Geographic redundancy in communication networks
View Patent ↗The present invention provides a redundancy mechanism for packet-based communication environments without requiring localized redundancy of session control entities. These session control entities are generally referred to as service nodes, which may act as proxies on behalf of the communication terminals being served. Instead of having a dedicated backup service node, other active service nodes, which primarily serve different groups of communication terminals, are configured to provide backup support when another service node fails. In operation, a communication terminal will periodically attempt to communicate with its primary service node. When the communication terminal detects that the attempts to communicate with the service node are unsuccessful, the communication terminal will attempt to register with a selected alternate service node, the alternate service node being a currently active service node primarily supporting another group of communication terminals. The alternate service node can then accept and support the communication terminal.
1. A communication terminal comprising:
a user interface;
a communication interface; and
a control system associated with the user interface and the communication interface, the control system adapted to:
periodically attempt to communicate with a first service node, wherein first configuration data identifies the first service node as a default primary service node for the communication terminal and wherein the primary service node is adapted to facilitate communication sessions involving the communication terminal;
detect if an attempt to communicate with the first service node fails; and
when an attempt to communicate with the first service node fails, attempt to associate with a second service node serving as a default primary service node for a first group of communication terminals other than the communication terminal and wherein the second service node is adapted to facilitate communication sessions involving the communication terminal and the first group of communication terminals;
receive from the second service node a redirection message based on an overload condition of the second service node instructing the communication terminal to attempt to associate with a third service node, wherein the redirection message identifies the third service node;
upon receiving the redirection message, successfully associate with the third service node serving as a primary service node for a second group of communication terminals and adapted to facilitate communication sessions involving the communication terminal and the second group of communication terminals;
while associated with the third service node, receive a registration instruction from the third service node, the registration instruction instructing the communication terminal to attempt to associate with the first service node; and
in response to the registration instruction, successfully associate with the first service node in lieu of the third service node.
2. The communication terminal of claim 1 wherein the first service node and the second service node are located apart from one another.
3. The communication terminal of claim 1 wherein the first service node supports first communication terminals generally affiliated with a first geographic region and the second service node supports second communication terminals generally affiliated with a second geographic region separate from the first geographic region.
4. The communication terminal of claim 1 wherein the second service node is not a redundant service node associated with the first service node.
5. The communication terminal of claim 1 wherein the first service node and the second service node are adapted to act as proxies to facilitate communication sessions when associated with the communication terminal.
6. A method comprising:
periodically attempting to communicate with a first service node identified by first configuration data as a default primary service node for a communication terminal and adapted to facilitate communication sessions involving the communication terminal;
detecting if an attempt to communicate with the first service node fails;
when an attempt to communicate with the first service node fails, attempting to associate with a second service node serving as a default primary service node for a first group of communication terminals other than the communication terminal and adapted to facilitate communication sessions involving the communication terminal and the first group of communication terminals;
receiving from the second service node a redirection message based on an overload condition of the second service node instructing the communication terminal to attempt to associate with a third service node, wherein the redirection message identifies the third service node;
upon receiving the redirection message, successfully associating with the third service node serving as a primary service node for a second group of communication terminals and adapted to facilitate communication sessions involving the communication terminal and the second group of communication terminals;
while associated with the third service node, receiving a registration instruction from the third service node, the registration instruction instructing the communication terminal to attempt to associate with the first service node; and
in response to the registration instruction, successfully associating with the first service node in lieu of the third service node.
7. The method of claim 6 wherein the first service node and the second service node are located apart from one another.
8. The method of claim 6 wherein the first service node supports first communication terminals generally affiliated with a first geographic region and the second service node supports second communication terminals generally affiliated with a second geographic region separate from the first geographic region.
9. The method of claim 6 wherein the second service node is not a redundant service node associated with the first service node.
10. The method of claim 6 wherein periodically attempting to communicate with the first service node further comprises sending a register message to the first service node, and detecting if the attempt to communicate with the first service node fails further comprises determining when an acknowledgement to the register message is not properly received.
11. The method of claim 6 wherein the first service node and the second service node are adapted to act as proxies to facilitate communication sessions when associated with the communication terminal.