Flow control of frame based data over a synchronous digital network
View Patent ↗A transmission apparatus and a method for operating the apparatus comprises means for controlling flow of frame based data transmitted from a local frame based data channel interface over a synchronous digital network. The method of operation comprises the transmitter receiving frame based data at a first rate whereafter a buffer is configured to receive the frame based data. A data amount threshold level for the buffer is pre-determined whereafter, with respect to the threshold level, an amount of transmitted frame based data that has been received is monitored. In response to monitoring the amount of data received, a signal, in the form of a pause frame, is generated wherein the signal is configurable to adapt the rate of transmission from the frame based data channel interface. Working in conjunction with the transmission means there is also provided a receiver for controlling flow of frame based data, received from a synchronous digital network, to a frame based data channel interface. The receiver is configured to receive the frame based data at a first rate whereafter a buffer is configured to receive the frame based data. Upon pre-determining a data amount threshold level for the buffer an amount of frame based data received is monitored with respect to the threshold level. In response to monitoring the amount of data received, a signal is generated in the form of a pause frame, wherein the pause frame signal is configurable to adapt the first transmission rate of the frame based data over the synchronous digital network to a second rate. In this way, the rate of transmission from a local Ethernet switch may be controlled and the rate of receipt of Ethernet based frame data from a synchronous digital network may be controlled. In the latter case pause frames may be incorporated into one or more synchronous digital hierarchy virtual containers.
1. A method of using a synchronous digital multiplexer unit for controlling flow of frame based data transmitted from a local frame based data channel interface over a synchronous digital network, comprising steps of:
receiving said frame based data at a first rate;
configuring a buffer to receive said frame based data;
predetermining a data amount threshold level for said buffer;
with respect to said threshold level, monitoring an amount of said transmitted frame based data that has been received; and
in response to said step of monitoring said amount of said data received, generating a signal, wherein said signal is configurable to adapt said first rate of transmission from said frame based data channel interface, to a second rate.
2. The method according to claim 1 , wherein said data is received directly from an Ethernet local area network.
3. The method according to claim 1 , wherein said network comprises a synchronous digital hierarchy (SDH) network.
4. The method according to claim 1 , wherein said network comprises a SONET network.
5. The method according to claim 1 , wherein said step of receiving said frame based data comprises receiving one or more pause frames generated by a local area network switch.
6. The method according to claim 1 , wherein said buffer comprises data storage locations configurable to store at least one data frame.
7. The method according to claim 1 , wherein said buffer comprises a size equal to a number of maximum length Ethernet frames, said number being selectable from a set comprising 4 and 6.
8. The method according to claim 1 , wherein said buffer is configured as a first in first out (FIFO) queue.
9. The method according to claim 1 , wherein said buffer is configured as a circular buffer.
10. The method according to claim 1 , wherein said step of monitoring said amount of transmitted frame based data received, comprises determining if said amount is less than said threshold level.
11. The method according to claim 1 , wherein said signal is generated and sent to said local interface if said amount of said frame based data received is not less than said threshold level.
12. The method according to claim 1 , wherein if said amount of said frame based data received is not less than said threshold level, then a decision to generate said signal is made substantially immediately.
13. The method according to claim 1 , wherein if said amount of said frame based data is not less than said threshold level then said signal is transmitted to said local interface upon another frame, currently being transmitted to said local interface, being completed.
14. The method according to claim 1 , wherein said signal comprises a pause frame specifying a predetermined time interval for inhibiting further transmissions from said local frame based data channel interface.
15. The method according to claim 1 , wherein said buffer comprises, above said threshold level, an amount of data storage capacity equal to the size of two maximum length Ethernet frames.
16. A method of using a synchronous digital multiplexer unit for controlling flow of frame based data, received from a synchronous digital network, to a frame based data channel interface, comprising steps of:
receiving said frame based data at a first rate;
configuring a buffer to receive said frame based data;
predetermining a data amount threshold level for said buffer;
with respect to said threshold level, monitoring an amount of said frame based data received; and
in response to said step of monitoring said amount of said data received, generating a signal, wherein said signal is configurable to adapt said first rate of transmission of said frame based data from said synchronous digital network to a second rate.
17. The method according to claim 16 , wherein said network comprises a synchronous digital hierarchy network.
18. The method according to claim 16 , wherein said network comprises a SONET network.
19. The method according to claim 16 , wherein said step of receiving said frame based data comprises receiving one or more pause frames.
20. The method according to claim 16 , wherein said buffer comprises data storage locations configurable to store at least one data frame.