Electrical computers and digital processing systems: multicomput – Network computer configuring – Initializing
Reexamination Certificate
2000-04-27
2002-01-08
Rinehart, Mark H. (Department: 2152)
Electrical computers and digital processing systems: multicomput
Network computer configuring
Initializing
C370S329000
Reexamination Certificate
active
06338087
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a method of setting up a temporary local area network (also referred to as a “LAN”) generally set up solely of terminals and not having a fixed backbone network, a method of communicating using this network, and a terminal for use in the network.
BACKGROUND OF THE INVENTION
Known examples of LAN configurations include a LAN connected to a fixed backbone network via a router of the kind described in document (1) “Interconnections: Bridges and Routers” by Radia Perlman, Addison-Wesley, 1992 (this LAN is referred to as a “backbone-connected LAN”), and a LAN temporarily set up solely of terminals and not connected to a backbone network via a router, as described in document (2) “Routing in Ad Hoc Networks of Mobile Hosts” by David B. Johnson, Proceedings of the Workshop on Mobile Computing Systems and Applications, pp. 158~163, IEEE Computer Society, Santa Cruz, Calif., December 1994 (this LAN is referred to as an “ad hoc LAN”).
These LANs have different features and the circumstances in which they are used differ in the following way: In the case of the backbone-connected LAN, communication is carried out among terminals and servers connected to other LANs mutually connected by a fixed backbone network. A backbone-connected LAN is suited to a regularly performed operation such as the sending and receiving of electronic mail for a daily business.
An ad hoc LAN, on the other hand, brings together terminals having a communication function and only these terminals communicate with one another. This LAN is useful in a scenario such as a conference in which the participants gather together bringing their terminals with them.
The configurations of a backbone-connected LAN and ad hoc LAN are illustrated in
FIGS. 8 and 9
, respectively.
As shown in
FIG. 8
, backbone-connected LANs
1010
,
1020
are connected to a backbone network
1000
. Though only two backbone-connected LANs are depicted in
FIG. 8
, there are instances where three or more of these LANs are thus connected.
The internal construction of the backbone-connected LANs will be described taking the LAN
1010
as an example.
As shown in
FIG. 8
, the backbone-connected LAN
1010
is connected to the backbone network
1000
via a router
1005
. Conceivable transmission media are a physical wire as at
1007
or a wireless link as at
1006
. Examples of terminals used within the backbone-connected LAN are a wired terminal
1004
connected via the wire transmission medium
1007
and wireless terminals
1001
,
1002
connected via the wireless transmission medium
1006
. The wireless terminals
1001
,
1002
are capable of communicating with the wired terminal
1004
and router
1005
, which are connected to the wired medium
1007
, via a wireless base station
1003
.
Further, the terminals in the backbone-connected LAN
1010
communicate with terminals connected to another backbone-connected LAN, such as the backbone-connected LAN
1020
, via the router
1005
and backbone network
1000
.
The ad hoc LAN, on the other hand, is constructed as shown in FIG.
9
.
FIG. 9
schematically illustrates the manner in which two ad hoc LANs
1100
and
1110
exist. Though only two ad hoc LANs are depicted in
FIG. 9
, there are instances where three or more of these LANs may exist.
As shown in
FIG. 9
, the ad hoc LANs
1100
and
1110
include three wireless terminals
1101
,
1102
,
1103
and
1111
,
1112
,
1113
, respectively. The wireless terminals within each ad hoc LAN communicate with one another via wireless transmission media
1104
and
1114
, respectively, but there is no communication between the ad hoc LANs. Though
FIG. 9
illustrates an arrangement in which the ad hoc LANs use wireless transmission media, it is possible to adopt an arrangement in which only wired transmission media are used or one in which both wired and wireless transmission media are employed.
A method relying upon connection by a router and a method relying upon connection by a bridge are known as methods of connecting different LANs. For example, see the document (1) above (“Interconnections: Bridges and Routers” by Radia Perlman, Addison-Wesley, 1992).
Such arrangements are illustrated in
FIGS. 10 and 11
, which show the manner in which a terminal A (
1121
) and a terminal B (
1131
) communicate with each other in a case where different LANs comprising respective transmission media
1120
,
1130
are interconnected via a relay node
1125
(
FIG. 10
) or
1126
(FIG.
11
).
FIG. 10
illustrates connection by router, in which the relay node
1125
functions as the router. In this case the relay node
1125
is such that processing for transferring packets used in communication between the terminal A and the terminal B is executed in the network layer.
FIG. 11
, on the other hand, illustrates connection by bridge, in which the relay node
1126
functions as the bridge. In this case the relay node
1126
is such that processing for transferring packets used in communication between the terminal A and the terminal B is executed in the data link layer.
The router arrangement is implemented using addresses in the network layer. Though transfer processing presents a heavy load, flexible control is possible.
With the bridge arrangement, on the other hand, only simple transfer control can be carried out but the transfer processing is simple.
Multicast communication is known as a communication scheme in which bandwidth is utilized effectively. According to multicast communication, a plurality of parties are defined as a group, and in case of communication within the group, data is not transmitted to the individual parties but is instead multicast to the defined group by a single transmission. For a description of multicasting, see document (3) “Mbone: Interactive Multimedia on the Internet” by Vinay Kimar, New Riders Publishing, 1995 etc.
Multicasting is implemented by defining a multicast address for each multicast group. In a case where data is transmitted to a certain multicast group, the data is transmitted with the multicast address of this group serving as the destination address. A terminal participating in the multicast group receives the data that has been transmitted using the multicast address of the group as the destination of the transmission. The packet format used in such multicast communication is as shown in FIG.
14
. As shown in
FIG. 14
, the format includes a network layer header
1300
and higher layer data
1301
. The network layer header
1300
includes a multicast address as the destination and a transmitting terminal address as the address of the transmitting party.
DISCUSSION ON THE RELATED ART
In the course toward the prevent invention, the following problems have been encountered.
From the user standpoint, it would be desirable to be able to simultaneously perform, through use of a single terminal, daily communication such as email communication using a backbone-connected LAN and temporary communication provided by an ad hoc LAN. However, a backbone-connected LAN and an ad hoc LAN are separate, independent entities and one terminal cannot be connected to both LANs at the same time. This means that two different terminals are required in a case where the user wishes to communicate with both a backbone-connected LAN and an ad hoc LAN.
Conventional methods of connecting two different LANs include the bridge connection and the router connection, as illustrated in
FIGS. 10 and 11
.
If a terminal possesses a function for implementing a connection between LANs, it is possible for the terminal to be connected to both a backbone-connected LAN and an ad hoc LAN. However, most terminals have a construction of the kind shown in FIG.
12
.
As illustrated in
FIG. 12
, network layer software
211
performs an exchange of data with a device driver
1200
, which is dependent upon a transmitter/receiver
1201
that executes the processing of a data link layer and physical layer, via a standard interface (interface
1
in
FIG. 12
) such as one in accordance with the NDIS (Network Driver Interface Stan
NEC Corporation
Rinehart Mark H.
Vu Thong
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