Electrical computers and digital processing systems: multicomput – Computer-to-computer data addressing
Reexamination Certificate
1999-05-27
2002-05-21
Maung, Zarni (Department: 2154)
Electrical computers and digital processing systems: multicomput
Computer-to-computer data addressing
C709S238000, C709S227000
Reexamination Certificate
active
06393488
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the field of network communications. More particularly, the present invention relates to supporting internet protocol (IP) subnets with network address translators.
BACKGROUND OF THE INVENTION
As networks and the internet gain in popularity and users, the sheer number of devices coupled to various networks and to the internet have increased drastically. As a result, the vast number of different networks that communicate with each other but are under separate control and administration increases the difficulty of assigning each device a unique identifying address. One approach that effectively expands address capacity limitation is to provide address translation through a network address translator (NAT).
Typically a NAT facilitates the transmission of communications from one network to another network by performing an address translation for a device coupled thereto. In so doing, multiple devices effectively share a common address. That is, the NAT assigns an IP address to each of the devices coupled thereto. However, the addresses assigned by the NAT are not publicly-administered, routable, unique addresses. As a result, the are used only “behind” the NAT and are not passed beyond the NAT.
FIG. 1
is an example of a prior art network
100
. Network
100
comprises a first network (e.g. a LAN), a second network (e.g. a LAN), and PC
131
all coupled to each other via phone system
140
. The first LAN comprises PC
111
, PC
112
, and PC
113
, all of which are coupled to network address translator (NAT)
115
. The second LAN comprises PC
121
, PC
123
, and server
122
all of which are coupled to NAT
125
. NAT
115
and NAT
125
are coupled to phone system
140
and provide translation between addresses of the first and second networks.
Unfortunately, the use of conventional NATs is not without problems. For example, because NATs may utilize similar software, two separate NATs may assign the same IP address to device coupled thereto. As an example, NAT
115
of Prior Art
FIG. 1
, may, for example, assign PC
111
an IP address of
192
.
168
.
1
.
2
, assign PC
112
an IP address of
192
.
168
.
1
.
3
, and assign PC
113
an IP address of
192
.
168
.
1
.
4
. Similarly, NAT
125
of Prior Art
FIG. 1
, may, for example, assign PC
121
an IP address of
192
.
168
.
1
.
2
, assign PC
123
an IP address of
192
.
168
.
1
.
3
, and assign server
122
an IP address of
192
.
168
.
1
.
4
. Because NATs
115
and
125
utilize similar address assigning schemes PC
111
and PC
121
now have the same address assigned thereto by their respective NAT. Likewise, PC
112
and PC
123
have the same address assigned thereto by their respective NAT, and PC
113
and server
122
now have the same address assigned thereto by their respective NAT. As a result, address conflicts may arise when, for example, PC
121
wishes to send data to PC
111
. Because PC
121
and PC
111
share the same address, a subnet address conflict arises and the data cannot be appropriately handled. Similarly, PC
121
may wish to send data to PC
112
. Because PC
112
and PC
123
have the same address, the data intended for PC
112
is instead handled as though it was intended for PC
123
.
In one attempt to overcome such subnet address conflicts, prior art approaches require a user to examine all of the NAT-assigned IP addresses for each of the various NATs. The user must make sure that each device coupled to a NAT has a unique address assigned thereto. This process is usually relatively complicated and tedious. In many instances, the user is required to understand the intricacies of communication frame protocols and construct complicated and extensive tables that map types of communication frames to NAT ports and uniquely defined IP addresses. Furthermore, a solution to the above-listed problems should be compatible with existing NAT systems and designs.
Thus, a need exists for a network address translator system and method which is able to resolve NAT-based subnet address conflicts. Still another need exists for a network address translator system and method which meets the above need and which eliminates the need for tedious user examination of all NAT-assigned IP addresses for each of the various NATs. Yet another need exists for a network address translator system and method which meets the above-listed needs and which is compatible with existing network address translator devices.
SUMMARY OF THE INVENTION
The present invention provides a network address translator system and method which is able to resolve NAT-based subnet address conflicts. The present invention further provides a network address translator system and method which accomplishes the above achievement and which eliminates the need for tedious user examination of all NAT-assigned IP addresses for each of the various NATs. The present invention also provides a network address translator system and method which accomplishes the above-listed achievements and which is compatible with existing network address translator devices.
In one embodiment of the present invention, a first NAT is used to assign an address to a first device which is coupled to the first NAT. Next, the present embodiment using a second NAT to assign an address to a second device coupled to the second NAT. Additionally, in the present embodiment, the second NAT automatically assigns an address to a link coupling the first NAT and the second NAT. The second NAT then assigns a second address to the second device. The second address is related to the address of the link coupling the first NAT and the second NAT. In so doing, the present invention insures that the second device has a second address associated therewith wherein the second address is different from the address of the first device. As a result, the present embodiment is able to resolve NAT-based subnet address conflicts. The present embodiment also eliminates the need for tedious user examination of all NAT-assigned IP addresses for each of the various NATs. Furthermore, the present embodiment is compatible with existing network address translator devices.
These and other objects and advantages of the present invention will no doubt become obvious to those of ordinary skill in the art after having read the following detailed description of the preferred embodiments which are illustrated in the various drawing figures.
REFERENCES:
patent: 6058431 (2000-05-01), Srisuresh et al.
patent: 6108330 (2000-08-01), Bhatia et al.
patent: 6128664 (2000-10-01), Yanagidate et al.
patent: 6266707 (2001-07-01), Boden et al.
patent: 6269099 (2001-07-01), Borella et al.
patent: 6304908 (2001-10-01), Kalajan
patent: 6327662 (2001-12-01), Araujo
3Com Corporation
Maung Zarni
Wagner , Murabito & Hao LLP
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