Scheduling of realtime communication in switched networks

• US 7,486,681 B2
• Filed: 03/01/2004
• Issued: 02/03/2009
• Est. Priority Date: 02/28/2003
• Status: Active Grant

• Current Assignee: Siemens AG
• Original Assignee: Siemens AG
• Inventors: Weber, Karl
• Primary Examiner(s): Shah; Chirag G
• Assistant Examiner(s): Zhou; Yong
• Application Number:
  US10/788,472
• Publication Number:
  US 20040233905A1
• Time in Patent Office: 1,800 Days
• Field of Search: 370/394, 370/395.41, 370/395.42, 370/486, 370/493
• US Class Current: 370/395.4
• CPC Class Codes: H04L 12/417 with deterministic access, e.g. token passing
• CPC Class Codes: H04L 2012/4026 Bus for use in automation systems

Abstract

A method and a switching router for simple scheduling of realtime data telegrams with calculable load-insensitive cycle times. A transmission cycle (4) is subdivided into three phases. In a first phase (1), only realtime data telegrams are sent; in a second phase (2), realtime and non-realtime data telegrams are sent; and in a third phase (3), the transmission of long non-realtime data telegrams is suppressed. Short filler telegrams can be sent during the phase (3). This ensures that data transmission of the realtime data telegrams will proceed smoothly. Transmission in certain phases is regulated by the priorities assigned to the data telegrams.

Claims

1. A method of data transmission over a network, comprising:

in a first phase during a transmission cycle, sending solely realtime data telegrams over the network;

in a second phase during the transmission cycle, sending at least one of realtime data telegrams and non-realtime data telegrams over the network; and

in a third phase during the transmission cycle, sending at least one of short filler telegrams and non-realtime data telegrams while suppressing the transmission of those of the non-realtime data telegrams for which the transmission cannot be concluded during the third phase,

wherein the third phase is followed by a new transmission cycle with a new first phase, during which solely further realtime data telegrams are sent, and

wherein the non-realtime data telegrams contain user application data.

2. The method as claimed in claim 1, wherein the network comprises an Ethernet.

3. The method as claimed in claim 1, wherein said sending comprises forwarding the data telegrams.

4. The method as claimed in claim 1, implemented on a switching router, whereby the switching router has at least four transmission priorities.

5. The method as claimed in claim 1, wherein transmission of the short filler telegrams is concluded before the new first phase is started.

6. The method as claimed in claim 1, further comprising performing a time synchronization of the switching routers.

7. The method as claimed in claim 6, wherein the time synchronization is performed with a calculation of a delay between two nodes of the network in combination with a synchronization signal.

8. The method as claimed in claim 1, wherein the network is designed as a line.

9. A switching router for data transmission over a network, having at least four implemented priorities and configured to:

send exclusively realtime data telegrams over the network in a first phase of a transmission cycle in accordance with the priorities;

send at least one of realtime data telegrams and non-realtime data telegrams over the network in a second phase of the transmission cycle in accordance with the priorities; and

send at least one of short filler telegrams and non-realtime data telegrams but suppress, in accordance with the priorities, the transmission of those of the non-realtime data telegrams in a third phase of the transmission cycle for which the transmission cannot be concluded during the third phase,

wherein the non-realtime data telegrams contain user application data.

10. The method as claimed in claim 9, wherein the network comprises an Ethernet.

11. The method as claimed in claim 9, wherein the sending comprises forwarding the data telegrams.