|Publication number||USRE41397 E1|
|Application number||US 10/704,464|
|Publication date||Jun 22, 2010|
|Filing date||Oct 22, 2003|
|Priority date||Jun 30, 1997|
|Also published as||US6393483|
|Publication number||10704464, 704464, US RE41397 E1, US RE41397E1, US-E1-RE41397, USRE41397 E1, USRE41397E1|
|Inventors||Faisal Latif, Pramod Sharma, Suleman Saya, Jim J. Kuhfeld|
|Original Assignee||Adaptec, Inc.|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (54), Non-Patent Citations (4), Referenced by (6), Classifications (18), Legal Events (8)|
|External Links: USPTO, USPTO Assignment, Espacenet|
1. Field of the Invention
This invention relates generally to computer networks, and more particularly to software drivers used for controlling network interface cards.
2. Description of the Related Art
Computers are increasingly being coupled together into computer networks. In typical networks, hardware devices known as network interface cards (NICs) are used by computer systems to enable them to communicate over networks with other computer systems. Commonly, NICs are available as plug in devices that are connected to a computer's interface bus (e.g., PCI Bus), or are built directly into a computer's mother board. Traditionally, a computer's NIC enables communication over a single computer network, such as a Local Area Network (LAN), which may include a multitude of switches and network devices. Through these network devices, remote hosts are capable of communicating with other similarly connected remote hosts or to a server computer system. Through these networks, remote hosts are able to, for example, request data from a server computer system, and the server computer system is able to transfer the requested data to the requesting host over the network. In response to the increased demand for resources stored on networked server computers, many NICs are now capable of communicating over more than one network. In this manner, data stored on one server computer system may be accessed by hosts coupled to different networks (e.g., different LANs).
Because NIC 30 is responsible for providing the communication path between a multitude of remote hosts, the loading experienced by NICs installed on a server computer system 20 are far greater than the typical loads experienced by NICs installed on the individual remote hosts. By way of example, server computer system 20 typically receives a few short requests from the remote hosts and then responds by transmitting out a great deal of data to the requesting hosts. In addition, because NIC 30 is only able to transmit out to each network at a fixed bandwidth (e.g., about 10 Mbps/100 Mbps), the server computer system 20 will unfortunately be tied up responding to data transmit request for extended periods of time.
Another common problem with conventional NICs is that access to server computer system 20 may be completely blocked-off to an entire network whenever one port fails to operate properly. By way of example, if port P1 fails, all hosts connected to LAN-1 10 will be prevented from accessing data stored on server computer system 20. As is well known, port failures are common, and are typically caused by network overloads, NIC software driver bugs, NIC link interface failures, and NIC hardware failures. In any event, when a failure occurs, a large number of users attempting to access or transfer data between the server computer system 20 will be unable to accomplish their networking task. Typically, when a NIC port (e.g., port P1) failure occurs, the server computer system 20 is typically shut down to all network traffic (i.e., LANs 10, 12, 14, and 16) while network technicians trouble shoot and fix the NIC port failure. Of course, network repairs may disable a network for several hours or even days.
As businesses continue to intensely network their operations, port failures will unfortunately lead to substantial losses in worker productivity. For example, many companies use a central server to network their employees that may be located in several remote office locations. As such, when the port servicing a particular office goes down, that entire office will be unable access shared data stored in the central server. NIC port failures are also common in large corporations such as, banks, hotel chains, and airlines that critically depend on real-time access to data stored on a central server computer. Consequently, NIC port failures are commonly to blame for significant yearly losses in revenue as well as lower customer satisfaction.
In view of the foregoing, there is a need for a network interface card(s) (NICs) that provide increased load balancing transmit throughput to networks connected to the NIC, while providing resilient backup capabilities that enable continues data transferring connections when port failures occur. Further, there is a need for NIC software drivers to intelligently detect port failures and automatically redistribute data transfer loads over functioning NIC ports.
Broadly speaking, the present invention fills these needs by providing methods and apparatus for increasing throughput in a load balancing manner over a multi-port NIC. Each port of the multi-port NIC preferably has its own link to the network, hub, or switch, which enables the multi-port NIC to reconfigure automatically to recover from a port failure. The multi-port NIC, driven by a smart NIC driver preferably reconfigures the multi-port driver by redistributing the load (both transmit and receive) over the remaining active ports. It should be appreciated that the present invention can be implemented in numerous ways, including as a process, an apparatus, a system, a device, a method, or a computer readable medium. Several inventive embodiments of the present invention are described below.
In one embodiment, a process for driving a network interface card is disclosed. The process includes monitoring the status of a plurality of ports connected between a computer and a network. Detecting a failure in one of the plurality of ports connected to the network. Re-assigning data transmitted over the failed one of the plurality of ports to an active port of the plurality of ports selected in a round robin technique. The process further including receiving data over one of the plurality of ports designated as a primary receiving port. In a preferred embodiment, when the failed one of the plurality of ports is the primary receiving port, the receiving tasks are assigned to a next active port selected in a round robin technique.
In another embodiment, a method for transmitting and receiving data over a network from a server computer system is disclosed. The method includes connecting a plurality of ports between the server computer system and the network for communicating with a plurality of remote hosts coupled to the network. Transmitting a load of data through the plurality of ports to the plurality of remote hosts. Detecting a failure in one of the plurality of ports during a transmit to a selected one of the plurality of remote hosts. The method further includes redistributing the load of data assigned to the failed one of the plurality of ports to an available port of the plurality of ports. Preferably, data is received through one of the plurality of ports designated as a primary receiving port.
In yet a further embodiment, a computer readable media containing program instructions for driving a network interface card is disclosed. The computer readable media includes program instructions for monitoring a status of a plurality of ports connected between a computer and a network. Program instructions for building a port resolution table indexing connections to at least one remote host that is communicating through a selected one of the plurality of ports. The computer readable media further includes program instructions for periodically updating the port resolution table after a predetermined time-out. Preferably, the at least one remote host is assigned host parameters identifying a media access control address of the at least one remote host, a number assigned to the selected one of the plurality of ports, and a timer.
In still another embodiment, a computer readable media containing program instructions for driving a network interface card is disclosed. The computer readable media includes program instructions for monitoring a status of a plurality of ports connected between a computer and a network. Program instructions for detecting a failure in one of the plurality of ports connected to the network. Program instructions for re-assigning data transmitted over the failed one of the plurality of ports to an active port of the plurality of ports selected in a round robin technique. The computer readable media further includes program instructions for receiving data over one of the plurality of ports designated as a primary receiving port.
In another embodiment, an apparatus for driving a network interface card is disclosed. That apparatus includes means for monitoring a status of a plurality of ports connected between a computer and a network. Means for detecting a failure in one of the plurality of ports connected to the network. Means for re-assigning data transmitted over the failed one of the plurality of ports to an active port of the plurality of ports selected in a round robin technique. The apparatus further includes means for receiving data over one of the plurality of ports designated as a primary receiving port.
Advantageously, the embodiments of the present invention provide a multi-port network interface card having a plurality of ports connected to a single network, and a smart network interface driver for controlling the functions of the multi-port card and interactions with existing server operating systems. As such, it should be appreciated that no changes are required to be made to existing operating systems or other applications to take advantage of the increased throughput and redundancy provided in accordance with the present invention. Further, all internal load balancing and aggregation provides a resilient network interface card that automatically reconfigures itself in case of failure to one or more of the ports, and the re-configuration occurs in real-time without requiring operator intervention. These and other aspects and advantages of the invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.
The present invention will be readily understood by the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals designate like structural elements, and in which:
An invention is described for methods and apparatus for increasing throughput in a load balancing manner over a multi-port NIC. The present invention also provides a smart NIC driver for managing loads over the multi-port NIC and redistributing loads over active ports when failures occur with a given port of the multi-port NIC. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be obvious, however, to one skilled in the art, that the present invention may be practiced without some or all of these specific details. In other instances, well known process operations have not been described in detail in order not to unnecessarily obscure the present invention.
In one embodiment, the multi-port NIC is well suited for server computer systems that are required to transfer large amounts of data over a network in response to numerous short data requests. Preferably, the multi-port NIC of the present invention has each of its ports linked to the network, hub, or switch, and each port acts as an independent NIC having an associated bandwidth. Accordingly, the multi-port NIC of the present invention is capable of simultaneously transmitting data over each of the ports to a particular remote host located within a network with an aggregated bandwidth. By way of example, if each port of the multi-port NIC has a bandwidth of 100 Mbps, and the multi-port NIC is a 4-port card, the total aggregated bandwidth can be 400 Mbps, or higher for NICs with additional ports. Further, when ever a port of the multi-port NIC fails, the smart NIC driver that controls the operability of the multi-port NIC will automatically redistribute the load over the remaining ports that remain active.
Preferably, the present invention uses a “single” instance of the smart NIC driver 126 to control each port of the multi-port NIC 130. In this manner, the operating system 124 is capable of interfacing with the smart NIC driver 126 to control the multiple ports of a multi-port NIC 130 in a manner that is transparent to the operating system 124. That is, although smart NIC driver 126 is controlling multiple ports to a single network, its interface with existing operating systems will be essentially identical to software drivers used to conventionally control data flow through a single port. Therefore, the smart NIC driver 126 is seamlessly able to communicate with any of the well established network protocols controlled by operating system 124, including TCP/IP, Netware and NetBEUI.
In the example of
To manage packet switching, switch 140 typically creates routing tables and stores packet data in queues before routing the data to its destination, which may be any one or more Hosts 132a through 132n, that may be connected to switch 140 of network 110. Although only one switch has been illustrated for ease of description, it should be understood that typical networks include a multitude of network devices interconnecting a plurality of hosts through many hubs, switches, repeaters, bridges and routers.
It is important to note that each one of the ports P1, P2, P3, and P4 may transmit data through switch 140 at the same time in a load balanced manner which advantageously enables multi-port NIC 130 to increase its transmit throughput. For example, assume that ports P1, P2 and P4 are currently transmitting packets through switch 140 of network 110, and when a new transmit request is received for a new host (currently not in the PRT table) by multi-port NIC 130, the smart NIC driver 126 of
As mentioned above, port P1 is preferably designated as the primary receive (Rx) port assigned all receiving tasks of packet data coming from Hosts 132a through 132n shown connected to network 110. Because NICs resident in server computers are typically requested to transmit out substantially more data than it is required to receive, only one port is actually necessary for efficiently performing the receive functions of multi-port NIC 130. However, if port P1 fails for any reason, smart NIC driver 126 will automatically re-assign the receive (Rx) tasks to the next active port (in a round robin orientation) of multi-port NIC 130. Once assigned to the next active port, the port that is now assigned with the receiving task will also be assigned the Ethernet MAC address of port P1. In this manner, all upper layer protocols will continue sending data to the same destination address “DA” associated with the Ethernet MAC address of P1.
It is important to point out that because the primary Rx's Ethernet MAC address is assigned the port taking over the receiving functions, all external hosts connected to the network 110 will be unable to tell a difference in the internal and transparent re-assignment of server 120 receiving functions. As such, the internal re-assignment of the primary Rx Ethernet MAC address is transparently controlled by the smart NIC driver 126, and all that external hosts understand is that the multi-port NIC 130 is continuing to function smoothly and uninterrupted.
In one embodiment, if the primary Rx Ethernet MAC address is re-assigned to another port, the port newly assigned with the receiving Rx functions will also transmit (Tx) using the source address “SA” of the primary. By way of example, assuming that the primary Rx port P1 were to fail, and the next active port was port P2, then when port P3 transmits a packet over the network, that transmitted packet will have the source address SA-1 associated with P1. As will be described in greater detail with reference to
In a like manner, if any one of the transmit ports, e.g., port P3 fails at any point during a transmission, the load assigned to port P3 will be redistributed in a round robin manner to the next active and free port of multi-port NIC 130. However, if all ports that remain active are currently busy (i.e., not free), then the load of port P3 will be assigned to the least busiest of the remaining ports, thereby enabling efficient load balancing over the remaining active ports.
Once multi-port NIC 130 has been installed into a computer and connected to a network, the method proceeds to an operation 504 where a multi-port NIC 130 configuration panel is called up in the form of a graphical user interface (GUI). The method then proceeds to an operation 506 where port configuration is performed for each port in the multi-port NIC 130 to ascertain the bandwidth (e.g., 10 Mbps, 100 Mbps, etc.) of each port. By way of example, as shown in
By default, the connection type for the available network ports is set to “auto detect default connection” which is configured to ascertain the type of connection associated with each of the particular ports. However, if the user desires to manually change the connection types, the connection types window 522 may be modified through the drop-down list box to make an appropriate change. Once the changes are made, the apply icon button is preferably selected to implement the newly entered connection types.
Referring back to
By way of example, when a port is selected from the available port list 534 and the ADD button 542a is clicked, the selected port will be shifted to a group ports list 536. Of course, ports may also be removed from the group ports list 536 by clicking remove button 542b after a port is selected from the group ports list 536. Once the selected ports are moved in or out of the group ports list 536, the user may name that group in a groups window 540, where a link check time-out is provided. As will be described in greater detail below, the link check time-out (LCT) is used to check the activity of the selected ports during operation. In the example shown, the LCT time is set to 10 seconds, however, the LCT timer may be set to any number of seconds between about 1 second and about 20 seconds.
If the user selects the status icon 548 within the port aggregation GUI 530, a port aggregation window 540 of
Next, the method proceeds to an operation 604 where the smart NIC driver 126 creates registry groups from the registry values associated with the groups configured through the graphical user interfaces. Once the smart NIC driver 126 creates the groups as shown in
The method then proceeds to an operation 704 where the destination Ethernet media access control (MAC) address is retrieved from packets that are to be transmitted over the network. By way of example, if a data packet is requested to be transmitted to a remote Host A, then the destination address “DA” of the Host A will be retrieved from the packet that is to be transmitted. The method then proceeds to a decision operation 706 where it is determined whether the retrieved Ethernet MAC address is currently listed in a PRT table.
By way of example,
If the examination of the 6th byte of the destination address “DA” of the packet to be transmitted returns, for example, a number 3, then the entire destination address “DA” of the packet being transmitted is compared to the MAC destination address of any hosts linked to the entry indexed in the PRT table. In this example, only one Host C 132c is linked to index number 3, and therefore the comparison of the DA of the packet being sent and the MAC destination address of Host C 132c should match up. However, as will be described below, if there are multiple hosts doubly linked to the same index number (i.e., both hosts have the same 6th byte) then the comparison is done for those multiple hosts that are doubly linked. Although destination and source addresses are typically 6 bytes long, comparison are preferably performed based on 8 bytes (two words) at one time to improve processing efficiency. That is, additional zero values are added to the 6 bytes of the SA and DA to ensure that comparisons are based on two words. It should be appreciated that this lookup table comparison technique is well suited to reduce the amount of processing required by the CPU of the computer containing the multi-port NIC 130, thereby reducing the number of possible CPU interrupts.
Assuming that the first packet to be transferred through multi-port NIC 130 (i.e., when none of the ports are currently in use) is a packet destined for Host C 132c as described above, then the first available port P1 will be selected in a round robin selection technique. As pictorially shown in
Continuing with the example of
As will be described with reference to
Alternatively, if it is determined in operation 708 that the port for the Ethernet MAC address is not active, the method will proceed to an operation 710 where a new port is selected for transmission to a desired remote host. Once a new port is selected from the remaining active ports (or least busiest) in a round robin technique, the method will proceed to an operation 712 where the packet(s) are transmitted over the port to the desired Ethernet MAC address of the recipient host.
On the other hand, if it is determined that the next port is not free in operation 804, the method will proceed to an operation 806 where it is determined whether all ports have been checked and been determined to have been busy. If all ports have been not been checked and been determined to have been busy, the method will proceed back to operation 802 where the method proceeds to select the next active port in a round robin orientation. Once the next active port is selected, the method will again proceed to decision operation 804 where it is determined if this next port is free. If it is again determined to not have been free, then the method will again proceed to decision operation 806 where it is again determined whether all ports have been checked and are busy.
Once all ports have been checked and have been ascertained to be busy, the method will proceed from operation 806 to operation 810, where the least busiest port is selected for transmission. Once the least busiest port has been selected for transmission, the method returns to operation 712 of FIG. 7A. In a like manner, if one port was ascertained to be free in operation 808, that port would be selected and the method would proceed to operation 712 of FIG. 7A. In sum, the selection of a new port is performed in a load balancing manner that first determines whether there are any free ports that may be used for transmission, and if there are no free ports, the method will proceed to select the least busiest port for transmission.
In operation 902, the method will then proceed to the next entry in the PRT table. The next entry is entry number 2, which again does not satisfy the condition of operation 904, therefore, the method will again proceed to operation 902 where the method moves to entry number 3. Once at entry number 3, it is determined in decision operation 904 that there is a host associated with the current PRT table entry. At this point, the method proceeds to a decision operation 906 where it is determined whether the time of the parameters box 750 is currently set to “0.” In this example, the timer is currently shown set to “1,” and therefore the method proceeds to operation 910 where the PRT timer is re-set to “0” as shown in parameters box 750a.
On the other hand, if it is determined in operation 906 that the timer was already set to “0,” then the method would proceed to operation 908, where the host entry would be deleted from the PRT table as shown in FIG. 7C. The removal of Host C 132c from the PRT table essentially means that port P1 was idle for at least a predetermined PRT timer delay time-out. In one embodiment, the PRT timer delay (TIMEOUT) is calibrated for performance optimization to a time of between about ¼ second and 1 second, and most preferably about ½ second. Of source, these preferred optimizations may vary depending on network loading as well as other factors.
Once Host C 132c entry is removed from the PRT table as shown in
Once the timer is set to “0,” the method will proceed to decision operation 912 where it is determined if there is a pointer to a next doubly linked host. Because Host B 132b is doubly linked to Host A 132a, the method will proceed back to operation 906 where it is determined if the timer of the parameters box 754 is set to “0.” Because the timer is currently set to “1,” the method will proceed to operation 910 where the timer is set to “0.” On the other hand, if the timer had been set to 0 as shown in parameters box 754a, the method would have proceeded to operation 908 where the host would be deleted from the PRT table as shown in FIG. 7C. This process will therefore continue until all 255 entries have been analyzed and the method will proceed to operation 916, where the routine will wait for a PRT timer delay (TIMEOUT). Once the TIMEOUT is complete, the method will again proceed through the PRT timer routine and commence marching through each of the entries beginning with 0, and checking the timers of each host that is currently linked (or doubly-linked) with an entry of the PRT table.
As mentioned above, if the timer of any host was previously set to 0 in a prior PRT timer routine, that host will be deleted as an entry to the PRT table as described with reference to operation 908 of FIG. 9. As such, when a host is deleted from the PRT table, the port number allocated to that host will likewise become available when a new packet transfer operation is requested to a new remote host not currently linked to the table, or the same port link may again be re-established.
Therefore, if it is determined that the primary Rx port is active, the method will proceed to a decision operation 1010 where it is determined if the primary Rx port is functioning as the receiver. By way of example, if the primary Rx port had previously failed for any reason, the receiving tasks would have been assigned to the next available active port. However, assuming that the primary Rx port is the receiver, the method will proceed to an operation 1016 where the LCT timer is re-started.
On the other hand, if it is determined that the primary Rx port is not currently the receiver in operation 1010, the method would proceed to an operation 1014 where the primary Rx port would be designated as the receiver, because it was determined in operation 1004 that the primary Rx port was active. Then, once the primary port Rx is designated as the receiver, the method would proceed to operation 1016 where the LCT timer would be restarted. Referring back to operation 1004, if it is determined that the primary Rx port is not active, then the method would proceed to a decision operation 1006.
In decision operation 1006, it is determined whether the primary Rx port is currently designated as the receiver. By way of example, assuming that the primary Rx port was functioning as the receiver, and then failed to operate properly (i.e., not active) in operation 1004, then the receiving tasks would have to be assigned to another port. Therefore, if the primary Rx port is currently the receiver and it is no longer active, the method would proceed to an operation 1012, where the next active port (selected in a round robin orientation) would be designated as the receiver. On the other hand, if it was determined in operation 1006 that the primary Rx port was not the receiver, the method would proceed to a decision operation 1008 where it is determined if the port designated as the receiver is active.
By way of example, assuming that the primary Rx port was not functioning as the receiver, and the port assigned all receiving functions also became inactive as determined in operation 1008, the method would proceed to operation 1012 where the next active port would be designated as a receiver. On the other hand, if the port designated as the receiver in operation 1008 was active, the method would proceed to operation 1016 where the LCT timer would be re-started as described above. Once the LCT timer is restarted in operation 1016, the method will proceed to an operation 1018 where a link check timer delay (TIMEOUT) would commence. In one embodiment, the LCT time-out is preferably set by the user to be between about 1 second and about 10 seconds, and most preferably, about 2 seconds. Of course, these LCT time-out parameters may be modified outside the preferred times to fit well within networks of varying load requirements. After the TIMEOUT of operation 1018, the method will proceed through the link check timer routine again as described above.
Tables A through D below illustrate the re-assignment of receiver functions to the active ports when the port assigned the receiving functions fails to operate due to software errors, hardware errors, network over-loading errors, or a combination thereof. In table A below, all ports are currently active, and the primary Rx port P1 is assigned all receiving functions. As such, each port will have its own MAC address, and transmits will be performed with their own source addresses attached to the packet.
Port P1 (Active) (Primary Rx)
Port P2 (Active)
Port P3 (Active)
Port P4 (Active)
When port P1 fails for any reason, the smart NIC driver 126 will look to the next active port, and assign the receiving functions to that port. As illustrated in Table B below, port P2 is now the receiver. As mentioned above, because port P2 is now the receiver, it will be assigned the MAC address of port P1, and when port P2 transmits out, it will transmit packets with the source address SA-1 of port P1.
Port P1 (Down) (Primary Rx)
Port P2 (Down)
Port P3 (Active)
Port P4 (Active)
If after an LCT timer routine it is determined that port P2 is no longer active (operation 1008), then the smart NIC driver 126 will designate the next active port as the receiver. As shown in Table C below, the next active port is port P3. Because port P3 is now the receiver, it will be assigned the MAC address of the primary Rx port P1, and any transmits performed from port P3 will have the source address SA-1.
Port P1 (Down) (Primary Rx)
Port P2 (Down)
Port P3 (Active)
Port P4 (Active)
When the link check timer routine is performed again after the predetermined timeout, the smart NIC driver 126 will proceed to decision operation 1004 where it will be determined that the primary Rx port P1 is again active as shown in Table D below. As such, the primary Rx port will be once again designated as the receiver as described in operation 1014, after it is determined that the primary Rx port was not the receiver in operation 1010, and shown in Table C above.
Port P1 (Active) (Primary Rx)
Port P2 (Down)
Port P3 (Active)
Port P4 (Active)
The present invention may be implemented using any type of integrated circuit logic or software driven computer-implemented operations. By way of example, a hardware description language (HDL) based design and synthesis program may be used to design the silicon-level circuitry necessary to appropriately perform the data and control operations in accordance with one embodiment of the present invention. By way of example, a VHDL® hardware description language available from IEEE of New York, N.Y. may be used to design an appropriate silicon-level layout. Although any suitable design tool may be used, another layout tool may include a hardware description language “Verilog®” tool available from Cadence Design Systems, Inc. of Santa Clara, Calif.
The invention may also employ various computer-implemented operations involving data stored in computer systems. These operations are those requiring physical manipulation of physical quantities. Usually, though not necessarily, these quantities take the form of electrical or magnetic signals capable of being stored, transferred, combined, compared, and otherwise manipulated. Further, the manipulations performed are often referred to in terms, such as producing, identifying, determining, or comparing.
Any of the operations described herein that form part of the invention are useful machine operations. The invention also relates to a device or an apparatus for performing these operations. The apparatus may be specially constructed for the required purposes, or it may be a general purpose computer selectively activated or configured by a computer program stored in the computer. In particular, various general purpose machines may be used with computer programs written in accordance with the teachings herein, or it may be more convenient to construct a more specialized apparatus to perform the required operations. An exemplary structure for the invention is described below.
The microprocessor 1116 is a general purpose digital processor which controls the operation of the computer system 1100. The microprocessor 1116 can be a single-chip processor or can be implemented with multiple components. Using instructions retrieved from memory, the microprocessor 1116 controls the reception and manipulation of input data and the output and display of data on output devices. According to the invention, a particular function of microprocessor 1116 is to assist in the port aggregation and load balancing tasks controlled by smart NIC driver 126 of multi-port NIC 130.
The memory bus 1118 is used by the microprocessor 1116 to access the RAM 1120 and the ROM 1122. The RAM 1120 is used by the microprocessor 1116 as a general storage area and as scratch-pad memory, and can also be used to store input data and processed data. The ROM 1122 can be used to store instructions or program code followed by the microprocessor 1116 as well as other data.
The peripheral bus 1124 is used to access the input, output, and storage devices used by the digital computer 1102. In the described embodiment, these devices include the display screen 1104, the printer device 1106, the floppy disk drive 1108, the hard disk drive 1110, and the network interface 1112. The keyboard controller 1126 is used to receive input from keyboard 1114 and send decoded symbols for each pressed key to microprocessor 116 over bus 1128.
The display screen 1104 is an output device that displays images of data provided by the microprocessor 1116 via the peripheral bus 1124 or provided by other components in the computer system 1100. The printer device 1106 when operating as a printer provides an image on a sheet of paper or a similar surface. Other output devices such as a plotter, typesetter, etc. can be used in place of, or in addition to, the printer device 1106.
The floppy disk driver 1108 and the hard disk drive 1110 can be used to store various types of data. The floppy disk drive 1108 facilitates transporting such data to other computer systems, and hard disk drive 1110 permits fast access to large amounts of stored data.
The microprocessor 1116 together with an operating system operate to execute computer code and produce and use data. The computer code and data may reside on the RAM 1120, the ROM 1122, or the hard disk drive 1110. The computer code and data could also reside on a removable program medium and loaded or installed onto the computer system 1100 when needed. Removable program mediums include, for example, CD-ROM, PC-CARD, floppy disk and magnetic tape.
The network interface 1112 is used to send and receive data over a network connected to other computer systems. An interface card or similar device and appropriate software implemented by the microprocessor 1116 can be used to connect the computer system 1100 to an existing network and transfer data according to standard protocols.
The keyboard 1114 is used by a user to input commands and other instructions to the computer system 1100. Other types of user input devices can also be used in conjunction with the present invention. For example, pointing devices such as a computer mouse, a track ball, a stylus, or a tablet can be used to manipulate a pointer on a screen of a general-purpose computer.
The invention can also be embodied as computer readable code on a computer readable medium. The computer readable medium is any data storage device that can store data which can be thereafter be read by a computer system. Examples of the computer readable medium include read-only memory, random-access memory, CD-ROMs, magnetic tape, optical data storage devices. The examples listed in the prior sentence are examples of computer readable storage media. The computer readable medium can also be distributed over a network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion.
Although the foregoing invention has been described in some detail for purposes of clarity of understanding, it will be apparent that certain changes and modifications may be practiced within the scope of the appended claims. In addition, it should be understood that the various processing functions described above may be implemented both in silicon as hardware integrated circuits, or as software code that may be stored and retrieved from any suitable storage medium. Accordingly, the present embodiments are to be considered as illustrative and not restrictive, and the invention is not to be limited to the details given herein, but may be modified within the scope and equivalents of the appended claims.
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|U.S. Classification||709/226, 710/200, 370/419, 709/250, 370/230, 709/239, 370/359, 370/463, 714/4.1|
|International Classification||H04L12/24, G06F15/16|
|Cooperative Classification||H04L41/22, H04L43/0817, H04L41/0668|
|European Classification||H04L41/22, H04L41/06C2, H04L43/08D, H04L12/24D3|
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