For a more complete understanding of the present invention, the needs satisfied thereby, and the objects, features, and advantages thereof, reference now is made to the following description taken in connection with the accompanying drawings.
Preferred embodiments of the present invention and their features and advantages may be understood by referring to
Referring to
Referring again to
In operation, traffic nodes 106-114 each may employ a forced upstream forwarding method. Specifically, in a forced upstream forwarding method, each of the traffic nodes includes at least one master upstream port, i.e., one master upstream port or a plurality of master upstream ports, associated with a particular type of traffic, and all or substantially all packets of information that are associated with the particular type of traffic and that are transmitted from the traffic node are transmitted from the traffic node via the master upstream port(s). Consequently, each of the traffic nodes merely has to recognize the type of traffic included in the packet, and do not have to determine the end destination of the packet.
However, in contrast to known forced upstream forwarding methods, in the present invention, an upstream control protocol may be employed to allow each master upstream port associated with a traffic node to be dynamically reassigned during operation of the network in response to changes within the network, e.g., in response to a failure within the network, in response to the current master upstream port being busy, or the like.
For example, referring to
For example, with respect to traffic node 106, when primary upstream node 102 transmits a first indicator message, traffic node 106 may receive the first indicator message on port 106a. Consequently, traffic node 106 knows that port 106a currently is the master upstream port with respect to the predetermined type of traffic. Moreover, port 106a continues to operate as the master upstream port for traffic node 106 with respect to the predetermined type of traffic until traffic port 106 receives an indicator message from primary upstream node 102 on a port other than port 106a. For example, if traffic node 106 receives a second, a third, a fourth and a fifth indicator message on port 106a, and then receives a sixth indicator message on port 106b, port 106b will operate as the master upstream port with respect to the predetermined type of traffic after traffic node 106 receives the sixth indicator message on port 106b. Port 106b then continues to operate as the master upstream port for traffic node 106 with respect to the predetermined type of traffic until traffic port 106 receives an indicator message from primary upstream node 102 on a port other than port 106b.
As described above, primary upstream node 102 may be configured to transmit periodic indicator messages to secondary upstream node 104 and to each of traffic nodes 106-114, and the indicator message indicates that primary upstream node 102 currently is operating as the master upstream node for network 100 with respect to the particular type of traffic. However, during operation, there may be network failures that affect primary upstream node 102 and that prevent primary upstream node 102 from effectively operating as the master upstream node with respect to the particular type of traffic. Therefore, in one embodiment of the present invention, secondary upstream node 104 is configured to operate as the master upstream node with respect to the particular type of traffic when primary upstream node 102 is not able to operate as the master upstream node with respect to the particular type of traffic.
For example, in one embodiment, when secondary upstream node 104 receives an indicator message from primary upstream node 102 and then a predetermined amount of time expires without secondary upstream node 104 receiving another indicator message from primary upstream node 102, secondary upstream node 104 may take over as the master upstream node with respect to the particular type of traffic. Specifically, when the predetermined amount of time expires without secondary upstream node 104 receiving another indicator message from primary upstream node 102, it is likely that there is a failure that is preventing primary upstream node 102 from operating as the master upstream node for network 100 with respect to the particular type of traffic.
In another embodiment, secondary upstream node 104 may be configured to transmit periodic status messages to primary upstream node 102, and primary upstream node 102 may be configured to transmit a response to such status messages indicating that primary upstream node 102 still is operating as the master upstream node for network 100 with respect to the particular type of traffic. However, if primary upstream node 102 fails to timely respond to one of the status messages, or if primary upstream node 102 transmits a response to one of the status messages indicating that primary upstream node 102 is unable to operate as the master upstream node with respect to the particular type of traffic, then secondary upstream node 104 may take over as the master upstream node with respect to the particular type of traffic. In any of these embodiments of the present invention, when secondary upstream node 104 takes over as the master upstream node with respect to the particular type of traffic, secondary upstream node 104 performs all of the functions formerly performed by primary upstream node 102. Moreover, when primary upstream node 102 is again able to operate as the master upstream node with respect to the particular type of traffic, secondary upstream node 104 will receive an indicator message from primary upstream node 102 and/or a response to a status message from primary upstream node 102, and primary upstream node 102 will resume operation as the master upstream node with respect to the particular type of traffic.
Referring to
Moreover, in step 214, an indicator message is transmitted from the primary upstream node to each of the plurality of traffic nodes and to the secondary upstream node indicating that the primary upstream node currently is operating as a master upstream node for the network with respect to the predetermined type of traffic. Specifically, the master upstream node is configured to receive all packets of information within the network that are associated with the predetermined type of traffic, such that the master upstream node operates as an exit node for the network with respect to the predetermined type of traffic. If the primary upstream node is not able to operate as the master upstream node with respect to the particular type of traffic, then the secondary upstream node is configured to operate as the master upstream node with respect to the particular type of traffic until the primary upstream node is again able to operate as the master upstream node with respect to the particular type of traffic.
In step 216, for each of the traffic nodes, it is determined which port or ports received the indicator message from the master upstream node. Specifically, all packets of information that are associated with the predetermined type of traffic and that are transmitted from the traffic node are transmitted via the master upstream port. The method then returns to step 214. In this manner, the master upstream port for each of the traffic nodes may be dynamically reassigned during operation of the network in response to changes within the network, e.g., in response to a failure within the network, in response to the current master upstream port being busy, or the like.
While the present invention has been described in connection with preferred embodiments, it will be understood by those skilled in the art that variations and modifications of the preferred embodiments described above may be made without departing from the scope of the invention. Other embodiments will be apparent to those skilled in the art from a consideration of the specification or from a practice of the invention disclosed herein. It is intended that the specification and the described examples are considered exemplary only, with the true scope of the invention indicated by the following claims.