U.S. patent application number 10/026060 was filed with the patent office on 2002-05-09 for method and system for a low-overhead mobility management protocol in the internet protocol layer.
This patent application is currently assigned to InterDigital Technology Corporation. Invention is credited to Shahrier, Sharif M..
Application Number | 20020055971 10/026060 |
Document ID | / |
Family ID | 39880327 |
Filed Date | 2002-05-09 |
United States Patent
Application |
20020055971 |
Kind Code |
A1 |
Shahrier, Sharif M. |
May 9, 2002 |
Method and system for a low-overhead mobility management protocol
in the internet protocol layer
Abstract
A system and method for supporting mobile Internet communication
is provided which employs a Mobile-Home Database (MHD) for Network
Address Translation routers (NATs). A plurality of Mobile Nodes
(MNs), each having a home network, communicate within the system
via a plurality of Hosts. Each Host is associated with a NAT such
that each NAT is associated with one network, but one or more
Hosts. Each network's NAT's MHD identifies each network's home MNs,
with a) a local address of a current association of the MN with a
Host within the network or b) a binding defined by a local address
of an association of the MN with a Host in a foreign network and
the global address of the NAT of the foreign network. Each
network's NAT's MHD also identifies each visiting MN with a local
address of a current Host association of the MN.
Inventors: |
Shahrier, Sharif M.; (King
of Prussia, PA) |
Correspondence
Address: |
VOLPE AND KOENIG, PC
DEPT ICC
SUITE 400, ONE PENN CENTER
1617 JOHN F. KENNEDY BOULEVARD
PHILADELPHIA
PA
19103
US
|
Assignee: |
InterDigital Technology
Corporation
300 Delaware Avenue Suite 527
Wilmington
DE
19801
|
Family ID: |
39880327 |
Appl. No.: |
10/026060 |
Filed: |
December 19, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10026060 |
Dec 19, 2001 |
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09997992 |
Nov 30, 2001 |
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60270190 |
Feb 21, 2001 |
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60270767 |
Feb 22, 2001 |
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60293847 |
May 25, 2001 |
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60296168 |
Jun 6, 2001 |
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60309046 |
Jul 31, 2001 |
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Current U.S.
Class: |
709/203 ;
709/219 |
Current CPC
Class: |
H04L 61/255 20130101;
H04L 9/40 20220501; H04L 61/2535 20130101; H04W 84/105 20130101;
C07C 69/63 20130101; H04W 40/36 20130101; H04W 36/00835 20180801;
H04W 80/04 20130101; H04W 8/26 20130101; H04L 61/25 20130101; H04W
8/082 20130101; C07D 307/79 20130101; H04L 61/00 20130101; H04W
88/005 20130101; H04L 45/26 20130101; H04L 61/2514 20130101; H04W
8/04 20130101; C07C 43/313 20130101 |
Class at
Publication: |
709/203 ;
709/219 |
International
Class: |
G06F 015/16 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 1, 1999 |
JP |
311703/1999 |
Claims
What is claimed is:
1. A network system for supporting mobile Internet communication
comprising: a plurality of networks, each having: a Network Address
Translation router (NAT) with a unique global address; at least one
Host associated with the network's NAT; and at least one Mobile
Node (MN); each Host having a service area in which it can
communicate data to the MNs; each MN having a home Host in a home
network which defines a default local address which is paired with
the global address of the home network's NAT to define a default
binding of the MN; the NAT of each network having an associated
Mobile-Home Database (MHD) which identifies: each MN, which has the
network as its home network, with: a local address of a current
association of the MN with a Host in the network, or a binding
defined by a local address of an association of the MN with a Host
in a different network and the global address of the different
network's NAT; and each visiting MN, which is a MN currently
associated with a Host within the network, but has a different home
network, with a local address of the current Host association of
the MN; each MN being movable from a location where the MN
communicates data via a first associated Host in a first network
having a first NAT to: a location within the service area of a
second Host within the first network to communicate data via the
second Host by communicating to the MHB of the first NAT a local
address reflecting the MN's association with the second Host; or a
location within the access range of a third Host within a different
second network having a second NAT to communicate data via the
third Host by communicating to the MHB of the second NAT a local
address reflecting the MN's association with the third Host and,
where the second network is not the MN's home network, by also
communicating to the MHB of the MN's home network's NAT a binding
including a new local address reflecting the MN's association with
the third Host and the global address of the second NAT; such that
a data communication from a corresponding node (CN) to a selected
MN is communicated to the selected MN by: establishing a binding
based on the MN's default binding or the binding reflected in the
MHB of the MN's home network's NAT, and directing the communication
to the local address identified for the MN in the MHB of the NAT
with which the binding is established.
2. A network system according to claim 1 wherein at least one
network has a plurality of Hosts and at least one Host is the home
Host for a plurality of MNs.
3. A network system according to claim 1 wherein each network's
NAT's MHD identifies local and global addresses and a location
field such that: each MN, which has the network as its home
network, is identified with: a local address of a current
association of the MN with a Host in the network, a null global
address, and a home flag in the location field, or a binding
defined by a local address of an association of the MN with a Host
in a different network and a global address of the different
network's NAT and an away flag in the location field; and each
visiting MN is identified with: a local address of the current Host
association of the MN, a null global address, and a home flag in
the location field.
4. A method for mobile Internet communication system which includes
a plurality of networks each having a Network Address Translation
router (NAT) and a unique global address, at least one Host
associated with the NAT, and at least one Mobile Node (MN), each
Host having a service area in which it can communicate data to the
MNs, each MN having a home Host and a home network which defines a
default local address which is paired with the global address of
the HN's NAT to define a default binding of the MN, the method
comprising: providing an associated Mobile-Home Database (MHD) for
the NAT of each network which identifies: each MN, which has the
network as its home network, with: a local address of a current
association of the MN with a Host within the network, or a binding
defined by a local address of an association of the MN with a Host
within a different network and the global address of the different
network's NAT; and each visiting MN, which is a MN currently
associated with a Host within the network, but has a different home
network, with a local address of the current Host association of
the MN; when a MN moves from a location where the MN communicates
data via a first associated Host within a first network having a
first NAT to a location within the service area of a second Host
within the first network to communicate data via the second Host,
communicating to the MHB of the first NAT a local address
reflecting the MN's association with the second Host; when a MN
moves from a location where the MN communicates data via the first
associated Host within the first network to a location within the
access range of a third Host within a different second network
having a second NAT, to communicate data via the third Host,
communicating to the MHB of the second NAT a local address
reflecting the MN's association with the third Host and, where the
second network is not the MN's home network, by also communicating
to the MHB of the MN's home network's NAT a binding including a new
local address reflecting the MN's association with the third Host
and the global address of the second NAT; and communicating a data
communication from a corresponding node (CN) to a selected MN by:
establishing a binding with a NAT based on the MN's default binding
or the binding reflected in the MHB of the MN's home network's NAT,
and directing the communication to the local address identified in
the MHB of the NAT with which the binding is established for the
MN.
5. A method according to claim 4 wherein: each network's NAT's MHD
identifies local and global addresses and a location field such
that: each MN, which has the network as its home network, is
identified with: a 24 bit local address of a current association of
the MN with a Host in the network, a null global address, and a
home flag in the location field, or a binding defined by a local
address of an association of the MN with a Host within a different
network and a global address of the different network's NAT and an
away flag in the location field; and each visiting MN is identified
with: a local address of the current Host association of the MN, a
null global address, and a home flag in the location field; and a
binding is established between the CN and an MN based on the
binding reflected in the MHB of the MN's home network's NAT when
the corresponding location field has an away flag.
6. A Network Address Translation router (NAT) for a network system
which includes a plurality of networks, each having a NAT with a
unique global address, at least one Host associated with the NAT
and at least one Mobile Node (MN), each Host having a service area
in which it can communicate data to the MNs, each MN having a home
Host and home network which defines a default local address which
is paired with the global address of the home network's NAT to
define a default binding of the MN, the NAT comprising: a
Mobile-Home Database (MHD) which identifies: each MN, which has as
its home Host, a Host associated with the NAT, with: a local
address of a current association of the MN with a Host associated
with the NAT, or a binding defined by a local address of an
association of the MN with a Host not associated with the NAT and
the global address of the NAT associated with that Host; and each
MN, which is currently associated with a Host associated with the
NAT, but has a home Host which is not associated with the NAT, with
a local address of the current Host association; such that a data
communication from a corresponding node (CN) to a selected MN which
has as its home Host, a Host associated with the NAT, is
communicated to the selected MN by: establishing a binding based on
the MN's default binding or the binding reflected in the MHB of the
NAT, and if the binding is established is established with the NAT,
directing the communication to the local address identified in the
MHB.
7. A NAT according to claim 6 wherein the MHD identifies 24 bit
local and global addresses and a location field such that: each MN,
which has as its home Host, a Host associated with the NAT, is
identified with: a 24 bit local address of a current association of
the MN with a Host associated with the NAT, a null global address,
and a home flag in the location field, or a binding defined by a 24
bit local address of an association of the MN with a Host not
associated with the NAT and a 24 bit global address of the NAT
associated with that Host and an away flag in the location field;
and each MN, which is currently associated with a Host associated
with the NAT, but has a home Host which is not associated with the
NAT, is identified with: a 24 bit local address of the current Host
association of the MN, a null global address, and a home flag in
the location field.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority from U.S. Provisional
Patent Application Ser. No. 60/270,190, filed Feb. 21, 2001; U.S.
Provisional Patent Application Ser. No. 60/270,767, filed Feb. 22,
2001; U.S. Provisional Patent Application Ser. No. 60/296,168,
filed Jun. 6, 2001; U.S. Provisional Patent Application Ser. No.
60/293,847, filed May 25,2001; U.S. Provisional Patent Application
Ser. No. 60/309,046, filed Jul. 31, 2001 and U.S. patent
application Ser. No. 09/997,992, filed Nov. 30, 2001.
FIELD OF THE INVENTION
[0002] The present invention relates to a system and method of
mobile Internet communication. Specifically the present invention
relates to managing the mobility of Mobile Nodes (MNs) within
multiple administrative domains employing Network Address
Translation enabled routers (NATs) for Internet communications.
BACKGROUND OF THE INVENTION
[0003] Network Address Translation enabled routers (NATs) are used
for connecting private networks to the Internet. As illustrated in
FIG. 2, conventional Internet communications are conducted by
establishing 48 bit bindings between NATs which identify nodes
which are communicating with each other. The address space is
divided into a set of registered 24 bit global addresses and a set
of unregistered 24 bit local addresses by the Internet Address
Numbers Authority (IANA). Private networks can use any address from
the unregistered address space. The public or global addresses are
registered and one address from this pool is assigned to each
NAT.
[0004] The inventor has recognized that it would be desirable to
modify the traditional Network Address Translation functions to
handle the cases where Mobile Nodes (MNs) are allowed to migrate
within their own private networks and where MNs are allowed to
migrate from one private network to another.
SUMMARY
[0005] A system and method for supporting mobile Internet
communication is provided which has a plurality of networks. Each
network has a Network Address Translation router (NAT) with a
unique global address, at least one Host associated with the NAT
and at least one Mobile Node (MN). The Mobile Nodes (MNs)
communicate within the system via the Hosts.
[0006] Each Host is associated with one NAT and has a service area
in which it can communicate data to the MNs. Each MN has a home
Host within a home network which defines a default local address
which is paired with the global address of the home network's NAT
to define a default binding of the MN.
[0007] The invention provides the NAT of each network with an
associated Mobile-Home Database (MHD) which identifies each MN,
which has the network as its home network, with a) a local address
of a current association of the MN with a Host within the network
or b) a binding defined by a local address of an association of the
MN with a Host within a different network and the global address of
the different network's NAT. Each network's NAT's MHD also
identifies each visiting MN, i.e. an MN which is currently
associated with a Host associated with the NAT, but has a different
home network, with a local address of the current Host association
of the MN.
[0008] Each MN can be moved from a location where the MN
communicates data via a first associated Host within a first
network having a first NAT to a location within the service area of
a second Host within the first network to communicate data via the
second Host. MN communication via the second host is enabled by
communicating to the MHB of the first NAT a local address
reflecting the MN's association with the second Host.
[0009] Each MN can also be moved from a location where the MN
communicates data via the first associated Host within the first
network to a location within the access range of a third Host
within a different second network having a second NAT to
communicate data via the third Host. MN communication via the third
Host is enabled by communicating to the MHB of the second NAT a
local address reflecting the MN's association with the third Host.
Where the second network is not the MN's home network, the MN also
communicates to the MHB of the MN's home network's NAT a binding
including a new local address reflecting the MN's association with
the third Host and the global address of the second NAT.
[0010] The system enables a data communication from a corresponding
node (CN) to a selected MN to be communicated to the selected MN by
establishing a binding based on the MN's default binding or the
binding reflected in the MHB of the MN's home network's NAT. The
NAT with which the binding is established directs the communication
to the local address identified in its MHB for the MN.
[0011] A preferred the system includes at least one network
associated with a plurality of Hosts and at least one Host which is
the home Host for a plurality of MNs. Nodes that are not mobile may
also be associated with the Hosts within the system. These nodes
can be identified in the Host's network's MHD or the network's NAT
can be configured to bypass the MHD for communications directed to
non-mobile nodes.
[0012] Preferably, the NAT's MHD of each network identifies 24 bit
local and global addresses and a location field. Each MN, which has
the network as its home network, is identified in the NAT's MHD
with a) a local address of a current association of the MN with a
Host within the network, a null global address, and a home flag in
the location field or b) a binding defined by a local address of an
association of the MN with a Host in a different network and a
global address of the different network's NAT and an away flag in
the location field. Each visiting MN is preferably identified in
the visited network's NAT's MHD with a local address of the current
Host association of the MN, a null global address, and a home flag
in the location field. A binding is established between a
source/corresponding node (CN) and an MN based on the binding
reflected in the MHD of the MN's home network's NAT when the
corresponding location field has an away flag.
[0013] The present invention can be used to implement an Internet
architecture consisting of a large number private networks,
individually connected to the Internet backbone via NATs. Hosts
within the same private network can communicate with one another,
and also with external Hosts via the Internet backbone. The routers
in each private network maintain their own local routes and routers
in the backbone maintain their own external routes. More
specifically, the routers within a particular domain are not
cognizant of routes outside that domain. Likewise, the backbone
(public) routers are not cognizant of the routes to any local
addresses.
[0014] Other objects and advantages of the system and method will
become apparent to those skilled in the art from the following
detailed description of the invention.
BRIEF DESCRIPTION OF THE DRAWING(S)
[0015] FIG. 1 is a schematic diagram of an architecture and
topology of a mobile network associated with the Internet.
[0016] FIG. 2 is a diagram of a conventional Internet communication
binding.
[0017] FIG. 3 illustrates a portion of a Mobile-Home Database (MHD)
of one of the Network Address Translation Routers (NATs)
illustrated in FIG. 1 in accordance with the teachings of the
present invention.
[0018] FIG. 4 illustrates a portion of a Mobile-Home Database (MHD)
of one of the Network Address Translation Routers (NATs)
illustrated in FIG. 1 in accordance with the teachings of the
present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
[0019] As illustrated in FIG. 1, private networks 10, 12, 20 are
connected to an external Internet backbone via Network Address
Translation enabled routers (NATs). Using such a scheme, large
number of private networks can be connected to the external
Internet backbone. Hosts within different private networks can
communicate with each other via the backbone, using the NAT
registered addresses assigned by IANA. Hosts within the same
private network can communicate with each other using one of the
unregistered addresses. Thus, the registered addresses are globally
unique, while unregistered addresses have local significance only.
The local addresses and the global addresses are mutually exclusive
and are conventionally 24 bits each.
[0020] For example, networks 10, 12 and 20 are connected to the
Internet via NAT enabled routers NAT-A, NAT-B and NAT-N,
respectively. NAT-A, NAT-B and NAT-N are each assigned a unique
Global Address by IANA. Nodes within each private network 10, 12,
20 are assigned local address based upon the Host to which the node
is connected. For example, node MN.sub.0,A0 is illustrated as
connected to the private network 10 via Host.sub.A0, so the local
address of node MN.sub.0,A0 at Host.sub.A0 is a 24 bit code which
indicates this connection. For convenience, in FIGS. 3 and 4, the
global address of a NAT is identified by the NAT name and the local
address indicating a connection between a particular node MN.sub.X
and a Host.sub.X is represented as MN.sub.X@Host.sub.X.
[0021] If a communication and/or data packet is to be sent from a
node in one network to a node in another network, before data
transfer can take place, a conventional NAT table is set up. By
convention the node initiating contact is referred to as a
corresponding node (CN). For node to node communication, the first
set of actions is to establish a binding by the NATs for the
networks to which the nodes are currently connected. The
conventional process is described by the Internet Engineering Task
Forces (IETF) Request for Comments (RFCs) 1631 and 3032. When a
binding is established, an Internet Protocol (IP) data packet can
be sent by the corresponding node (CN) which traverses the global
Internet and reaches NAT of the receiving node based on the binding
established
[0022] FIG. 2 illustrates the format the conventional binding table
established between the CN and the receiving node. The bindings are
made up of the nodes' global and local address combinations. For
example, node MN.sub.0,A0 in network 10 as CN may communicate node
MN.sub.0,B0 in network 20. For node MN.sub.0,A0 the binding data is
the combined Global Address NAT-A and the local address
MN.sub.0,A0@Host.sub.A0. For node MN.sub.0,B0, the binding data is
the combined Global Address NAT-B and local address
MN.sub.0,B0@Host.sub.B0.
[0023] The procedure for sending out a data packet from node
MN.sub.0,A0 to node MN.sub.0,B0 is as follows. The packet is
encoded with the global address NAT-A as the source address and the
global address NAT-B as the destination address is sent from the
source node MN.sub.0,A0. The receiving NAT, NAT-B in this example,
checks the binding in its table, and retrieves the local address of
the receiving node's Host, Host.sub.0B in this example. The packet
is then forwarded to that Host through which it is received by the
node MN.sub.0,B0. Where a node is not mobile, its binding data
represents a permanent address to which any CN may send data under
the conventional binding system and protocols. However, mobile
nodes MN may change location so that simply addressing data to a
prior known address does not assure delivery without some system to
accommodate connection changes by the MN.
[0024] FIGS. 3 and 4 illustrate the architecture used to implement
a micro-mobility protocol between the private networks shown. The
architecture includes an entity called a Mobile-Home Database (MHD)
associated with each NAT. This is a large directory, tightly
coupled to each NAT, for keeping track of the MNs within the
private network. It also indicates when the MN has moved to a
foreign network (FN).
[0025] The MHD for each NAT preferably includes an index field for
each mobile node, a home/away flag field indicating whether a
mobile node is associated with the NAT, a local address or care of
address (COA) field and a NAT address field. Each MN has a home
Host in a home network which defines a Home Address (HA) which is
analogous to the permanent local address of a non-mobile node in
that it is the address that a CN will use to contact the MN. The
default binding for an MN is a combination of the global address of
the MN's home network's NAT and the MN's home address. If at home,
the MN's default binding will be used to establish a NAT/NAT
connection for the CN/MN communication.
[0026] All of the MNs whose home Host is associated with a
particular NAT, i.e. the home network's NAT, have data records in
that NAT's MHD. One convenient way to identify the mobile nodes is
using their default or home address (HA), so the index field of a
network's NAT's MHD preferably lists the HAs of all of the MNs
whose home network is that network to identify the data record for
each MN.
[0027] The flag field represents a logical field, preferably having
a value 0 or a value 1 to represent a home or an away status with
respect to the network. In the present example, 0 is used to
indicate that the MN has a connection with a Host in the network
and 1 is used to indicate that the MN has a connection with a
different network. The local address field (COA) is used to
indicate to which Host the MN is currently connected. Where the
local address field entry is a Host associated with a foreign
network, the global address field contains the global address of
that foreign network's NAT. In such case the flag field is set to
1. When the flag field is 0, the global address value is not needed
since the relevant global address is that of the MHB's NAT.
[0028] FIGS. 3 and 4 illustrate various example records for the
MHDs of NAT-B and NAT-N of the networks 12 and 20, respectively, at
a given point in time as illustrated in FIG. 1.
[0029] Where a MN is in communication with its home Host, as
illustrated with respect to mobile nodes MN.sub.0,B0, MN.sub.B1 and
MN.sub.0,NK, the associated flag field is set to 0 and the local or
COA field entry is the same as the home address. No NAT address
information is required.
[0030] For MNs which are associated with a Host which is not the
MN's home Host, but is a Host in the MN's home network, the MHD of
the MN's home network's NAT has data entries for the flag field as
0 and the local address (COA) as the current association of the MN
with its non-home Host. For example, mobile node MN.sub.1,B0 has a
home host Host.sub.B0, but is illustrated in FIG. 1 as connected to
host Host.sub.B1. The MN is identified in the index field by its
HA, MN.sub.1,B0@HoSt.sub.B0, has 0 in the flag field and has
MN.sub.1,B0@Host.sub.B1 as the COA as set forth in FIG. 3. The NAT
address field information is not needed since the global address
remains the same because Host.sub.B1 and Host.sub.B0 are associated
with the same network with the associated global address, namely
NAT-B.
[0031] Where a MN from one network connects with a host of a
different network, the MN is registered in that network's NAT with
a visiting address. For example, node MN.sub.i,Nk has as its home
host Host.sub.Nk in network 20 which communicates with the Internet
via NAT-N. In FIG. 1, node MN.sub.i,Nk is illustrated as visiting
network 12 in connection with Host.sub.B1 which is associated with
NAT-B. Accordingly, mobile node MN.sub.i,Nk is assigned a visiting
address VA represented as MN.sub.i,Nk@Host.sub.B1 in the MHD of
NAT-B with a flag field 0 indicating its communication with the
Internet through NAT-B and a local address of
[0032] When the mobile node, such as MN.sub.i,Nk, first initiates
communication with the foreign network, for example, network 12, a
communication is sent to the NAT of its home network, in this case,
NAT-N, to enable efficient redirection of communications. The
communication to the MNs home network's NAT changes the NAT's MHD
data with respect to the listing for the MN by setting the flag
field to 1 and providing binding data for further Internet
communications. The binding data is comprised of the assigned
visiting address VA and the global address of the NAT of the
network which the MN is visiting.
[0033] For the example of mobile node MN.sub.i,Nk the MHD of NAT-N
in FIG. 4 reflects a flag value of 1, a local address of
MN.sub.i,Nk@Host.sub.B1 and a NAT address of NAT-B. A corresponding
node attempting to communicate with mobile Node MN.sub.i,Nk will
not be able to establish a binding with NAT-N since the flag in
NAT-N's MHD is set to 1. In that case, the binding is established
with the binding represented by the local address and NAT address
fields for MN.sub.i,Nk's entry in NAT-N's MHD. Communication is
then conducted establishing a binding with the foreign NAT, in the
example NAT-B.
[0034] So long as the visiting MN does not establish an association
with a Host of a different network, it will preferably retain its
visiting address VA identification in the MHD of the NAT whose
network is visiting, which VA will be also reflected in the MHD of
the mobile node's home network's NAT.
[0035] If the visiting mobile node establishes an association with
another Host within the same network that it is visiting, it will
retain its same VA identification in the MHD of the NAT which is
visiting, but will be provided with a new local address. That new
local address will be stored in the visiting MN's MHD record's COA
field and the visited network's NAT will direct communications to
the MN based on that COA data. No change is required in the MN's
home network's NAT's MHD in such case. For example, if MN.sub.i,Nk
switches its association with Host.sub.B1 and connects to
Host.sub.B0, the COA entry in the MHD of NAT-B will be changed from
MN.sub.i,Nk@Host.sub.B1 to MN.sub.i,Nk@Host.sub.B0 and no change
will be made in the entries in the MHD of NAT-N.
[0036] Preferably, the hosts will periodically determine whether a
connection is still established with a visiting MN. If the visited
host determines that the MN has disconnected and the MN has not
established a connection with another host, the visited host can
communicate this fact to its associated NAT which will change the
COA for the visiting MN's entry to a null data state. An example of
this is the entry for visiting node MN.sub.h,Pq in FIG. 3. That
entry indicates that MN.sub.h,Pq had connected with foreign
Host.sub.B1, but is no longer connected to network 12. Thus, no
connection of MN.sub.h,Pq is illustrated with any Host in FIG. 1.
Such an entry will also indicate to a CN that the MN has not
established a connection with another host, since the CN will only
contact network 12 via the VA of MN.sub.h,Pq, namely
MN.sub.h,Pq@Host.sub.B1, if MN.sub.h,Pq's home network's NAT's MHD
record has not been updated. If a CN attempts to communicate with
the visiting node at that time and is referred to the visited
network's NAT by the MN's home Host's NAT, a binding will not be
established and the communication will fail.
[0037] When a MN's home network's NAT receives a communication to
change the binding information for the MN from one foreign NAT to
another, it preferably sends a message to the first foreign NAT
reflecting the the MN is no longer visiting that NAT's network, so
that the visiting node record can be deleted from the first foreign
NAT's MHD. Such a message is preferably also sent, when a MN
returns to its home network after visiting other networks.
[0038] The CN never needs to know the current location of the MN.
The CN only needs to be aware of the static, default binding based
on a MN's home address (HA) and home network's global address. This
arrangement saves the flurry of registration messages from being
sent over the global Internet.
[0039] The tight coupling of the MHDs to the NATs means that an IP
data packet does not have to travel first to the home network. The
packet can be tunneled directly to the foreign network where the MN
is located. This avoids the infamous triangle routing problem.
[0040] The micro-mobility protocol for MNs roaming across multiple
foreign networks (FNs) starts with the CN's NAT trying to establish
a binding with the MN's home network's NAT. The process fails, when
the status-bit in the MN's home network's NAT's MHD is a 1. This
indicates that the MN is not currently in its home network (HN); it
is in a FN. The FN has assigned a VA to the MN which is stored in
the MN's home network's NAT's MHD along with the static global
address of the FN. That binding data is sent back to the CN's NAT
and the CN's NAT then establishes binding with the FN's NAT. The
rest of the protocol then proceeds the same way as if the MN were
connected with a host in its home network.
[0041] When during a communication with a CN, a MN moves from one
foreign network FN.sub.1 to a different to a different foreign
network FN.sub.2, the entries for the MN in the MHD of FN.sub.1 are
preferably set 0, NULL, NULL when the MN loses contact with the
FN.sub.1. When the MN then moves to the different FN.sub.2, it
communicates with FN.sub.2 via a host, Host.sub.2, associated with
the NAT of FN.sub.2, NAT-FN.sub.2. The MN is assigned a VA of
MN@Host.sub.2 such that the entries for that VA in the MHD of
NAT-FN.sub.2 are set to 0, MN@Host.sub.2, NULL. The binding data
(MN@Host.sub.2, NAT-FN.sub.2) is sent to the MN's home network's
NAT and the CN's NAT. A new binding is established between the CN's
NAT and NAT-FN.sub.2. The rest of the protocol then proceeds as
described above.
[0042] When during a communication with a CN, a MN moves from a
foreign network FN.sub.1 to back to its home network HN, the entry
for the MN in the MHD of the NAT of FN.sub.1 is preferably set 0,
NULL, NULL when the MN loses contact with the FN.sub.1. When the MN
then moves to its HN, it communicates with its HN via a host,
Host.sub.HN, associated with its HN's NAT, NAT-HN. Note that
Host.sub.HN may or may not be the MN's home host, Host.sub.Home. In
its HN's NAT's MHD, the MN already has a data record for its HA of
MN@Host.sub.Home. That record is preferably then changed to set the
associated data fields to 0, MN@Host.sub.HN, NULL. The binding data
(MN@Host.sub.Home, NAT-HN) is sent to the CN's NAT. A new binding
is established between the CN's NAT and NAT-HN. The rest of the
protocol then proceeds as described above.
[0043] The CN's NAT in the above cases would normally be the CN's
home network's NAT. However, if the CN is a MN which is visiting a
FN, the CN's NAT is the NAT of the FN being visited.
[0044] Other variations and alternatives will be recognized by
those of ordinary skill in the art as within the scope of the
invention are intended to be included herein.
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