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A Method for Ensuring Successful Data Delivery in an Asynchronous Data Transfer

IP.com Disclosure Number: IPCOM000010894D
Original Publication Date: 2003-Jan-30
Included in the Prior Art Database: 2003-Jan-30
Document File: 2 page(s) / 44K

Publishing Venue

IBM

Abstract

In an environment that transfers data from a source to a destination using packets, it may become necessary for the source to know that a particular packet has arrived at the destination. This is especially true if real-time control of a remote piece of hardware is required (when the contents of the next transfer to the destination is based on the destination's response to the previous packet contents). This invention, called a "Wrap Byte", provides a means for the source to determine if a particular packet has arrived at the destination.

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  A Method for Ensuring Successful Data Delivery in an Asynchronous Data Transfer

    Each data packet transmitted by the source contains a Packet Tag, called the "Wrap Byte" in addition to any other packet identification data. An example of this Write Data packet structure is shown in Figure 1.

Data ID

Byte Count B

Wrap Byte Data Byte 1 Data Byte 2

.

.

.

Last Data Byte Checksum

Packet Type Identifier

Packet Tag

Transfer Data

End of Data

Byte Count A

Packet Header

Transfer Byte Count

Packet Data

and Checksum

When the destination logic receives this packet, the "Wrap Byte" is copied from the packet header and temporarily stored while the data in the packet is stored and processed. When storing and processing has finished, the destination logic then transfers the "Wrap Byte" to the destination's "Wrap Byte" register for use in subsequent receive packets (data transferred from the destination back to the source). An example of this Read Data packet structure is shown in Figure 2.

Data ID

Byte Count B Reserved Data Byte 1 Data Byte 2

.

.

.

Last Data Byte

Checksum

Figure 1 - Write Data Packet Structure.

Packet Type Identifier

Byte Count A

Packet Header

Transfer Byte Count

Wrap Byte Packet Tag

The "Wrap Byte" is sent following the last data byte. The source logic can interrogate the "Wrap Byte" contents and determine if the desired data packet has yet arrived and been processed. The position of

Transfer Data

End of Data

Figure 2 - Read Data Packet Structure.

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