Claims
- 1. A control device for a cascade connection of a multiplicity of network units, the control device including an up port and a down port and control logic for sending and receiving control messages to and from the up port and the down port, the control logic including:
means for incrementing a count value in a control message received at the down port to provide for the up port a control message including an incremented count; means responsive to a control message including a count value received at the up port to provide a corresponding control message for the down port; means responsive to the absence of reception of valid control messages at the down port to initiate a count for a control message at the up port; and means responsive to the absence of reception of valid control messages at the up port to determine a total count value in a control message for the down port.
- 2. A control device according to claim 1 and including means for receiving and transmitting control messages on the same line from each of the up port and down port.
- 3. A control device according to claim 1 wherein the control logic provides for the up port a control message defining an invalid count until a valid count is detected in a control message received at the down port.
- 4. A control device according to claim 3 wherein the control logic provides for the down port, in the absence of reception of valid control messages at the up port, and in the absence of a valid count in a control message at the down port, a control message defining an invalid count total.
- 5. A stack of network units including:
a multiplicity of multi-port network units; a cascade connection for the conveyance of data packets from each of said multi-port network units to the other multi-port network units in the stack; and for each multi-port network unit a respective cascade control device, each respective cascade control device comprising:
an up port and a down port and control logic for sending and receiving control messages to and from the up port and the down port, the control logic including, means for incrementing a count value in a control message received at the down port to provide for the up port a control message including an incremented count, means responsive to a control message including a count value received at the up port to provide a corresponding control message for the down port, means responsive to the absence of reception of valid control messages at the down port to initiate a count for a control message at the up port, and means responsive to the absence of reception of valid control messages at the up port to determine a total count value in a control message for the down port, whereby the cascade control devices establish for said network units respective identification numbers corresponding to successive values of the count and an active unit total corresponding to said total count value.
- 6. A stack according to claim 5 wherein each cascade control device includes means for receiving and transmitting messages on the same line from each of the up port and down port.
- 7.A stack according to claim 5 wherein said control logic provides for said up port a control message defining an invalid count until a valid count is detected in a control message received at said down port and further provides for said down port in the absence of reception of valid control messages at said up port, and in the absence of a valid count in a control message at the down port, a control message defining an invalid count total.
Priority Claims (1)
Number |
Date |
Country |
Kind |
0026625.4 |
Nov 2000 |
GB |
|
CROSS-REFERENCE TOP RELATED APPLICATION
[0001] Poulter et al, Ser. No. 09/662,158 filed Aug. 1, 2000, entitled ‘CASCADE CONTROL ARCHITECTURE AND OPERATION FOR PACKET-BASED COMMUNICATION SYSTEMS’ and commonly assigned herewith.
[0002] This invention relates to the cascade connection of a plurality of ‘stackable’ units for a packet-based communication system. The invention more particularly relates to the physical architecture of the control path for such a cascade connection and the intercommunication of control messages for units which participate in the cascade