US 6,154,796 A · Apparatus and method in a network interface device for storing receiving frame status in a holding register

Abstract

A network interface device includes a random access memory used as a transmit and receive buffer for transmission and reception of data frames between a host computer bus and a packet switched network. The network interface device includes read and write controllers for each of the transmit and receive buffers, where each write controller operates in a clock domain separate from the corresponding read controller. The read and write controllers output status information corresponding to the reading or writing of a stored data frame in the receive buffer. The memory management unit includes a synchronization circuit, which arbitrates updates to the holding registers by the read and write controllers based on the asynchronously determined presence of at least one stored data frame.

Claims17

Dependent claims

A method for storing status information associated with a data frame, the method comprising:

writing the frame and corresponding status information in a random access buffer memory and supplying the written status information to a holding register according to a first clock;
reading the frame and the corresponding status information from the buffer memory and supplying the read status information to the holding register according to a second clock independent from the first clock;
asynchronously determining a presence of at least one complete stored frame in the buffer memory;
and
selectively storing one of the written status information and the read status information based on the determining step.

2 more elements

A network interface device for storing status information associated with a data frame, comprising:

a random access buffer memory;
a write controller configured for writing the data frame into the random access buffer memory according to a first clock and outputting status information of said frame;
a read controller configured for reading the stored data frame from the random access buffer memory according to a second clock independent from the first clock and outputting status information corresponding to the stored data frame;
and
a synchronization circuit asynchronously determining a presence of at least one stored data frame in the random access buffer memory, the synchronization circuit comprising a holding register and a selection circuit, the selection circuit configured for selectively storing into the holding register one of the status information output from the read controller and the status information output from the write controller.

2 more elements

Dependencies are inferred from the claim text.

Apparatus and method in a network interface device for storing receiving frame status in a holding register

Life of this patent

Apparatus and method in a network interface device for storing receiving frame status in a holding register

Life of this patent

Abstract

Claims17