Optimizing fragment sizes in frame relay networks

• US 20040202191A1
• Filed: 06/08/2001
• Published: 10/14/2004
• Est. Priority Date: 06/08/2001
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Vrabel, Robert Andrew
• Granted Patent: US 6,990,079 B2
• Time in Patent Office: Days
• US Class Current: 370/412
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/16 in connection oriented networks, e.g. frame relay
• CPC Class Codes: H04L 47/2416 Real-time traffic
• CPC Class Codes: H04L 47/245 using preemption
• CPC Class Codes: H04L 47/36 by determining packet size, e.g. maximum transfer unit [MTU]
• CPC Class Codes: H04L 47/43 Assembling or disassembling of packets, e.g. segmentation and reassembly [SAR]

Abstract

Fragmentation of non-realtime data for transmission in frame relay networks is sized dynamically according to available bandwidth. The bandwidth is determined according to burst interval and burst size calculations based on parameters including the amount and type of realtime data to be sent and the percentage of burst interval utilized by the realtime data. If no realtime data is being sent, then the fragment sizes of the non-realtime data are adjusted to utilize the entire available bandwidth.

Claims

1. A method in a frame relay transmission to make efficient use of bandwidth comprising:

maintaining separate queues to store realtime data and non-realtime data to be transmitted;

providing a fragment queue to hold fragments of data to be transmitted;

checking in order to determine whether the realtime data queue and then the non-realtime data queue is empty;

transmitting realtime data in successive packets when the realtime data queue is not empty;

fragmenting non-realtime data dynamically according to available transmission bandwidth; and

transferring fragmented non-realtime data to the fragment queue for transmission after transmission of realtime data.

2. The method of claim 1 wherein the fragmenting step includes

determining fragment sizes according to available burst intervals.

3. The method of claim 2 including

setting values for a maximum number of expected voice calls, for access rates of link devices within the system, for voice sampling and compression rates, and for acceptable voice traffic delays;

ascertaining a burst interval based on the acceptable voice traffic delays value;

calculating a value of a committed burst size based on the burst interval divided by the access rates of link devices; and

computing a fragment size according to the committed burst size less overhead and size of voice fragments.

4. A data transmission system for optimal utilization of bandwidth comprising:

a frame relay data link layer for coupling data to be transmitted to the data transmission system;

a queuing mechanism for controlling a plurality of data queues;

a circuit level priority queuing mechanism for interfacing the queuing mechanism to the frame relay data link layer; and

a frame relay traffic shaping device for preparing data fragments to be transmitted.

5. The system of claim 4 wherein said queuing mechanism includes:

a realtime data queue;

a non-realtime data queue; and

a fragment queue.

6. The system of claim 5 further including:

testing means arranged to test whether the realtime data queue contains data to be transmitted;

coupling means to transmit contents of said realtime data queue in response to a nonempty signal from the scanning means; and

transfer means connected relative to the non-realtime data queue and the fragment queue for moving fragments of data from the non-realtime data queue to the fragment queue.

7. The system of claim 6 wherein said transfer means includes:

means responsive to the frame relay traffic shaping device for determining the size of data fragments to be moved from the non-realtime data queue to the fragment queue.

8. The system of claim 7 wherein said frame relay traffic shaping device includes:

calculating means responsive to system parameters for supplying size information to the transfer means by dynamically determining an optimum fragment size.

9. The system of claim 8 wherein the calculating means includes:

data supplying means providing parameters including a maximum volume of expected realtime data and data access rates of devices within said system;

computation means responsive to the data supplying means for calculating a fragment size to utilize all available bandwidth in the system; and

output means for supplying the fragment size to the transfer means.