Apparatus and method for efficiently modifying network data frames

• US 20060146881A1
• Filed: 01/06/2005
• Published: 07/06/2006
• Est. Priority Date: 01/06/2005
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Chang, Chih-jen, Verplanken, Fabrice J., Basso, Claude, Calvignac, Jean L.
• Granted Patent: US 7,522,621 B2
• Time in Patent Office: Days
• US Class Current: 370/476
• CPC Class Codes: H04L 49/90 Buffering arrangements
• CPC Class Codes: H04L 49/901 using storage descriptor, e.g. read or write pointers
• CPC Class Codes: H04L 49/9021 Plurality of buffers per packet

Abstract

Apparatus and method for storing network frame data which is to be modified. A plurality of buffers stores the network data which is arranged in a data structure identified by a frame control block and buffer control block. A plurality of buffer control blocks associated with each buffer storing the frame data establishes a sequence of the buffers. Each buffer control block has data for identifying a subsequent buffer within the sequence. The first buffer is identified by a field of a frame control block as well as the beginning and ending address of the frame data. The frame data can be modified without rewriting the data to memory by altering the buffer control block and/or frame control block contents without having to copy or rewrite the data in order to modify it.

Claims

1. An apparatus for storing network frame data which is to be modified comprising:

a plurality of buffers for storing said network data; and

a control memory for storing;

(a) a plurality of buffer control blocks associated with each buffer establishing a sequence of said buffers, each control block having data (SBA) for identifying a subsequent buffer in said sequence; and

(b) a frame control block which identifies the address (FBA) of a buffer control block for a first buffer in said sequence, and the position (SBP) in said first buffer of the starting address of a packet of said data in said first buffer.

2. The apparatus for storing network frame data according to claim 1, wherein said control memory frame control block includes data (EBP) which identifies the ending byte position of said data in said first buffer.

3. The apparatus for storing network frame data according to claim 1, wherein said buffer control blocks include data identifying the beginning location (SBP) in said subsequent buffer containing said data, and the ending position (EBP) containing said data.

4. The apparatus for storing network frame data according to claim 1, wherein said frame control block includes the next address of a subsequently received frame.

5. The apparatus for storing network frame data according to claim 4, wherein said frame control block further includes data (BCNT) identifying the number of bytes stored in the next data frame message.

6. The apparatus for storing network frame data according to claim 3, wherein said buffer control blocks contain data (BUC) identifying the number of instances the buffer is shared with other frames of data.

7. A method for modifying a data frame comprising:

creating a frame control block identifying the first buffer containing said data frame;

creating a buffer control block for each of said buffers containing data, said buffer control block identifying the next buffer in a sequence of said buffers having said frame data;

modifying the data of one of said control blocks so that it identifies said added control block and buffer location containing data to be added to said frame data; and

adding a buffer control block identifying a buffer location containing data to be combined with said data frame, and identifying one of said buffers as the next buffer whereby said buffer control blocks form a linked list of buffers including said buffer location containing said new data.

8. A method for modifying a data frame comprising:

storing said data frame in a plurality of buffers;

creating a frame control block identifying the first buffer containing said data frame;

creating a buffer control block for each of said buffers containing data, said buffer control block identifying the next buffer in a sequence of said buffers having said frame data;

changing the data in at least two of said buffer control blocks to identify a new sequence of buffers containing a frame of data.

9. The method according to claim 8, wherein said frame data is modified to delete data stored in one of said buffers.

10. The method according to claim 8, wherein said frame data is modified to include additional data stored in an additional buffer, comprising the additional steps of:

changing the data in one of said buffer control blocks to identify said additional buffer;

creating a new control block to identify the buffer previously identified in said modified control block; and

wherein a new sequence of buffers including said additional buffer is created.

11. The method according to claim 8, further comprising changing data in said frame control block to reflect a new byte count for said frame.

12. The method for modifying data according to claim 8, further comprising:

modifying the data of a first control block which points to a buffer in said sequence where new data is to be added to point to said created buffer control block, and to indicate that data of said buffer data ends at an insertion point for said new data;

creating a second buffer control block corresponding to a buffer that contains new data to be added to said data frame which identifies the insertion point in a buffer containing the original frame data; and

creating a third buffer control block corresponding to an empty buffer which is pointed to by said second buffer control block and which points to a buffer which was previously pointed to by the first control block.

13. The method for modifying data according to claim 8, further comprising:

modifying the data of a first control block which points to a buffer in said sequence where data is to be deleted to point to a second buffer control block, and to indicate that data of said buffer ends at an point of deletion of deleted data; and

creating a second buffer control block corresponding to an empty buffer which is pointed to by said first buffer control block and which points to a buffer which was previously pointed to by the first control block.

14. A method for joining data packets in a second frame to data packets in a first frame comprising:

storing said first frame data in a first plurality buffers;

storing said second frame data in a second plurality of buffers;

creating a first frame control block which identifies the first buffer which stores said first frame data;

creating buffer control blocks which identify the next buffer in a sequence of said first frame data;

creating buffer control blocks which identify the next buffer in the sequence of said second plurality of buffers;

modifying the buffer control block for the last of said first plurality of buffers to identify the first buffer of said second plurality of buffers which hold said second frame data.

15. The method for joining data packets in a second frame to packets in a first frame according to claim 14, further comprising:

including in each of said buffer control blocks a starting address of the next buffer in a respective sequence of buffers.

16. The method according to claim 14, wherein said frame control block includes starting and ending addresses for said first buffer data.

17. A method for splitting a frame of data into two frames of data comprising:

storing said frame of data in a plurality of buffers;

creating a firs frame control block to identify a first of said buffers to hold said frame of data;

creating a second frame control block to identify the first of said buffers having data for a second frame;

creating buffer control blocks for each of said buffers, each buffer control block pointing to a subsequent buffer in a respective frame of data.