Abstract:
A system and method for providing network communications between personal computer systems using USB communications. The disclosed USB networking hub allows multiple hosts to exist in a USB-based network. The networking hub includes an integrated virtual network adapter, which provides for communications among and between multiple hosts.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to computer system networks, and more particularly to networked personal computer systems. Still more particularly, this application relates to the use of Universal Serial Bus based communications for computer networking. 
     2. Description of the Prior Art 
     Computer networking is, and has been for some years, common in, the industry. The ability to connect many computer systems in a network, whether as server/client or peer-to-peer, has become an indispensable tool to business, and has recently begun to enter users&#39; homes. To make computer networking available to as many people as possible, it is desirable to make these networks as easy to set up and operate as possible. 
     Current networking equipment generally consists of a network interface card (NIC), which is installed in each computer system, then connected to other computer systems. Even the installation of the NIC is beyond the abilities of most computer users, since it generally entails actually opening the computer system chassis and physically installing the NIC on the system board. 
     Each NIC must then be connected either to a network hub, which allows many systems to be networked in a “hub and spoke” arrangement, or directly to one or more other systems in a daisy-chain arrangement. Each system must then be configured to communicate with each other system, using appropriate operating-system drivers. Other equipment, such as a printer, may then be attached to the network, and shared between the computer systems on that network. 
     Because of the relative complexity of setting up a computer network, it is beyond the ability of most individuals or small businesses, unless they are willing and able to take on the cost of hiring a technician to do the installation. It would therefore be desirable to achieve a means of networking computer systems and equipment that is as easy as possible. 
     The Universal Serial Bus (USB) specification describes a cable bus that supports data exchange between a host computer and a wide range of simultaneously accessible peripherals. The bus allows peripherals to be attached, configured, used, and detached while the host and other peripherals are in operation; i.e., the peripherals are “hot swappable.” Because most personal computer systems now include an installed USB port, users are able to simply plug in any number of peripherals to the host computer system, allowing a wide range of devices to be easily attached and detached. 
     The host computer system is the system where the-USB Host Controller is installed. This includes the host hardware platform (CPU, bus, etc.) and the operating system in use; this is generally the only actual computer system present, with all other attached USB devices being either USB hubs or peripheral devices for that computer system. It is important to note that the USB specification, available at http://www.usb.org and hereby incorporated by reference, requires that only one host be present in any USB system. 
     A USB system has three primary types of devices, the USB host, described above; one or more USB devices, such as printers, scanners, and modems; and the USB interconnect, which is the manner in which USB devices are connected to and communicate with the host. The interconnect includes the Bus Topology, the Inter-layer Relationships, Data Flow Models, and the USB Schedule. The details of the interconnect, and device and host requirements, may be found in the USB specification, and is not of concern to the average user. 
     Because of the ease of using USB connections and devices for the average user, it is a preferred means of implementing many communications between computer systems and devices. Since the USB specification requires that there is only one USB host in any system, however, USB has not been available for use in networking multiple computer systems. Therefore, it would be desirable to provide a means for combining the ease-of-use of a USB system into a computer networking system, to provide an improved computer networking system that is technically accessible to most users. 
     SUMMARY OF THE INVENTION 
     It is therefore one object of the present invention to provide an improved computer system network. 
     It is another object of the present invention to provide an improved system and method for personal computer networking. 
     It is yet another object of the present invention to provide an improved system and method for personal computer networking utilizing Universal Serial Bus based communications. 
     There is therefore provided a system and method for providing network communications between personal computer systems using USB communications. The disclosed USB networking hub allows multiple hosts to exist in a USB-based network. The networking hub includes an integrated virtual network adapter, which provides for communications among and between multiple hosts. 
     The above as well as additional objectives, features and advantages of the present invention will become apparent in the following detailed written description. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself, however as well as a preferred mode of use, further objectives, and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein: 
     FIG. 1 is a block diagram of a data processing system in accordance with the preferred embodiment of the present invention; 
     FIG. 2A depicts a block diagram of a networking hub in accordance with the preferred embodiment of the present invention; 
     FIG. 2B depicts a block diagram of a networking hub in accordance with an alternate embodiment of the present invention; 
     FIG. 3 is a more detailed block diagram of a virtual network adapter in accordance with a preferred embodiment of the present invention; 
     FIG. 4 depicts a flowchart of the initialization process of the virtual network adapter in accordance with a preferred embodiment of the present invention; and 
     FIG. 5 is a flowchart of a data transmission routine in accordance with a preferred embodiment of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The following description details the operation and features of several preferred embodiments of the present invention, but it will be understood by those of skill in the art that the scope of the invention is defined only by the issued claims, and not by any description herein. 
     With reference now to the figures, and in particular with reference to FIG. 1, a block diagram of a data processing system in which a preferred embodiment of the present invention maybe implemented is depicted. Data processing system  100  may be, for example, one of the desktop models of personal computers available from International Business Machines Corporation of Armonk, N.Y. Data processing system  100  includes processors  101  and  102 , which in the exemplary embodiment are each connected to level two (L2) caches  103  and  104 , respectively, which are connected in turn to a system bus  106 . 
     Also connected to system bus  106  is system memory  108  and Primary Host Bridge (PHB)  122 . PHB  122  couples I/O bus  112  to system bus  106 , relaying and/or transforming data transactions from one,bus to the other. In the exemplary embodiment, data processing system  100  includes graphics adapter  118  connected to I/O bus  112 , receiving user interface information for display  120 . Peripheral devices such as nonvolatile storage  114 , which may be a hard disk drive, and keyboard/pointing device  116 , which may include a conventional mouse, a trackball, or the like, are connected via an Industry Standard Architecture (ISA) bridge  121  to I/O bus  112 . PHB  122  is also connected to PCI slots  124  and USB controller  126  via I/O bus  112 . 
     The exemplary embodiment shown in FIG. 1 is provided solely for the purposes of explaining the invention and those skilled in the art will recognize that numerous variations are possible, both in form and function. For instance, data processing system  100  might also include a compact disk read-only memory (CD-ROM) or digital video disk (DVD) drive, a sound card and audio speakers, and numerous other optional components. All such variations are believed to be within the spirit and scope of the present invention. Data processing system  100  and the exemplary networking hubs described below are provided solely as examples for the purposes of explanation and are not intended to imply architectural limitations. 
     Referring now to FIG. 2A, the networking hub  200  includes multiple sub-hubs,  202 , 204 , 206 , each of which has an associated virtual network adapter (VNA)  210 , 212 , 214 , respectively. Each sub-hub is connected to a single upstream host at host connections  220 , 222 , 224 , and is connected to one or more USB devices on ports  230 , 232 , 234 . It is noted that the USB specification refers to USB peripheral devices as “functions,” and the terms “device” and “function” will be used interchangeably here. Each sub-hub allows communications, in a conventional manner, between its respective upstream host and devices attached to its ports. Although, in this exemplary diagram, only one port is shown attached to each sub-hub, those of skill in,the art will realize that each sub-hub can support multiple ports. 
     The respective VNAs  210 , 212 , 214  of each sub-hub are interconnected over logical interconnect  240  to provide for communications among and between each sub-hub. By communicating over the VNA system, communications are provided between the multiple hosts. Each sub-hub can accommodate a single upstream connection, a single VNA, and one or more downstream connections. It should be noted that upstream connections  220 , 222 , 224 , need not be directly to a host, but may be connected, for example, over a series of interconnected USB hubs. 
     The VNA system is provided to overcome one limitation of the USB specification, which requires that only one host can connect to each USB system. The VNA  210 , 212 , 214  appears to each host, in the preferred embodiment, as an ethernet adapter attached to its respective sub-hub  202 , 204 , 206 . Each host therefore is able to communicate with each other sub-hub, and with the nodes and devices attached to the other sub-hubs, by communicating over the VNAs of the respective sub-hubs. 
     With reference now to FIG. 2B, an alternate networking hub  250  is provided, in which a single VNA controller  260  manages communications between each sub-hub  252 , 254 , 256 . This embodiment, which appears to the hosts and USB devices to be functionally identical to the embodiment of FIG. 2A, reduces needless duplication of logic by combining the functions of multiple VNA controllers  210 , 212 , 214  into a single VNA controller  260 . The single VNA appears to each sub-hub as its own dedicated network device. 
     This system operates as above, allowing hosts on upstream attachments  270 , 272 , 274  communicate via sub-hubs  252 , 254 , 256 , respectively, to USB devices on ports  280 , 282 , 284 . VNA  250  allows communications between the sub-hubs, so that each host can effectively communicate with other hosts. Inter-VNA module  286  and inter-hub VNA connection  288  allow multiple networking hubs to be interconnected. 
     Referring now to FIG. 3, a more detailed block diagram of an exemplary VNA  300  is shown. VNA  300  is a single VNA with multiple sub-hub inputs, as shown in FIG.  2 A. USB I/F blocks  330 , 340 , 350  are USB interface connections for the USB sub-hubs which the VNA interconnects. These are connected to microcontroller  310 , which manages VNA communications. The VNA firmware  370  is preferably stored in a non-volatile FLASH memory. Random access memory  360  is used asa buffer and scratchpad memory. 
     The inter-VNA port  380  is an optional port used to connect directly to another VNA. In the preferred embodiment, communications over this port are standard serial communications, and a standard null-modem cable can be used to connect multiple VNAs. Of course, if a higher bandwidth is desired, this port can be implemented with any number of high-speed interconnects. 
     The USB I/F (VNA) block  320  is an optional dedicated USB port for the VNA to act as a USB “function” or device. This may be used for a USB host to communicate directly with the VNA, for example to update the VNA firmware. 
     In reference to FIG. 4, a flowchart detailing the initialization sequence of the network hub is shown. Upon startup (step  410 ), the VNA microcontroller initializes and enables the USB interfaces to be recognized and attached by any attached sub-hubs (step  420 ). The connected sub-hubs then recognize the VNA and attach it as a USB function (step  430 ). After this, when the host queries the sub-hub over its USB upstream connection (step  440 ), the sub-hub indicates the VNA as an attached USB function (step  450 ). The host then attaches the VNA as a USB/Network function (step  460 ), since it sees the VNA as a network adapter attached to the USB sub-hub. The host then loads an appropriate network driver for the VNA (step  470 ), and the initialization routine ends (step  480 ). 
     With reference now to FIG. 5, a flowchart showing the VNA data transport routine is shown. When the system is operating (step  510 ), the VNA microcontroller will receive a data packet from a host via the sub-hub over one of its USB interfaces (step  520 ). This data packet is buffered in the VNA RAM (step  530 ), then sent out to the destination sub-hub (step  540 ). It should be noted that when the data packet is resent out, the VNA controller will rebroadcast this packet only to the non-originating USB interfaces; this prevents the originating sub-hub from receiving the resent packet broadcast. Next, if the inter-VNA port is enabled (step  550 ), the data packet is also sent out over the inter-VNA connection (step  560 ). Finally, when all broadcasts have completed, the VNA RAM,buffer is cleared (step  570 ) and the routine ends (step  580 ). 
     While the invention has been particularly shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention. For example, while the above description discusses is specifically drawn to the Universal Serial Bus specification, the disclosed networking system and virtual network adapter can be modified to any number of communications standards and different computer architectures and systems. Other variations are certainly within the ability of one skilled in the art, and are expected to fall within the scope of the claims.