1. Technical Field
Exemplary embodiments relate to a wireless local area network, and more particularly, to a wireless local area network system which supports roaming to another network while moving regardless of the type of a wireless terminal.
2. Description of Related Art
As wireless terminals are widely distributed and mobile communication networks are developed, the amount of use of mobile Internet, which connects to a website or a blog using a mobile wireless terminal, is rapidly increasing. A wireless short range network or a wireless local area network (WLAN) environment, which allows mobile Internet, requires seamless communication with a user. As such, the importance of roaming in a WLAN based on IEEE 802.11 standards is being highlighted. The IEEE 802.11 standards are marketed under the brand name Wi-Fi, which is an abbreviation of “wireless fidelity”. Wi-Fi or WLAN refers to a LAN that is wireless, and thus there is a limit in distance covered by the LAN. The communication speed decreases as the wireless terminal gets farther from an access point (AP), and if the wireless terminal completely deviates from the range, a disconnection occurs. Roaming is a function of moving connection from one AP to another AP while maintaining network connection of the wireless terminal. A plurality of APs, which provide the same service set ID (SSID) so that the SSIDs may sufficiently overlap, need to be distributed for seamless, flexible roaming. In the WLAN connection service, which uses a conventional AP and wireless terminal, even though AP cells overlap, if the wireless terminal is moved between the AP cells, the Internet is disconnected because each AP forms one sub-network in the current network address. That is, the network areas of AP1 and AP2 are different. If the wireless terminal is allocated an IP address from the AP1 and moves to the area of the AP2, the network address of the AP1 is not processed in the area of the AP2, and thus the connection to the Internet is not made.
Exemplary embodiments provide a wireless local area network system which supports roaming to another network regardless of the type of a wireless terminal.
According to an aspect of an exemplary embodiment, there is provided a wireless local area network system which successfully supports roaming between APs that belong to different networks regardless of the type of the wireless terminal by applying the NAT mode to the AP.
According to a wireless local area network system according to an exemplary embodiment, seamless roaming may be possible and the problem of lack of IP may be resolved by applying a NAT mode to an access point. Furthermore, a separate DHCP server is not necessary, and thus the investment costs for the DHCP server may be reduced. Roaming at the access point end is realized, and thus AP equipment is not necessary. Also, a change in the circuit configuration of the conventional wireless network is not necessary.
According to one or more exemplary embodiments, a wireless local area network (WLAN) system based on an access point (AP) includes: a first AP; and a second AP which has a same service set identifier (SSID) as that of the first AP, wherein the first AP and the second AP are configured to respectively perform a network address translation (NAT) and have a same virtual media access control (MAC) address.
The first AP and the second AP may be configured to generate the virtual MAC address according to a predetermined scheme.
The virtual MAC address may be generated based on an original MAC address which has been set at a time of manufacturing.
The first AP and the second AP may be connected to a first router via a first switch.
The first AP may be connected to a first router via a first switch, and the second AP may be connected to the first router via a second switch.
The first AP may be connected to a first router via a first switch, and the second AP may be connected to a second router via a second switch.
The first router may be configured to function as a dynamic host configuration protocol (DHCP) server having an internet protocol (IP) address pool of a first class or a second class.
The first AP and the second AP may be respectively configured to function as a DHCP server having the IP address pool of the first class and the second class.
The first router and the second router may be respectively configured to function as a DHCP server having the IP address pool of the first class and the second class.
The above and other features and advantages of the exemplary embodiments will become more apparent with reference to the attached drawings.
The attached drawings for illustrating exemplary embodiments are referred to in order to gain a sufficient understanding of the exemplary embodiments, the merits thereof, and the objectives accomplished by the implementation of the exemplary embodiments.
The exemplary embodiments may be modified in various different forms, and the scope of the present invention is not limited to the exemplary embodiments described below. Rather, the exemplary embodiments are provided to complete the present disclosure and completely let those of ordinary skill in the art understand the concept of the present invention.
Hereinafter, exemplary embodiments will be described in detail with reference to the attached drawings.
In the WLAN system 200 according to an exemplary embodiment, the first AP 210 and the second AP 212 may be configured to be allocated an IP address of class B or class C. The router 240 may function as a DHCP server having the IP address pool of class B or class C. The first AP 210 and the second AP 212 may be allocated the IP address of class B or class C by the router 240, wherein IP addresses allocated for the first AP 210 and the second AP 212 from B class or C class are different. The first AP 210 and the second AP 212 may have the DHCP server function having the IP address pool of class B or class C. The method of making the MAC address of the first AP 210 and the second AP 212, which is detected by the wireless terminal, the same, by introducing the virtual MAC address concept, may cause a collision between IP addresses. If the IP address pool allocated by the router 240 is class C, the IP address of the first AP 210 and the second AP 212 has an IP address of the same class C, and the number of IP addresses, which may be held by the wireless terminal connected to the first AP 210 and the second AP 212, is merely 253. That is, the IP address, which the wireless terminal has been allocated from the first AP 210, may have already been allocated to another wireless terminal by the second AP 212 and may be used. The IP address pool, which is allocated by the router 240 to prevent a collision of a private IP address allocated to the wireless terminal, may be extended from class C to class B. In this case, the first AP 210 and the second AP 212 may now be allocated the IP address of a different class B by the router 240. For example, the IP addresses, which may be held by the first AP 210, may be 172.30.1.1 to 253. The IP addresses which may be held by the second AP 212 may be 172.30.2.1 to 253. The IP address (third octet is “1”) allocated to the wireless terminal by the first AP 210 cannot be the same as the IP address (third octet is “2”) allocated to the wireless terminal by the second AP 212. Hence, even if the first AP 210 and the second AP 212 have the same MAC address, there is no possibility of a collision of the IP address at the time of roaming.
The switch 120 may be a layer-2 (L2) switch, which is located in a data link layer and is connected to a different data link. The L2 switch performs switching with the MAC address. The L2 switch processes the wireless terminal of an area narrower than that of the router 240, performs a role of transmitting a packet, and transmits the packet to the wireless terminal by using the MAC address of the wireless terminal in the MAC layer. Furthermore, the L2 switch transmits the packet to the wireless terminal by using the mapping information of the physical connection port between the MAC address of the wireless terminal and the AP, which accepts the wireless terminal. The MAC address is also called an Ethernet hardware address, an adapter address, or a physical address. The MAC address is used only when the wireless terminals communicate via the AP, and is not used when disconnecting from the Internet. When disconnecting from the Internet, the MAC is substituted by the MAC address of a sharer.
The router 240 may distinguish the network as the layer-3 router and provide the IP address to the wireless terminal according to the request of the wireless terminal. As such, the wireless terminal within the area belongs to the same network area. That is, the first AP 210 and the second AP 220 belong to the network area of the router 240. The router 240 may accept the L2 switch and transmit packets within the network. The router 240 is a representative layer 3 (L3: network layer) device, checks the destination address of the packet using the routing function and transmits the packet to the destination, and has a routing function of selecting the path to use as the optimal path at the time of transmission. The router 240 may accommodate a plurality of L2 switches.
In the WLAN according to another exemplary embodiment, the first AP 310 and the second AP 312 may be configured to be allocated the different IP addresses from classes B and C. The router 340 may function as a DHCP server having the IP address pool of class B or class C. The first AP 310 and the second AP 312 may be allocated the different IP addresses from classes B and C by the router 340. The first AP 310 and the second AP 312 may have a function of the DHCP server having the IP address pool of class B or class C. A detailed description of the exemplary embodiment of
In the WLAN system 400 according to another exemplary embodiment, the first AP 410 and the second AP 412 may be configured to be allocated the IP address of different classes B and C. The router 400 may function as a DHCP server having the IP address pool of class B or class C.
In the case of the exemplary embodiment of
The case of applying a virtual MAC address concept, and applying a technical concept of allocating the same virtual MAC address between APs and a technical concept of extending the IP address pool for preventing an IP address collision between wireless terminals at the time of roaming, with respect to the AP, has been described above. However, the exemplary embodiments are not limited thereto, and those of ordinary skill in the art may modify the exemplary embodiments and apply the modified embodiments to the network equipment having a routing function and a DHCP server function.
While the exemplary embodiments have been particularly shown, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims.
Number | Date | Country | Kind |
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10-2011-00030383 | Apr 2011 | KR | national |
This is a national stage application of PCT/KR2011/007806, filed on Oct. 19, 2011, which claims priority from Korean Patent Application No. 10-2011-0030383, filed on Apr. 1, 2011, in the Korean Intellectual Property Office, the disclosures of which are hereby incorporated herein in their entireties by reference.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/KR11/07806 | 10/19/2011 | WO | 00 | 10/1/2013 |