Method and apparatus for bridging wireless LAN to a wired LAN

• US 5,812,531 A
• Filed: 07/24/1995
• Issued: 09/22/1998
• Est. Priority Date: 07/29/1994
• Status: Expired due to Term

• Current Assignee: NETGEAR, Inc.
• Original Assignee: International Business Machines Corporation
• Inventors: Reissner, Peter E., Cheung, Roger Y. M.
• Primary Examiner(s): Jung, Min
• Application Number:
  US08/505,928
• Time in Patent Office: 1,156 Days
• Field of Search: 370/94.1, 370/94.3, 370/95.1, 370/85.13, 370/85.14, 370/254, 370/255, 370/256, 370/257, 370/400, 370/401, 370/410, 370/312, 370/328, 370/331, 370/332, 370/338, 455/33.1, 455/33.2, 455/33.4, 455/438, 455/439, 455/445, 395/200.5, 395/200.51, 395/200.68
• US Class Current: 370/255
• CPC Class Codes: H04W 40/24 Connectivity information management, e.g. connectivity discovery or connectivity update
• CPC Class Codes: H04W 84/20 Master-slave selection or change arrangements
• CPC Class Codes: H04W 92/02 Inter-networking arrangements

Abstract

An internetworking node for providing internetworking services for mobile wireless nodes is disclosed. Each mobile wireless node is registered with at the most one internetworking node. Each mobile wireless node emits a topology broadcast identifying itself and other nodes it has heard. Each internetworking node uses these topology broadcasts to construct a table tracking each mobile node within its range, whether that mobile node is registered to that internetworking node and also a list of which other nodes that mobile wireless node can hear. The internetworking node determines which of these wireless nodes it will register. The internetworking node will then act for all wireless nodes registered to it in relaying messages between wireless nodes or between a wired LAN and the wireless nodes.

Claims

1. An internetworking node for use in a network including a plurality of wireless nodes and wired nodes, said internetworking node comprising:

means to send data to the wireless nodes and to receive data from the wireless nodes;

means to send data to the wired nodes and to receive data from the wired nodes;

means to recognize and store received data which comprises messages from at least one of the wireless node containing information as to the network address of said at least one of the wireless node and other nodes from which said at least one of the wireless node can receive data;

means to cause said sending means periodically to broadcast information as to the network address of the internetworking node;

means to intercept data transmission from a first wireless node to a second wireless node;

means to access stored messages from said second wireless node;

means to determine from said stored messages whether said second wireless node had received data from the first wireless node within a period of time prior to a last broadcast message sent by the second wireless node, and means for forwarding the intercepted data transmission if the message indicates that the second wireless node has not received data from the first wireless node during the period of time.

2. A method for internetworking between wireless nodes comprising the steps of:

(a) sending and receiving data between wireless nodes and internetworking nodes;

(b) recognizing and storing received data which comprises a message from at least one other wireless node containing information as to the address of such other wireless node,

(c) broadcasting, by each wireless node, at the end of a period its own network address and a list of the network addresses of any other wireless nodes from which it has received a message within the period;

(d) clearing, by each wireless node, the entire list of network addresses after performance of step (c);

(e) recognizing and storing, by said internetworking nodes received data which comprises broadcast messages from wireless nodes containing information as to the network address of each such node and the other nodes from which it has received said message within said period;

storing the address of wireless nodes for wireless nodes which an internetworking node has received a broadcast during the period;

storing the list which each of the said wireless node also broadcasts; and

registering, some, none, or all of these wireless nodes.

3. A method as claimed in claim 2, comprising additional steps of establishing a hierarchy of internetworking nodes, and causing each internetworking node not to register wireless nodes which have broadcast a message confirming that they have received identification information from that internetworking node, if such wireless node also broadcasts a message showing that it has received identification information from a internetworking node more senior in the hierarchy.

4. A method as claimed in claim 2, comprising additional steps of

recognizing data transmitted by a registered wireless node and which is addressed to a node which is not listed;

and

retransmitting of such data by the internetworking node by wireless transmission if the destination node is a wireless node from which the internetworking node has received a broadcast during the period and retransmitting such data on the wired LAN otherwise.

5. A wireless node for use in a network comprising:

means in said wireless node to send messages to other wireless nodes and receive messages from said other wireless nodes;

a memory for maintaining a list of network addresses of other wireless nodes within a predetermined range;

means to recognize and store in said memory the network addresses of other wireless nodes contained in the receive messages;

means to cause said sending means at the end of a period to broadcast its own address and the list of network addresses;

means for deleting the entire list of network addresses maintained in said memory after broadcasting its own address and the list of network addresses; and

means for reconstructing a new list of network addresses, in the memory, from messages received from the nodes in an ensuing period.

6. An internetworking node for use in a network including a plurality of wireless nodes including:

means to send messages to the wireless nodes and to receive messages from the wireless nodes;

a memory for storing a topology table, said topology table including a first tier column in which network addresses of wireless nodes transmitting topology broadcast messages received by said at least one internetworking node are being stored, a second tier column for storing network addresses of other wireless nodes contained in said topology broadcast messages and an indicia column indicating if the network address of a wireless node is registered to said internetworking nodes;

means to analyze the topology broadcast messages and enter in said topology table the network addresses of the wireless node transmitting the topology broadcast message and network addresses of other nodes contained in the topology broadcast messages; and

means for analyzing the topology table or broadcast messages received at said internetworking node to determine if a sending wireless node is to be registered or not registered to said internetworking node.

7. The internetworking node of claim 6 further including means for marking registration status of wireless node in the indicia column.

8. The internetworking node of claim 6 further including means for broadcasting the address of the internetworking node.

9. An internetworking node as claimed in claim 6 further comprising means to cause said internetworking node sending means at least once during each said period to broadcast identification information identifying the internetworking node.

10. The method as claimed in claim 9 further comprising the following steps carried out by the internetworking node:

storing the address of wireless nodes for wireless nodes which the internetworking node has received a broadcast during the period;

storing the list which each of the said wireless nodes also broadcasts; and

registering, some, none, or all of those wireless nodes.

11. An internetworking node as claimed in claim 10 further including means for marking in the indicia column registration status of the sending wireless node;

means for recognizing messages on the wired network which are addressed to a node which has been registered; and

means for wireless retransmission of such messages to that node.

12. An internetworking node as claimed in claim 10 further including means to recognize information transmitted by a registered wireless node to a wireless node which is not listed in the topology table;

and

means for causing the means which send messages to the wireless node to send said information to the wireless node which is not listed in the topology table if the internetworking node had received a broadcast from the wireless node, not listed in the topology table, within a specified time interval.

13. The internetworking node as claimed in claim 12 further including means to send messages to the wired LAN and to receive messages from the wired LAN with said means being operable to send information to the wired LAN if said information was not sent by wireless transmission.

14. A method for communicating between wireless nodes comprising the steps of:

a) sending and receiving messages between the wireless nodes;

b) maintaining in at least one of a first group of the wireless nodes, a node address list identifying addresses of wireless nodes obtained from broadcast messages received in said selected ones of wireless nodes;

c) periodically broadcasting from each of the selected ones of the wireless nodes a topology broadcast message containing its own address and addresses of nodes recorded in its node address list;

d) upon conclusion of a broadcast, each broadcasting wireless node deleting its entire node address list;

e) upon conclusion of a deletion, each wireless node reconstructing a new node address list from received broadcast messages;

f) building and maintaining in at least one of a second group of wireless nodes a topology table containing information on selected ones of wireless nodes within a predetermined range of said at least one of said second group of wireless nodes and information on other wireless nodes which the selected ones of wireless nodes can hear; and

said at least one of the second group of wireless nodes using the information in its topology table to determine whether to intervene or not intervene in delivery of messages between wireless nodes.

15. The method of claim 14 further including the step of:

structuring the topology table to include a first tier column in which addresses of the wireless nodes within the predetermined range of said at least one of said second group of wireless nodes are placed, a second tier column in which addresses of wireless nodes within hearing distance of wireless nodes in the first tier column are placed and a registration column having identifying wireless node register or not register to the at least one of the second group of wireless nodes.

16. The method of claim 15 further including the steps of selecting the addresses stored in the first tier column and the second tier column from received topology broadcast messages;

and

correlating information in the topology broadcast messages and information in the topology table to determine the registration status of a wireless node.

17. A network including:

a wired LAN;

a plurality of wireless nodes;

a plurality of internetworking nodes connected to the wired LAN;

wherein at least one of the internetworking nodes includes means to send messages to the wireless nodes and to receive messages from the wireless nodes;

a memory for storing a topology table, said topology table including a first tier column in which network address of wireless nodes transmitting topology broadcast messages received by said at least one internetworking node are being stored, a second tier column for storing network addresses of other wireless nodes contained in said topology broadcast messages and an indicia column indicating if the network address of a wireless node is registered to said internetworking nodes;

means to analyze the topology broadcast messages and enter in said topology table the network addresses of the wireless node transmitting the topology broadcast message and network addresses of other nodes contained in the topology broadcast messages;

means for analyzing the topology table or broadcast messages received at said internetworking node to determine if a sending wireless node is to be registered or not registered to said internetworking node;

means for establishing a hierarchy of internetworking nodes; and

means for causing said at least one internetworking node not to register wireless nodes which have broadcast a message confirming that they have received identification information from that internetworking node, if such wireless node also broadcasts a message showing that it has received identification information from an internetworking node more senior in the hierarchy.