FIELD OF THE INVENTION

[0001] The present invention relates to a network linking device, and more particularly to a network linking device in communication with a computer host and an external network. The present invention also relates to a method for transferring data packets between a computer host and an external network via a network linking device.

BACKGROUND OF THE INVENTION

[0002] Please refer to FIG. 1 which is a schematic block diagram illustrating an internal structure of a personal computer in communication with an external network. The personal computer includes a microprocessor 10 , a north bridge chip 11 , a south bridge chip 12 , a memory 111 and a network interface card 121 . The memory 111 is coupled to the north bridge chip 11 . The network interface card 121 is coupled to the north bridge chip 11 via a peripheral component interconnect (PCI) bus. The network interface card 121 includes a media access controller (MAC) 1211 and a physical layer device (PHY) 1212 . In some configurations, the MAC 1211 could be directly integrated into the south bridge chip 12 . The PHY 1212 is used for connecting to an external network.

[0003] When tranceiving data packets, the MAC 1211 asserts an interrupt signal to the microprocessor 10 for interrupting hardware. The microprocessor 10 suspends the performing work to deal with an interrupt service routine (ISR) in the driver for the MAC 1211 .

[0004] Conventionally, the MAC 1211 asserts an interrupt signal according to one of the following manners:

[0005] 1. a packet-based manner, i.e. asserting a hardware interrupt signal whenever a data packet or a predetermined number of data packets to be transmitted;

[0006] 2. a time-based manner, i.e. asserting a hardware interrupt signal periodically; or

[0007] 3. a hybrid manner, i.e. combining the above packet- and time-based manners.

[0008] For the packet-based manner, the data packets can be timely picked up by the operating system, and the occupied memory resource is efficiently released. When the data packet throughput in the network is high, however, the frequently generated interrupt signals will result in that the operation resource of the microprocessor 10 is highly occupied by the network linking device so as to adversely affect the performance of the system.

[0009] On the other hand, for the time-based manner, the data packets can be processed to release the occupied memory resource without disturbing the microprocessor 10 too much. Once the data packet throughput is low, however, data packets must wait much longer to be transferred in response to the interruption, and the data packets cannot be efficiently transferred to the operating system.

[0010] For the hybrid manner, it is necessary to regulate the timing for asserting the interrupt signal to transfer data packets according to the data packet throughput. In practice, however, it is hard to control the timing for the MAC 1211 to assert the hardware interrupt signal since it is hard to predict the data packet throughput.

[0011] As described above, the assertion of the interrupt signal is either packet-based or time-based. For a situation that a data file includes a plurality of data packets and the data packets transmitted sequentially in response to the interrupt signal do not include the last packet of the data file, the microprocessor 10 , although having been interrupted, will not notify the operating system to pick up the data packets. In stead, the data packets will be buffered in the memory. The occupied memory will not be released until the complete data file including the last packet is received. Meanwhile, the microprocessor 10 resumes the proceeding thread suspended due to the interruption. In other words, the interruption of the microprocessor 10 , in spite of occupying the operation resource of the microprocessor 10 , does not result in the release the occupied memory resource under this circumstance.

[0012] With the popularization of the broadband network, the data flow through the MAC 1211 increases a lot, and thus the interrupt frequency to the microprocessor 10 increases. The above-mentioned problem that the operation resource of the microprocessor 10 is unduly occupied is even serious. Especially for a server that cooperates with a plurality of terminals in a network system, several network interface cards (NICs) are required in the server to expand its bandwidth. If the network interface cards generate the interrupt signals in a manner as above, the performance of the server will be reduced due to frequent hardware interruption, and a hang-up situation may even occur.

[0013] Therefore, the purpose of the present invention is to contemplate how to assert the interrupt signal at proper timing.

SUMMARY OF THE INVENTION

[0014] An object of the present invention is to provide a network linking device and a method for transferring data packets to assert the interrupt signal properly for avoiding deterioration of the server performance.

[0015] According to an aspect of the present invention, there is provided a network linking device in communication with a computer host and an external network. The network linking device includes a media access controller (MAC), a buffer and a feature value evaluator. The MAC in communication with the external networkreceives a data packet from the external network, and the buffer in communication with the MAC stores the data packet therein. The feature value evaluator in communication with the buffer determines whether the data packet complies with a transfer condition according to a feature value included in the data packet and actuates the MAC to assert an interrupt signal to the computer host when the feature value indicates the data packet complies with the transfer condition, thereby allowing the computer host to perform a corresponding interrupt service for the transfer of the data packet from the buffer in response to the interrupt signal.

[0016] For example, the buffer can be a static random access memory (SRAM).

[0017] Preferably, the feature value evaluator is a microprocessor.

[0018] In an embodiment, the transfer condition is complied with when the data packet is the one required to be transferred immediately upon being received by the MAC.

[0019] In another embodiment, the transfer condition is complied with when the data packet is the last one of a plurality of associated data packets to be transferred together.

[0020] Preferably, the network linking device further includes a flash memory in communication with the feature value evaluator for storing therein program codes and initial data required for the operation of the feature value evaluator.

[0021] Preferably, the feature value is one of a destination address (DA) of the data packet, a data type of the data packet, a specified content of the data packet, or a combination thereof. The specified content of the data packet is preferably one of a hardware type, a protocol type, a target Internet protocol (IP), a target hardware address (HA), a flag, a code bit or a combination thereof.

[0022] According to another aspect of the present invention, there is provided a network linking device in communication with a computer host and an external network. The network linking device includes a media access controller (MAC), a buffer and a feature value evaluator. The MAC in communication with the external network receives a data packet from the external network, and stores the packet in the buffer in communication therewith. The feature value evaluator in communication with the buffer determines whether the data packet complies with a transfer condition according to a feature value of the data packet and allows the data packet to be transferred along with an associated data packet from the buffer when the feature value indicates the data packet complies with the transfer condition.

[0023] Preferably, the data packet is determined to comply with the transfer condition when the data packet is the last packet of a data file. Meanwhile, the associated data packet is one of the data file preceding the last packet.

[0024] According to another aspect of the present invention, there is provided a method for transferring a data packet between a computer host and an external network. The method comprising steps of receiving a data packet from the external network, storing the data packet in a buffer, determining whether the data packet complies with a transfer condition according to a feature value of the data packet, and performing an interrupt service by the computer host to transfer the data packet out of the buffer when the feature value indicates the data packet complies with the transfer condition.

[0025] Generally, the data packet is transferred between the computer host and the external network via a media access controller (MAC), and the buffer is in communication with the MAC.

[0026] Preferably, the interrupt service is performed by the computer host in response to an interrupt signal asserted by the MAC upon the data packet complies with the transfer condition.