This application claims the benefit of Korean Patent Application No. 10-2005-31505, filed on Apr. 15, 2005, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
1. Field of the Invention
Aspects of the invention relate to a method and an apparatus to route frames in an extended wireless local area network (LAN) environment, and, more particularly, to a method and apparatus to form an effective transmission route, grouping wireless access points, and to prevent frames from being redundantly transmitted in an extended wireless LAN environment into which the wireless access points are introduced.
2. Description of the Related Art
A repeater having wired and wireless interfaces is typically required to transfer data from a wired network to a mobile terminal connected to a wireless network. An access point (AP) defined by the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard generally plays the role of a repeater in a LAN.
However, an extended wireless LAN, such as a wireless mesh network, in which a mobile node is separated from a wired network and can route frames is not specified. Mobile nodes can communicate the frames in the extended wireless LAN and form an ad hoc network. In this regard, where the frames are broadcasted, a broadcast storm in which the frames are repeatedly transmitted in a loop can occur. Such a repetition of the loop can be prevented by redesigning the topology, such as a spanning tree, but can ineffectively set a frame transfer route.
Further, similar to the LAN illustrated in
Several aspects and exemplary embodiments of the invention provide a method and an apparatus to group wireless access points, to set an effective transmission route, and to prevent frames from being redundantly transmitted in an extended wireless LAN environment.
According to an aspects of the invention, there is provided a method of routing a frame received over a wired network to a wireless network including mobile nodes (MNs) having a frame routing function, by a routing device to interconnect both the wired and wireless networks, the method including: detecting destination address information included in the frame; comparing the detected destination address information with address information of MNs belonging to a group which the routing device manages; and selectively transferring the frame to the MNs belonging to the group based on the address information comparison.
According to aspects of the invention, there is also provided a computer-readable storage medium having embodied thereon a computer program to execute by a processor a method of routing a frame received over a wired network to a wireless network including mobile nodes (MNs) having a frame routing function, by a routing device to interconnect both the wired and wireless networks, the method of routing the frame embodied in the program including: detecting destination address information included in the frame; comparing the detected destination address information with address information of MNs belonging to a group which the routing device manages; and selectively transferring the frame to the MNs belonging to the group based on the address information comparison.
Further, according to aspects of the invention, there is provided an apparatus to route a frame between a wireless network including mobile nodes (MNs) having a frame routing function and a wired network, the apparatus including: a comparator to compare address information of MNs belonging to a group which the apparatus manages with destination address information included in the frame received over the wired network; and a transmitter to selectively transfer the received frame to the MNs belonging to the group based on the address information comparison.
Also, according to aspects of the invention, there is provided a method of routing a broadcast frame in a wireless network, the method including: receiving at least one group identifier (GID), to determine a transfer range of a broadcast frame from an apparatus to relay the broadcast frame between the wireless network and a wired network, and selecting a GID of the received one or more group identifiers (GIDs); receiving the broadcast frame; detecting a GID included in the received broadcast frame and comparing the detected GID with the selected GID; and selectively transferring the broadcast frame based on the GID comparison.
According to aspects of the invention, there is also provided a computer-readable storage medium having embodied thereon a computer program to execute by a processor a method of routing a broadcast frame in a wireless network, the method of routing the broadcast frame embodied in the program including: receiving at least one group identifier (GID) to determine a transfer range of a broadcast frame from an apparatus to relay the broadcast frame between the wireless network and a wired network and selecting a GID of the received one or more GIDs; receiving the broadcast frame; detecting a GID included in the received broadcast frame and comparing the detected GID with the selected GID; and selectively transferring the broadcast frame based on the GID comparison.
Further, according to aspects of the invention, there is provided a method of routing a broadcast frame in a wireless network including mobile nodes (MNs) having a frame routing function, the method including: generating a group identifier (GID) to determine a transfer range of a broadcast frame and broadcasting the broadcast frame; receiving the broadcast frame; comparing a GID included in the received broadcast frame with the generated GID; and selectively transferring the broadcast frame based on the GID comparison.
Additionally, according to aspects of the invention, there is provided a computer-readable storage medium having embodied thereon a computer program to execute by a processor a method of routing a broadcast frame in a wireless network including mobile nodes (MNs) having a frame routing function, the method of routing the broadcast frame in the wireless network embodied in the program including: generating a group identifier (GID) to determine a transfer range of a broadcast frame and broadcasting the broadcast frame; receiving the broadcast frame; comparing a GID included in the received broadcast frame with the generated GID; and selectively transferring the broadcast frame based on the GID comparison.
Also, according to aspects of the invention, there is provided an apparatus to route a frame in a wireless network, the apparatus including: a receiver to receive at least one group identifier (GID) to determine a transfer range of a broadcast frame from an apparatus to relay the broadcast frame between the wireless network and a wired network; a selector to select a GID of the received one or more group identifiers (GIDs); a comparator to compare a GID included in the broadcast frame to the GID received by the receiver, if the broadcasting frame is received; and a transmitter to transfer the broadcast frame based on the GID comparison.
Additional aspects and/or advantages of the invention are set forth in the description which follows or are evident from the description, or can be learned by practice of the invention.
These and/or other aspects and advantages of the invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
Reference will now be made in detail to embodiments of the invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below in order to explain aspects of the invention by referring to the figures, with well-known functions or constructions not necessarily being described in detail.
The first repeater 210 and the second repeater 220 repeat frames between the wired network 203 and the wireless network 204, and interface two different environments since the wired network 203 does not follow the IEEE 802.11 protocol in the wireless LAN environment. The first repeater 210 and the second repeater 220 are referred to as portals in the IEEE 802.11 protocol, and are generalized terms for the portals. A first mobile node (MN) 230 (MN1), a second MN 240 (MN2), a third MN 250 (MN3), a fourth MN 260 (MN4), and a fifth MN 270 (MN5) are introduced from the extended wireless LAN environment, and route the frames based on a MAC address, which is a data link layer address of an open systems interconnection (OSI) reference model, and can communicate with each other over the wireless network 204. The first MN 230 (MN1), the second MN 240 (MN2), the fourth MN 260 (MN4), and the fifth MN 270 (MN5) typically do not include a basic service set (BSS), and thus they are not referred to as wireless access points (APs). However, the third MN 250 (MN3) is an AP including a BSS 290 to which a station 280 belongs.
The frames transmitted from the router 200 or the host 202 and received by the first and second repeaters 210 and 220 are forwarded based on the MAC address. If a frame that is transmitted from the Internet 201 to the station 280 reaches the wired network 203, the first repeater 210 and the second repeater 220 can forward the frame to the first MN 230 (MN1), the second MN 240 (MN2), the third MN 250 (MN3), the fourth MN 260 (MN4), and the fifth MN 270 (MN5). The first MN 230 (MN1), the second MN 240 (MN2), the third MN 250 (MN3), the fourth MN 260 (MN4), and the fifth MN 270 (MN5) can form a wireless ad hoc network so that a transfer range is determined according to a topology structure, other than radio wave reach distances of the first repeater 210 and the second repeater 220, to generate various transfer routes. Since a frame of a link layer does not include a field to determine whether the frame is repeatedly transmitted, if the station 280 broadcasts the frame, a loop can be generated as indicated by the arrows in
Also, where a proxy address resolution protocol (ARP) is used, the first repeater 310 and the second repeater 320 do not store MAC addresses of all mobile stations, but store the MAC addresses of the MNs respectively belonging to the groups A and B. Where the first repeater 310 broadcasts an ARP frame, the third MN 350 (MN3) responds to the ARP frame instead of the station 351, and the first repeater 310 forwards the ARP frame to the third MN 350 (MN3). In this regard, each of the first MN 330 (MN1), the second MN 340 (MN2), the third MN 350 (MN3), the fourth MN 360 (MN4), and the fifth MN 370 (MN5) store MAC addresses of mobile stations respectively belonging to a BSS of the MN.
Where a mobile station belonging to a mobile node broadcasts a frame, and if each of the MNs stores a group ID that discriminates groups of the MNs, a broadcast storm typically does not occur. More specifically, if the station 351 belonging to the group A broadcasts the frame, the fourth MN 360 (MN4) belonging to the group B does not forward the frame transmitted by the third MN 350 (MN3) and disregards the frame, so that a repetitive transfer loop is typically not generated. In that the frame must include the group identifier (ID), a station or an MN must write the group ID to the frame. Further, since a sixth MN 390 (MN6) can be linked with the first repeater 310 and the second repeater 320, the first repeater 310 and the second repeater 320 must store the group ID. In this regard, the second repeater 320 forwards a broadcasted frame over the wired network 380 and disregards a broadcast frame received from the sixth MN 390 (MN6).
The advertisement frame generator 420 generates an advertisement frame including a MAC address of the repeater 400 and broadcasts the advertisement frame. If the MN 450 receives the advertisement frame, and the MN 450 determines to join a group including the repeater 400, and the MN 450 sends a response frame including a MAC address of the MN 450, the group information storage unit 425 stores the MAC address of the MN 450. Where the MN 450 receives the advertisement frame but does not send a response frame, the group information storing unit 425 can obtain the MAC address of the MN 450 that has joined the group. In this regard, the repeater 400 can obtain MAC addresses of MNs or mobile stations that join the group of the repeater 400 based on an orientation address information field of a data frame transmitted from the MNs or mobile stations. Also, in this regard, where an MN changes groups, the repeaters typically are informed of such a change of groups, such as further discussed with reference to
The group information storage unit 425 stores address information related to the MNs that have joined the group. The address information includes MAC addresses of stations. Also, if a proxy ARP is used, the address information includes MAC addresses of MNs, as described. The group ID generator 430 generates the group ID used to discriminate groups, stores the group ID in a database associated with the repeater 400, such as a suitable memory, and transmits the group ID of a group member, via the wireless network interface 415. However, the group ID can be included in the advertisement frame generated by the advertisement frame generator 420. Also, the group information storage unit 425, such as a suitable memory, can store the group ID.
The processor 440 includes a transmitter 443, a comparator 444, and a determiner 445. The processor 440 can be any suitable processing device, such as a processor, microprocessor or an application specific integrated circuit (ASIC), with associated memory and software or programming, to control the operations of the repeater 400. If the processor 440 receives a frame from the wired network via the wired network interface 410, the comparator 444 compares destination address information of the frame to the MAC address stored in the group information storage unit 425. Where the MAC address and the destination address information are identical to, or corresponds to, each other, the transmitter 443 forwards the frame to a mobile station. Where the MAC address and the destination address information are not identical to, or do not correspond to, each other, the frame is disregarded.
If a broadcast frame is received, the comparator 444 compares a group ID included in the broadcast frame with the group ID generated by the group ID generator 430. If the group IDs are identical, or correspond, to each other, the transmitter 443 forwards the broadcast frame. If the group IDs are not identical, or do not correspond, to each other, the broadcast frame is disregarded. However, broadcast frames transmitted over the wired network typically are forwarded without comparing both group IDs. In this regard, the determiner 445 determines whether the processor 440 receives the broadcast frame over the wired network or the wireless network.
The processor 470 of the MN 450 includes a receiver 471, a comparator 472, a selector 476, a transmitter 473, a fabricator 474, and a determiner 475. The processor 470 can be any suitable processing device, such as a processor, microprocessor or an application specific integrated circuit (ASIC), with associated memory and software or programming, to control the operations of the MN 450. The determiner 475 receives the advertisement frame from the repeater 400, determines whether to join the group including the repeater 400, and informs the transmitter 473 of its determination. The transmitter 473 transmits a response frame to the MAC address of the repeater 400 included in the advertisement frame.
The receiver 471 receives a group ID from the repeater 400 via the wireless network interface 455. The group ID storage unit 460 stores the group ID. If the receiver 471 receives two or more group IDs, the selector 476 selects one of the group IDs so that no MN typically should belong to two or more groups simultaneously. If the receiver 471 receives the broadcast fame via the wireless network interface 455, the comparator 472 compares a group ID included in the broadcast frame with the group ID of the group of the MN 450 stored in the group ID storage unit 460. If the group IDs are identical to, or correspond to, each other, the transmitter 473 forwards the broadcast frame. If the group IDs are not identical, or do not correspond, to each other, the broadcast frame is disregarded. Also, if the receiver 471 receives a broadcast frame that does not include a group ID, and the fabricator 474 determines that the broadcast frame is transmitted from a mobile station within the BSS managed by the MN 450, the fabricator 474 writes the group ID of the group of the MN 450 to the broadcast frame, and forwards the broadcast frame.
The MN receives the broadcast frame (Operation 630), extracts a group ID included in the broadcast frame and analyzes the extracted group ID (Operation 640), and determines whether a group ID exists (Operation 650). If no group ID exists, and the MN determines that a mobile station within a BSS managed by the MN has broadcasted the frame, the MN writes a group ID of the group of the MN to the broadcast frame (Operation 680), and forwards the broadcast frame (Operation 690). If a group ID exists, the MN compares the group ID of the group of the MN with the extracted group ID (Operation 660). If the group IDs are identical, or correspond, to each other, the MN forwards the broadcast frame (Operation 690). If the group IDs are not identical to, or do not correspond to, each other, the MN disregards the broadcast frame (Operation 670).
In this regard, if a fourth MN 750 (MN4) of the group B analyzes a group ID of the broadcast frame transmitted from a second MN 720 (MN2) and determines that the broadcast frame is not transmitted from the group B, the broadcast frame is not forwarded. The broadcast frame is forwarded via a second repeater 740 over a wired network. Finally, since the broadcast frame forwarded by the fifth MN 760 (MN5) includes a group ID of the group B, the third MN 730 (MN3) disregards the broadcast frame.
Therefore, the third MN 730 (MN3) transmits a broadcast frame to the second repeater 740 in order to join the group B. In this regard, a first repeater 700 deletes the third MN 730 (MN3) from a routing table, which is a MAC address information list of group members of the first repeater 700, and the second repeater 740 or the third MN 730 (MN3) informs the first repeater 700 of the group change.
Referring to
According to the aspects of the invention, a repeater groups MNs and manages the grouped MNs in an extended wireless LAN environment. Therefore, where an MN communicates with two or more repeaters directly or indirectly, a route is typically set such that a frame is received via a repeater, to promote reducing unnecessary network resources and preventing a broadcast storm where a broadcast frame is repeatedly transmitted along a loop.
The foregoing embodiments, aspects and advantages are merely exemplary and are not to be construed as limiting the invention. Also, the description of the embodiments of the invention is intended to be illustrative, and not to limit the scope of the claims, and various other alternatives, modifications, and variations will be apparent to those skilled in the art. Therefore, although a few embodiments of the invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in the embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.
Number | Date | Country | Kind |
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2005-31505 | Apr 2005 | KR | national |