Communication control unit with lower layer protocol control and higher layer protocol control

• US 5,289,469 A
• Filed: 01/16/1992
• Issued: 02/22/1994
• Est. Priority Date: 01/17/1991
• Status: Expired due to Term

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Tanaka, Koichi
• Primary Examiner(s): Olms, Douglas W.
• Assistant Examiner(s): Nguyen, Chau T.
• Application Number:
  US07/821,045
• Time in Patent Office: 768 Days
• Field of Search: 370/94.1, 370/94.2, 370/60, 370/60.1, 370/79, 370/102, 370/110.1, 370/85.1, 370/85.2, 370/85.6, 370/85.13, 370/85.4, 370/85.5
• US Class Current: 370/469
• CPC Class Codes: G06F 13/128 for dedicated transfers to a network for protocol converters G06F13/387
• CPC Class Codes: H04L 12/40143 involving priority mechanisms hybrid switching fabrics H04L12/6402; intermediate storage or scheduling H04L49/90; time-division multiplex systems H04J3/00
• CPC Class Codes: H04L 69/321 Interlayer communication protocols or service data unit [SDU] definitions; Interfaces between layers
• CPC Class Codes: H04L 9/40 Network security protocols

Abstract

In the communication control unit lower layers communication control device includes first and second buffers. When MAC frames are received, these are input to the first buffer. By contrast, when LLC frames are received, these are first input to the second buffer, and then, transfered into a shared memory through output means. The second buffer operates as a ring buffer scheme and LLC frames can be received without missing any one after another in this unit, as long as the second buffer has enough capacity. Furthermore, only LLC frames are stored in the second buffer, thus enabling simplification of buffer management.

Claims

1. A communication control unit comprising:

first communication control means for executing lower layer protocols relating to layers no higher than a specific layer;

second communication control means for executing higher layer protocols relating to layers higher than said specific layer; and

a shared memory for transferring data between said first and second communication control means;

said first communication control means comprising

frame receiving means having a judging part in which a beginning and an end of a frame are recognized from serial data received through an input network, and a recognition part for determining whether said frame has to be transferred to said second communication control means,

first buffer means for buffering first type frames which need not be treated by said second communication means,

second buffer means for buffering second type frames which must be treated by said second communication means, said second buffer means comprising a ring buffer capable of storing a plurality of frames,

data output means for reading out frames stored in said second buffer means and for writing said frames into said shared memory, and

reporting means for reporting said frames in said shared memory to said second communication control means,

said second buffer means judging whether or not a frame to be transferred to said second communication means is stored therein and activating said data output means to transfer said frames from said second buffer means to said shared memory.

2. The communication control unit as claimed in claim 1, wherein said first buffer means stores medium access control (MAC) frames.

3. The communication control unit as claimed in claim 1, wherein said second buffer means stores logical link control (LLC) frames.

4. The communication control unit as claimed in claim 1, wherein said second buffer means includes:

means for storing frames and control information;

first means for holding a first address for said frame receiving means to write said frame and control information attached thereto into said means for storing frames and control information;

second means for holding a second address for said data output means to read out said frames from said storing means and write said control information into said means for storing frames and control information;

third means for holding a third address for said reporting means to read out said frames and said control information from said means for storing frames and control information;

means for detecting an overflow of said second buffer means from contents held in said first and third address holding means, and for informing said frame receiving means of said overflow;

means for detecting whether there is a stored frame in said second buffer means, from contents held in said first and second address holding means, and for informing said data output means of said stored frame; and

means for detecting whether there is a frame, which should be processed by said reporting means in said second buffer means, from contents held in said second and third address holding means.

5. The communication control unit as claimed in claim 4, wherein said frame receiving means stores frames in said first buffer means if MAC frames, and stores frames in said second buffer means if LLC frames unless said overflow of said second buffer means is detected.

6. The communication control unit as claimed in claim 4, wherein said ring buffer continuously stores a plurality of blocks, each comprising communication data and control data contained in one input frame as one unit, and wherein said ring buffer overwrites next control data over said communication data when read out.

7. A communication control unit comprising:

first communication control means for executing lower protocol layers relating to layers no higher than a specific layer;

second communication control means for executing higher protocol layers relating to layers higher than said specific layer; and

a shared memory for transferring data between said first and second communication control means;

said first communication control means comprising

frame receiving means having a judging part in which the beginning and the end of frames are recognized from serial data received through an input network, and a recognition part for determining whether said frames are MAC frames or LLC frames,

first buffer means for buffering said MAC frames,

second buffer means for buffering said LLC frames,

data output means for reading out said LLC frames stored in said second buffer means and for writing said LLC frames into said shared memory,

reporting means for reporting said LLC frames to said second communication control means,

a ring buffer for storing said LLC frames,

first means for holding a first address for said frame receiving means to write said input LLC frames into said ring buffer,

second means for holding a second address for said data output means to read out said input frames from said ring buffer;

third means for holding a third address for said reporting means to read out said input frames from said ring buffer as well as to write control information into said ring buffer,

first means for detecting an overflow of said ring buffer from information stored in said first and third address holding means, and for informing said frame receiving means of said overflow,

second means for detecting an LLC frame existing in said ring buffer from information stored in said first and second address holding means, and for providing a detection indication to said data output means, and

third means for detecting an LLC frame remaining in said ring buffer which should be processed by said reporting means, from information stored in said second and third address holding means.

8. A communication control unit comprising:

first communication control means for executing lower layer protocols relating to layers no higher than a specific layer;

second communication control means for executing higher layer protocols relating to layers higher than said specific layer; and

a shared memory for transferring data between said first and second communication control means;

said first communication control means comprising

frame receiving means having a judging part in which a beginning and an end of a frame are recognized from serial data received through an input network and a recognition part for determining whether or not said frame has to be transferred to said second communication control means,

reporting means for reporting said frame in said shared memory to said second communication control means,

first buffer means for buffering first type frames which need not be treated by said second communication means,

second buffer means for buffering second type frames which must be treated by said second communication means, said second buffer means comprising a ring buffer capable of storing a plurality of frames;

data output means for reading out frames stored in said second buffer means and for writing said frames into said shared memory,

said second buffer means including means for storing frames and control information,

first means for holding a first address for said frame receiving means to write frame and control information attached thereto into said means for storing frames and control information,

second means for holding a second address for said data output means to read out said frames from said holding means and to write said control information into said means for storing input frames and control information,

third means for holding a third address for said reporting means to read out said frames and said control information from said means for storing input frames and control information,

means for detecting an overflow of said second buffer means from contents stored in said first and third address holding means, and for informing said frame receiving means of said overflow,

means for detecting whether there is a stored frame in said second buffer means, from information stored in said first and second address holding means, and for informing said data output means of said stored frame, and

means for detecting whether a frame, which should be processed by said reporting means, is in said second buffer means, from information stored in said second and third address holding means.

9. The communication control unit as claimed in claim 8, wherein said receiving means stores frames into said first buffer means, if MAC frames, and stores frames into said second buffer means, if LLC frames, unless said overflow of said second buffer means is detected.

10. The communication control unit as claimed in claim 8,

wherein said ring buffer continuously stores a plurality of blocks, each comprising communication data and control data contained in one input frame as one unit, and

wherein said ring buffer can overwrite next control data over said communication data when read out.

11. In a communication control unit comprising first communication control means connected to a network for receiving frames from said network and processing frames with respect to layers no higher than a specific layer, second communication means for processing frames with respect to layers higher than said specific layer and a shared memory through which said first and second communication control means exchange frames said first communication control means comprising:

a network control unit for receiving and processing frames to enable protocol execution thereof;

a master control processor operatively connected with said network control unit for receiving and processing a frame which does not need to be transferred to said second communication control means;

a frame memory control unit for accessing said accessing said shared memory to write frames in said shared memory;

first buffer means connected with said network control unit and said master control processor in order to temporary store a frame which does not need to be transferred to said second communication control means and to transfer said frame to said master control processor; and

second buffer means connected with said network control unit and said frame memory control unit to receive frames needing to be treated with respect to a layer higher than said specific layer from said network control unit, store said frames therein and transfer said frames to said frame memory control unit, said second buffer means having detection means for detecting whether said second buffer means is storing a frame to be transmitted to said frame memory control unit,

said master control processor being connected to said second buffer means for reporting a frame which needs to be transferred to said second communication control means,

said second buffer means activating said frame memory control unit, when said second buffer means is storing a frame, to transfer said frame from said second buffer means to said shared memory through said frame memory control unit.