Patent Publication Number: US-2005124359-A1

Title: Multi-port interface for a switched wireless network

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      This invention relates generally to wireless networks, and, more particularly, to a multi-port interface for a switched wireless network.  
      2. Description of the Related Art  
      A Wireless Local Area Network (WLAN) is a flexible data communications system that can either replace or extend a wired LAN to provide added functionality. A traditional, wired local area network (LAN) sends packets of data from one piece of equipment to another across cables or wires. A wireless local area network (WLAN) relies instead upon radio waves to transfer data. Data is superimposed onto a radio wave through a process called modulation, and this carrier wave then acts as the transmission medium, taking the place of a wire.  
      The importance of WLAN technology, however, goes beyond just the absence of wires. The advent of WLAN technology opens up a whole new definition of what a network infrastructure can be. No longer does an infrastructure need to be solid and fixed, difficult to move, and expensive to change. Instead, it can move with the user and change as fast as the organization does. For example, business people can stay connected as they move throughout the corporate campus, tapping into the resources of the wired network.  
      Wireless Local Area Network technology has been targeted by analysts as one of the fastest growing sectors in the computing industry. WLANs are used in various vertical and horizontal applications (e.g., retail, manufacturing, logistics, healthcare, education, public space, etc.). Several wireless network standards have become popular, including the 802.11x standards that have been ratified by the Institute of Electrical and Electronics Engineering (IEEE). Exemplary IEEE 802.11x standards include 802.11, 802.11a, 802.11b (also known as Wi-Fi), and 802.11g.  
      A WLAN may be configured in several ways, including using a centralized wireless switch to support communications with one or more access ports. Through the use of a wireless switch, the network access, security, policy management, and Quality of Service (QoS) features can be unified at the switch level. Deploying a wireless switch in a WLAN can also lower the overall cost of the network infrastructure because of the switch&#39;s scalability and flexibility to support existing and future wireless technologies.  
      However, despite these advantages of switched WLAN systems, there is at least one drawback in that there is no efficient way in these systems to allow a network administrator to monitor the performance of these wireless networks or to detect anomalies in the wireless traffic. One way to monitor the wireless networks is to install wireless sensors throughout the coverage area and sniff the data traffic from the air. However, the traffic captured this way is commonly in encrypted form, and thus is not readily decipherable. Another way is to monitor the wired traffic going into or coming out of a wireless switch. However, this mechanism of monitoring data does not provide the desired wireless information about the traffic.  
      Some wired network systems may include a mirror port implemented within, for example, a network switch. Through the mirror port, an administrator may observe data that flows to and from one of the several different ports of the network switch. Typically, at any given time, the mirror port allows the administrator to monitor only one port out of the several ports. To monitor a different port, the administrator first stops monitoring the current port before switching to the next, thus making it inconvenient for the administrator to monitor a plurality of ports at any given time.  
     SUMMARY OF THE INVENTION  
      In one embodiment of the present invention, a method is provided. The method comprises receiving, using a wireless controller, data transmitted from one or more wireless transmitters adapted to communicate with a plurality of mobile terminals, receiving descriptive information associated with at least a portion of the received data from the one or more wireless transmitters and providing the received data and the associated descriptive information to a port interface associated with the wireless controller.  
      In another embodiment of the present invention, a wireless switch is provided having a multi-port interface for use in a switched wireless network. The wireless switch comprises an interface and a controller communicatively coupled to the interface. The controller is adapted to receive data transmitted from a plurality of access ports, wherein the data has an associated descriptive information and provide at least a portion of the received data and the associated descriptive information to a port interface associated with the wireless switch.  
      In yet another embodiment of the present invention, a system is provided. The system comprises a plurality of mobile terminals and a wireless switch. The wireless switch is adapted to receive data transmitted from the plurality of mobile terminals, wherein the data has associated descriptive information and provide at least a portion of the received data and the associated descriptive information to a port interface associated with the wireless switch. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The invention may be understood by reference to the following description taken in conjunction with the accompanying drawings, in which like reference numerals identify like elements, and in which:  
       FIG. 1  is a block diagram of a communications system including a wireless cell controller, an interface associated with the wireless cell controller, and a plurality of access ports, in accordance with one embodiment of the present invention; and  
       FIG. 2  is a block diagram of the wireless cell controller and the associated interface, in accordance with one embodiment of the present invention. 
    
    
      While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.  
     DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS  
      Illustrative embodiments of the invention are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developers&#39; specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.  
      The words and phrases used herein should be understood and interpreted to have a meaning consistent with the understanding of those words and phrases by those skilled in the relevant art. No special definition of a term or phrase, i.e., a definition that is different from the ordinary and customary meaning as understood by those skilled in the art, is intended to be implied by consistent usage of the term or phrase herein. To the extent that a term or phrase is intended to have a special meaning, i,e., a meaning other than that understood by skilled artisans, such a special definition will be expressly set forth in the specification in a definitional manner that directly and unequivocally provides the special definition for the term or phrase.  
      Referring now to  FIG. 1 , a switched wireless communications system  100  is illustrated, in accordance with one embodiment of the present invention. The communications system  100  includes one or more components that allow mobile terminals  105  to communicate with each other or with other devices over a data network  108 . The mobile terminals  105  may communicate with other devices using any suitable communications protocol including, but not limited to, the protocols defined by the IEEE 802.11x standards, such as the 802.11a standard, 802.11b standard, and 802.11g standard.  
      For ease of illustration, three mobile terminals  105  are depicted, although it should be appreciated that in alternative embodiments, the system  100  may include more or fewer mobile terminals  105 . The mobile terminals  105  may take the form of a variety of devices, including, but not limited to, laptop computers, cellular phones, personal digital assistants (PDAs), digital pagers, and wireless cards.  
      The data network may be a private network or a public network, such as the Internet. As utilized herein, a “network” may refer to one or more communication networks, channels, links, or paths, and systems or devices (such as routers) used to route data over such networks, channels, links, or paths.  
      The communications system  100  includes one or more wireless access ports  110  communicatively coupled to a wireless cell controller (WCC)  120  through a network infrastructure  130 . The wireless cell controller  120  in the illustrated embodiment is a wireless switch, an example of which may be model WS5000 Wireless Switch provided by Symbol Technologies, Incorporation (“Symbol Technologies” hereinafter). The WCC  120  may communicate with the devices coupled to the network  108  using any of a variety of network protocols, including the IEEE 802.3 protocol. Example of access ports  110  may be the AP100 or AP200 models provided by Symbol Technologies. In other embodiments, any suitable type of wireless transceivers may be employed in place of (or in conjunction with) the access ports  110 , including access points, for example.  
      In the illustrated embodiment of  FIG. 1 , the network infrastructure  130  may be in the form of a network hub or a switch, such as an Ethernet hub or switch. The network infrastructure  130  may include one or more network routers (not shown), in one embodiment.  
      Although the invention is not so limited, in the illustrated embodiment the WCC  120  and/or the access ports  110  may provide one or more Medium Access Control (MAC) layer functions, including, but not limited to, association management, Quality of Service, roaming, ad hoc mode, authorization, buffer management, and installation/configuration, cyclic redundancy check, channel access, timeout/retransmission, packet acknowledgments, header processing, rate control, beacon processing, and interface to the physical layer. Fragmentation/reassembly and encryption functions may also be performed.  
      The general flow of data packets within the communications system  100  is described next. In the upstream direction (i.e., from the access port  110  to the WCC  120 ), the access port  110  receives (encrypted) data packets from the mobile terminals  105  and forwards the received data packets to the WCC  120 . In one embodiment, the access port  110  also provides descriptive information associated with the data packets to the WCC  120 , where the descriptive information may include information such as a time stamp, relative signal strength index, signal quality, and channel information. The access port  110  may, in one embodiment, encapsulate the descriptive information along with the data from the mobile terminals  105  before transmitting the encapsulated data to the WCC  120 . In an alternative embodiment, the WCC  120 , instead of the access port  110 , may perform the encapsulation feature. The type of descriptive information provided by the access port  110  may vary from one implementation to another, and thus in some embodiments, additional, different, or less descriptive information may be encapsulated with the data packet.  
      Upon receiving the transmitted data information, along with any associated descriptive information, the WCC  120  buffers, parses, decrypts the received data and delivers it to its intended destination (which may be a mobile terminal  105  or a device communicatively coupled to the network  108 ). In the reverse direction, the data received by the WCC  120  for transmission to the mobile terminals  105  is buffered, formatted, and encapsulated within a packet and provided via the network infrastructure  130  to the access port  110 , which extracts the mobile unit packet from the encapsulated packet and forwards the extracted packet to the appropriate mobile terminal  105 .  
      The WCC  120  of  FIG. 1  includes a port interface  140  associated therewith. The communications system of  FIG. 1  further includes a processor-based system  150 , which in the illustrated embodiment is a server  150 . As discussed in greater detail below, in accordance with one or more embodiments of the present invention, the port interface  140  of the WCC  120  can be utilized to provide one or more features that can be useful in analyzing the performance of the communications system  100 . These features may include, but are not limited to, detecting wireless intrusion (i.e., detecting anomalies in the wireless traffic), monitoring performance of the wireless communications system  100 , and/or sniffing capability. In one embodiment, these feature(s) may be performed by the WCC  120  with which the port interface  140  is associated. In an alternative embodiment, one or more of these features may be performed at the direction of the server  150 . In such an embodiment, the port interface  140  may support a command interface to allow the server  150  to communicate with the WCC  120  to perform some of the aforementioned features, such as the wireless intrusion detection. In the event a wireless intrusion is detected, the server  150  can, via the command interface, instruct the WCC  120  to change the current channel of communications.  
      It should be understood that the configuration of the communications system  100  of  FIG. 1  is exemplary in nature, and that fewer, additional, or different components may be employed in other embodiments of the communications system  100 . For example, while in the illustrated embodiment, the wireless cell controller  120  communicates with the access port  110  through the network infrastructure  130 , in an alternative embodiment, these components may interface with each other without an intervening network infrastructure  130 . As another example, in one implementation, the port interface  140  may be integrated within the wireless cell controller  120 . Alternatively some or all portions of the port interface  140  may be implemented in a standalone device that is adapted to communicate with the wireless cell controller  120 . The manner in which the port interface  140  is associated with the wireless cell controller  120  is a matter of design choice, and thus may vary from one implementation to another. Similarly, other variations may be made to the illustrated configuration of the communications system  100  without deviating from the spirit and scope of the invention.  
      Referring now to  FIG. 2 , a block diagram of the wireless cell controller  120  and the associated port interface  140  of  FIG. 1  is illustrated, in accordance with one embodiment of the present invention. In the illustrated embodiment of  FIG. 2 , the port interface  140  is integrated within the WCC  120 .  
      The WCC  120  includes a control unit  205  and a storage unit  208  that is communicatively coupled to the control unit  205 . An example of the control unit  205  may be a processor. The illustrated embodiment of the WCC  120  further includes a module  210  for transmitting and receiving data to and from the access ports  110  through a network interface  220 . The data received from the access ports  110  may include data packets transmitted by the mobile terminals  105 , as well as the descriptive information (discussed above) associated with these data packets. In the illustrated embodiment, the network interface  220  of the WCC  120  is communicatively coupled to the network infrastructure  130  (shown in  FIG. 1 ). In an alternative embodiment, a plurality of ports (not shown) may be utilized to connect the WCC  120  to the access ports  110  without an intervening network infrastructure  130 .  
      The WCC  120  further includes an encryption/decryption module  225 . The module  225  decrypts data that is received from the access ports  110 , and encrypts data that is transmitted to the access ports  110 . This extends the wireless security domain, protecting communications from the access ports  110  to the WCC  120 . Those skilled in the art having the benefit of this disclosure will appreciate that the particular encryption and decryption algorithms employed in a given communications system can vary from one implementation to another.  
      In the illustrated embodiment, the server  150  (see  FIG. 1 ) may access the WCC  120  via the port interface  140  to perform a variety of desired features, including, but not limited to, monitoring performance of the wireless communications system  100 , multi-port sniffing of transmitted and received data, and/or detecting wireless intrusion. The server  150 , can be an open platform enabling a plurality of software functions by vendors other than the switch manufacturer. Each of these features is described below.  
      With respect to the monitoring capability, the port interface  140  allows an administrator situated at the server  150  to view and analyze the data packets (e.g., 802.11 packets in the illustrated example) that are transmitted to and from the WCC  120  by the mobile terminals  105  via the access ports  110 . Implementing the port interface  140  in association with (or as part of) the WCC  120  can be advantageous because substantially all of the data transmitted by the access ports  110  passes through the WCC  120 , and thus can be readily monitored via the port interface  140 . In accordance with one embodiment of the present invention, because the WCC  120  is a centralized switch through which a plurality of access ports  110  transmits data, it is possible to monitor data transmitted by these pluralities of access ports  110  at any given time. Alternatively, if desired, data from less than all of the access ports  110  under the control of the WCC  120  can be monitored.  
      In one embodiment of the present invention, the port interface  140  may also allow the administrator to view and analyze the descriptive information associated with the data packets. As noted earlier, the descriptive information may include time stamp, relative signal strength index, signal quality, access port identifier, and/or channel information associated with the transmission of the data packets from the access ports  110 . The descriptive information may be encapsulated, for example, with the 802.11 data packets before the encapsulated information is provided to the server  150  through the port interface  140 . Having access to the encapsulated information can be useful to an administrator desiring to evaluate the performance of the wireless communications system  100  or to trouble shoot communications problems. This is because the descriptive information associated with the data packets (e.g., 802.11 packets, for example) provides the administrator with a wide array of information (e.g., data stamp, access port identifier, transmission channel characteristics) to identify problematic areas in the communications system  100 . In one embodiment, if desired, the port interface  140  may be utilized to “dump” or save the encapsulated data to a storage unit (not shown) of the server  150  or to a storage unit of another device.  
      Although not so limited, in one embodiment, the following encapsulated format may be employed: the element ID |length|data|. The element ID field may include information such as the timestamp, RSSI, Channel Number, 802.11 packet, and the like. The length field may include the length of the data that is stored in the data field.  
      As noted above, in one embodiment, the port interface  140  may also support data sniffing capabilities. Through the port interface  140 , the server  150  can gain access to data that is, for example, transmitted to the WCC  120  from the mobile terminals  105 . Because the port interface  140  is implemented in association with (or as part of) the WCC  120 , the server  150  can utilize this port interface  140  to access decrypted data. In contrast, conventional mirror ports that are typically implemented in wired network hubs (at the network infrastructure level), do not have access to decrypted data because the decryption is performed by the WCC  120 .  
      In one embodiment, the port interface  140  may also include a command instruction module  250  that allows two-way communications between the server  150  and the WCC  120 . Through the module  250 , the server  150  may perform one or more desired tasks. For example; the server  150  may instruct the WCC  120  to communicate with another access port  110  in response to determining a denial of service attack on the present communications channel. As another example, the server  150 , acting as a remote wireless intrusion detection device, may inform the WCC  120  to disassociate a malice mobile terminal  105 , or drop harmful packets.  
      Furthermore, the server  150 , in one embodiment, can perform complex spectral analysis and descriptive information received from the access ports  110  via the WCC  120 . This enables the server  150  to reconfigure the WCC  120  and respective access ports  110 , so as to optimally reallocate frequency channel assignments (dynamic channel assignment) or change antenna patterns to improve wireless system performance.  
      In one embodiment the server  150 , negotiates with the WCC  120 , via the port interface  140 , a set of services supported by the WCC  120  and associated access ports  110 . This enables various classes of servers, hosting varying degrees of functions, to be interconnected, and for the WCC  120 , to dynamically configure itself to provide the necessary set of data and descriptive information to the server  150 . The communications from the WCC  120 , and the server  150 , may be encapsulated in a publicly published standard described using XML and may describe discovery and UDDI (Universal Description, Discovery, and Integration).  
      It should be appreciated that only selected components of the WCC  120  of  FIG. 2  are shown that are helpful in understanding the various embodiments of the invention, and that in alternative embodiments, the WCC  120  may include fewer, additional, or different components without deviating from the spirit and scope of the invention.  
      In summary, in accordance with one embodiment of the present invention, the WCC  120  includes an associated port interface  140  that provides one or more useful features. For example, in one embodiment, the port interface  140  may be utilized to monitor the data that is received from and/or transmitted to the WCC  120 , where the data may be monitored in substantially real-time. In another embodiment, the port interface  140  may support data dump (i.e., allow a user to store the monitored data to a storage device, which may be located within the WCC  120  or in an external device). In yet another embodiment, the port interface  140  may be responsive to commands received from the server  150  to allow an administrator to direct the WCC  120  to execute desired task(s). For example, the server  150  may instruct the WCC  120  to change the current communications channel that is being utilized to a different one for improved service.  
      Unless specifically stated otherwise, or as is apparent from the discussion, terms such as “processing” or “computing” or “calculating” or “determining” or “displaying” or the like, refer to the action and processes of a computer system, or similar electronic computing device, that manipulates and transforms data represented as physical, electronic quantities within the computer system&#39;s registers and memories into other data similarly represented as physical quantities Within the computer system&#39;s memories or registers or other such information storage, transmission or display devices.  
      Those skilled in the art will appreciate that the various system layers, routines, or modules illustrated in the various embodiments herein may be executable control units (such as the control unit  205  (see  FIG. 2 )). The control unit  205  may include a microprocessor, a microcontroller, a digital signal processor, a processor card (including one or more microprocessors or controllers), or other control or computing devices. The storage devices  208  referred to in this discussion may include one or more machine-readable storage media for storing data and instructions. The storage media may include different forms of memory including semiconductor memory devices such as dynamic or static random access memories (DRAMs or SRAMs), erasable and programmable read-only memories (EPROMs), electrically erasable and programmable read-only memories (EEPROMs) and flash memories; magnetic disks such as fixed, floppy, removable disks; other magnetic media including tape; and optical media such as compact disks (CDs) or digital video disks (DVDs). Instructions that make up the various software layers, routines, or modules in the various systems may be stored in respective storage devices. The instructions when executed by a respective control unit  205  causes the corresponding system to perform programmed acts.  
      The particular embodiments disclosed above are illustrative only, as the invention may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the invention. Accordingly, the protection sought herein is as set forth in the claims below.