Data transmission apparatus and method for transmitting data between physical layer side device and network layer device

A data transmission apparatus for transmitting data packets formed by encapsulating a first type of frames in a second type of frames as payload with appropriate overheads, from a physical layer side device to a network layer side device, each of said first type of frames including a SAPI field, and an information field, said apparatus comprising:

• a second receiving means for receiving the data packets from the physical layer side device;
• a second de-framing means for removing the overheads, and extracting the first type of frames from the payload of the second type of frames;
• a first de-framing means for extracting the address field and the data contained in the information field from the first type of frames;
• determining means for comparing the value of the SAPI field with a set of preset values including at least a first value and a second value, and if the value of the SAPI field data matches the first value, determining the extracted data is of a first type, and if the value of the SAPI field matches the second value, determining the extracted data is of a second type;
• and
• a second transmitting means for transmitting the extracted data packets and the determining result to the network layer side device.

A data transmission method for transmitting data packets from a network layer side device and a physical layer side device, comprising the steps of:

• receiving the data packets of a certain type from the network layer side device;
• recognizing the type of the data packets and generating a SAPI identifier according to the recognized type;
• first framing step, for encapsulating a SAPI field including said SAPI identifier and an information field including said data packets into a frame, to form a first type of frames;
• second framing step, for encapsulating said first type of frames into a payload portion, inserting appropriate overheads, to form a second type of frames;
• and
• outputting said second type of frames to the physical layer side device.

A data transmission method for transmitting data packets formed by encapsulating a first type of frames in a second type of frames as payload with appropriate overheads, from a physical layer side device to a network layer side device, each of said first type of frames including a SAPI field, and an information field, said method comprising the steps of:

• receiving the data packets from the physical layer side device;
• second de-framing step, for removing the overheads, and extracting the first type of frames from the payload of the second type of frames;
• first de-framing step, for extracting the SAPI field and the data contained in the information field from the first type of frames;
• comparing the value of the SAPI field with a set of preset values including at least a first value and a second value, and if the value of the SAPI field data matches the first value, determining the extracted data is of a first type, and if the value of the SAPI field matches the second value, determining the extracted data is of a second type;
• and
• transmitting the extracted data packets and the determining result to the network layer side device.