Method and apparatus for overload control in multi-branch packet networks
View Patent ↗A method and apparatus are disclosed for congestion management in a multi-branch Internet Protocol-based private branch exchange switch. The multi-branch Internet Protocol-based private branch exchange switch is interconnected through (i) a packet network referred to as the primary network, such as a wide area network, and (ii) an alternate network, such as the public switched telephone network. Packet phone adapters associated with each packet telephone unit monitor packet telephone calls and report delay information to communication servers. The communication server can reroute the packet telephony calls through the secondary network upon detection of congestion in the underlying primary network, thereby preserving voice quality. The packet phone adapter will discard records collected from calls whose duration is below a minimum value, to ensure reliable congestion information. Each communication server records reported voice quality of service information in a congestion control database. An overload control process processes each call set up request and determines if the requested path is congested. If a requested path is congested, then the overload control process may forward the call using the secondary network.
1. An overload control method for use in a multi-branch Internet Protocol-based private branch exchange system within a network environment having a primary network and at least one alternate network, said method comprising the steps of:
maintaining a congestion indicator status associated with each path in said primary network, said congestion indicator status indicating whether said path is congested and based on congestion data from at least one end unit device that participated in a packet telephony communication;
receiving a call set up request from a source terminal;
determining if a primary path between said source terminal and a destination terminal is congested using said congestion indicator status;
routing said call using said at least one alternate network if said primary path between said source terminal and a destination terminal is congested; and
setting a timer that will cause said congestion indicator status to automatically expire after a predefined period of time, wherein said congestion indicator status and said timer are reset each time said congestion data is received from said at least one end unit device and wherein said timer expires after a period of time within which said congestion is expected to be alleviated.
2. A congestion management method for use in an Internet Protocol-based private branch exchange system within a packet network environment, said method comprising the steps of:
receiving congestion data from at least one end unit device that participated in a packet telephony communication;
determining if said congestion data indicates that a path associated with said packet telephony communication is congested;
setting a congestion indicator flag associated with said path if said congestion data indicates that a path associated with said packet telephony communication is congested; and
setting a timer that will cause said congestion indicator flag to automatically expire after a predefined period of time, wherein said congestion indicator flag and said timer are reset each time said congestion data is received from said at least one end unit device and wherein said timer expires after a period of time within which said congestion is expected to be alleviated.
3. A congestion management method for use by an end unit packet phone adapter in a packet network environment, said method comprising the steps of:
collecting congestion data associated with a packet telephony communication;
determining if said packet telephony communication had a duration that exceeded a predefined threshold; and
reporting said congestion data to a centralized server that performs overload control, whereby said centralized server evaluates said congestion data to determine if a path associated with said packet telephony communication is congested;
and sets a timer that will cause said determined congestion status to automatically expire after a predefined period of time, wherein said determined congestion status and said timer are reset by said centralized server each time said congestion data is reported and wherein said timer expires after a period of time within which said congestion is expected to be alleviated.
4. A congestion manager for use in an Internet Protocol-based private branch exchange system within a packet network environment, comprising:
a memory for storing computer readable code; and
a processor operatively coupled to said memory, said processor configured to:
receive congestion data from at least one end unit device that participated in a packet telephony communication;
determine if said congestion data indicates that a path associated with said packet telephony communication is congested;
set a congestion indicator flag associated with said path if said congestion data indicates that a path associated with said packet telephony communication is congested; and
maintain a timer that will cause said congestion indicator flag to automatically expire after a predefined period of time, wherein said congestion indicator flag and said timer are reset each time said congestion data is received from said at least one end unit device and wherein said timer expires after a period of time within which said congestion is expected to be alleviated.