3com Corporation

Pauline Cheng

Burton B Lo

Anthony Liem Pan

A method for efficient data transfers between domains of differing data formats. In one exemplary implementation, data transfer is performed with respect to an IEEE 1394 communication domain and an Ethernet communication domain. The novel data transfer method advantageously eliminates the need to copy the data payload section of a received data packet from one memory region to another memory region within a bridge device coupled between first and second communication domains. Specifically, the header, data payload and trailer sections of a received data packet (of a first communication domain format) are copied into a first portion of memory within the bridge device. The present invention then assembles a new data packet by constructing a new header of a second communication domain and appending a pointer to the new header that points to the data payload location within the first portion of memory. The header includes a destination address obtained from the data payload location and a source address of the bridge device. The new packet is of the second communication domain. The bridge device then transmits the new header section to the second communication domain and forwards the data payload therewith using the pointer as a reference. Domain interface controller circuits then add the new trailer, as required, to the new packet. By passing a pointer to the data payload, the present invention eliminates the need to copy the data payload from one region of memory to another during the transfer operation.

Method for efficient data transfers between domains of differing data formats

A method for managing data transfers with minimal host processor involvement. Data is transferred between a peripheral device coupled to a host computer and a network device over a high performance bus. In one exemplary embodiment, data is transferred over a bus utilizing the IEEE 1394 communication protocol and a network utilizing the Ethernet communication protocol. The novel data transfer method advantageously minimizes the involvement of the host computer's processor in the management of data transfers, thus maximizing the host processor's availability for performing other computations. Specifically, to transfer data from the peripheral device to the network, the host processor generates a data pointer table and sends it to the network device. A processor in the network device then takes over data transfer management, using information in the data pointer table to locate and transmit the designated block of data from the peripheral device to the network. In another embodiment, the present invention determines whether the size of a data block to be transferred exceeds the maximum packet size for the relevant communication protocol used by the bus or the network. If such a limit exists and is exceeded, the data pending transfer is divided into multiple packets, such that each packet conforms to the maximum packet size of the limiting protocol. Then, the smaller packets are transmitted iteratively until the entire data block is transferred. As such, the present invention eliminates the incompatibility problem posed by the differences in packet sizes among different communication protocols.

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Pleasanton, CA, United States of America

Pauline Cheng