally defined:
“Mobile Node” is a host or router that changes its point of attachment from one network or sub-network to another network or sub-network. A mobile node may change its location without hanging its IP address, and it may continue to communicate with other Internet nodes at any location using its (constant or fixed) IP address, assuming link-layer connectivity to a point of attachment is available.
“Home Agent” is a router on a mobile node's home network which tunnels datagrams for delivery to the mobile node when it is away from home and maintains current location information for the mobile node. The home agent has three main operations: 1) sending agent advertisement; 2) receiving a home agent discovery request and processing the discovery request; 3) receiving a registration request and processing the registration request.
“Foreign Agent” is a router on a mobile node's visited network, which provides routing services to the mobile node while registered. The foreign agent detunnels and delivers datagrams to the mobile node that were tunneled by the mobile node's home agent. For datagrams sent by a mobile node, the foreign agent may serve as a default router for registered mobile nodes.
“Agent Advertisement” is an advertisement, message constructed by attaching a special Extension to a router advertisement message.
“Care-of Address” is the termination point of a tunnel toward a mobile node, for datagrams forwarded to the mobile node while it is away from home. The protocol is able to use 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 and 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.
“Correspondent Node” is a peer which is communicating with a mobile node. A correspondent node may be either mobile or stationary.
“Home Address” is an IP address, that is assigned for an extended period of time to a mobile node. It remains unchanged regardless of where the node is attached to the Internet.
“Home Network” is a network, possibly virtual, having a network prefix matching that of a mobile node's home address. Standard IP routing mechanisms will deliver datagrams destined to a mobile node's Home Address to the mobile node's Home Network.
“Link” is a facility or medium over which nodes are able to communicate at the link layer. A link underlies the network layer.
“Mobility Agent” is either a home agent or a foreign agent.
“Mobile Node's Failure Recovery Information” is the minimal amount of information required to recover the mobile node's operation if its serving home agent failed. The mobile node's failure recovery information should contain at least a mobile node's care-of address, mobile node's home IP address, registration lifetime, and registration flags.
“All Home Agents Multicast Address” is a D class address (multicast address) which is assigned to the set of home agents on the Internet Service Provider (ISP) network. It is recommended for mobile nodes to use this address to access home agents instead of subnet-directed broadcast address for efficiency reasons.
Computer networks and Internet links have been existence for several years. Also, wireless access and communications to these networks and to the Internet have also been in use. However, current protocols that use present dynamic home agent discovery algorithms and systems to handle and deal with communications of mobile computers to the Internet and network, such as base mobile IP, result in various problems and shortcomings.
These present protocols that use dynamic home agent discovery algorithms and systems inefficiently use wireless access and communication resources and network resources. For example, prior art
FIGS. 2 and 3
show a mobile computer
10
with a mobile node
11
that communicates (through the Internet
14
having a relatively low bandwidth) with a home network
12
having a relatively large or infinite bandwidth.
One inefficiency problem with present protocols that use dynamic home agent discovery algorithms or systems stems from the fact that agent advertisement must be used by the protocol in order to detect motion and location of a mobile node
11
. Prior art
FIG. 2
shows mobility agents, such as home agents
16
or foreign agents, advertising their presence to a mobile node(s)
11
via agent advertisement messages. Each and every home agent
16
advertises its presence to the mobile node
11
as shown in FIG.
2
. In this example, wireless networks have a set of RF channels, which is used for communication between hosts (i.e. home agents
16
) and mobile nodes
11
. When a host (i.e. home agents
16
) wants to send a packet to a mobile node
11
, the mobile node
11
is allocated one of these RF channels. Packet communication between the host (i.e. home agents
16
) and the mobile node
11
commences once one of the RF channels is allocated. Many other mobile nodes
11
would also be-allocated various RF channels. If multiple home agents
16
are periodically sending agent advertisement messages, where the period between transmission, for example, is one (1) second, then low optimization of the RF bandwidth would result causing inefficient use of scarce wireless access and communication resources. A similar inefficiency problem with use of network bandwidth also exists on the network side. Thus, inefficient usage of wireless network resources, such as the use of RF channels, results from the present home dynamic home agent discovery algorithms and systems if multiple home agents send agent advertisement messages.
Another inefficiency problem with current protocols that use dynamic home agent discovery algorithms involves the mobile node
11
having to register and the home agents
16
having to reply to the registration requests. The mobile node
11
registers directly with its home agent
16
. However, the mobile node
11
may not know the IP address of its home agent
16
, and the mobile node
11
then uses the dynamic home agent discovery algorithms to automatically determine the IP address of its home agent
16
. In this case, as shown in prior art
FIG. 3
, the mobile node
11
must send a home agent discovery request to each hom
Akhtar Haseeb
Khalil Mohamed
Qaddoura Emad
Crane John D.
Dillon & Yudell LLP
Harvey Jack B.
Nortel Networks Limited
Tran Lambert
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