ATM cells within frame relay technology

• US 5,987,034 A
• Filed: 08/30/1996
• Issued: 11/16/1999
• Est. Priority Date: 08/30/1996
• Status: Expired due to Term

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Land, Robert A., Swanson, David E., Simon, Robert, Rumer, Mark
• Primary Examiner(s): NGUYEN, CHAU T
• Application Number:
  US08/705,236
• Time in Patent Office: 1,173 Days
• Field of Search: 370/469, 370/395, 370/396, 370/397, 370/389, 370/465, 370/474, 370/466, 370/473
• US Class Current: 370/465
• CPC Class Codes: H04L 2012/5619 Network Node Interface, e.g. tandem connections, transit switching
• CPC Class Codes: H04L 2012/5645 Connectionless
• CPC Class Codes: H04L 2012/5652 Cell construction, e.g. including header, packetisation, depacketisation, assembly, reassembly
• CPC Class Codes: H04L 2012/567 Frame Relay over ATM
• CPC Class Codes: H04Q 11/0478 Provisions for broadband connections

Abstract

A frame relay communications network consists of a number of interconnected nodes. The network nodes include segmentation and reassembly device for fragmenting variable length frames of user data into packets of a predefined length. A preferred embodiment uses ATM AAL5 segmentation and reassembly to construct cells. Header and trailer information is added to each of the cells for transport across the frame relay network.

Claims

1. A method of transferring data across a frame relay network by fragmenting user data frames into packets having a fixed length, the method comprising the steps of:

receiving at a first node of the frame relay network a user data frame;

appending trailer information to the user data frame to form a first data unit;

segmenting the first data unit into a plurality of packets, each of the packets having a fixed length;

appending to each of the packets a frame relay header, the frame relay header comprising network routing information operable to direct the packets of data across the frame relay communications network; and

transmitting the packets from the first node to a second node of the frame relay communications network.

2. The method of claim 1 wherein the segmenting further comprises packets configured to provide variable bit rate connections.

3. The method of claim 2 wherein the frame relay header further comprises virtual circuit information, payload type information, and cell loss priority information.

4. The method of claim 3 wherein said step of appending further comprises attaching beginning-of-frame, end-of-frame and error detection information to the packet.

7. The method of claim 1 wherein the step of segmenting the user data frame comprises using an asynchronous transfer mode adaptation layer to generate packets, wherein each packet is forty-eight octets in length.

8. The method of claim 1 wherein the segmenting further comprises packets configured to provide error detection.

5. A frame relay access device comprising:

a buffer coupled to an input of the frame relay access device, wherein the buffer is operable to receive a user frame; and

a segmentation and reassembly unit, wherein the segmentation and reassembly unit is operable to append trailer information to the user frame, the segmentation and reassembly unit is further operable to segment the appended trailer information and user frame into packets having a fixed length and configured to transmit data solely across a frame relay communications network.

6. A frame relay access device as in claim 5 wherein said segmenting further comprises packets configured to provide variable bit rate connections.