Multiplex communications – Fault recovery
Reexamination Certificate
1999-10-15
2001-09-11
Olms, Douglas (Department: 2732)
Multiplex communications
Fault recovery
C370S398000
Reexamination Certificate
active
06289001
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to packet based data communication networks, and more particularly to proxy agent control of asynchronous transfer mode (ATM) networks.
Today, telecommunications continues to shift from an emphasis on circuit switched networks, such as the Public Switched Telephone Network (PSTN) to faster, more flexible packet-based data networks. Internet protocol (IP) and ATM protocol technologies provide the processing bandwidth and speed necessary to communicate real time voice, data, and graphics between end users.
In a typical ATM network supporting voice communication, the ATM network is utilized for interconnecting trunking gateways linked to traditional circuit switched based PSTN networks and/or access gateways linked to telephone users access devices such as analog phones, PBXs, etc. For example, an end user may have a phone set connected to ATM access gateway. The ATM gateway interfaces with the user's phone set and translates the voice into data packets. The gateway then sends the packets to an ATM switch (or a network of ATM switches) for routing. On the other side of the ATM switch, a second access gateway interfaces with the receiving end user and translates the packetized data into a real time voice call for the user.
ATM switches route ATM data packets over virtual circuits. When Switched Virtual Circuits (SVC) are utilized by the ATM network the virtual circuits are established on demand in real time. Thus, for each call, a virtual circuit from the originating end user to a destination end user must be setup by the ATM switch(s). The intelligence for controlling the establishment of these virtual circuits can be included within the ATM switch or within a “proxy agent.” A proxy agent is typically a separate network element connected to both the gateways and the ATM switch to provide the third party signaling necessary to setup and maintain a call connection. Proxy agents communicate with ATM switches and gateways by “proxy signals,” which are received on one or more ports of an ATM switch. Each ATM switch port controls a set of communication circuits within the switch interior to establish virtual circuits to a called party. For example, an ATM switch may include four ports, each of which controls hundreds of communication circuits within the switch. ATM switches typically include a timer for taking down all virtual circuits when a proxy signal control fails. For example, the ATM Forum's UNI proxy signaling standard defines this timer as a configurable timer. (In this application, this timer is designated as T.) Thus, failure of proxy signaling between the proxy agent and an ATM switch port results in termination of many call connections. This, of course, results in reliability problems, a key concern for any network operator. Typically in case of proxy agent failure, control can be redelegated to another port and/or another proxy agent. However, the switch must be manually reconfigured to match the new port to the corresponding circuit connections. This, of course, takes time and reduces network availability.
Therefore, it is desirable to have methods and systems to overcome the disadvantages of proxy agent signaling in data networks, particularly ATM switch-based networks.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to systems and methods for ATM proxy signaling that substantially obviate one or more of the problems due to limitations and disadvantages of the prior art.
In accordance with the purposes of the invention, as embodied and broadly described, the invention comprises a packet-based data network, including, a first switch for controlling connections between end users, and a plurality of proxy agents, each being capable of providing proxy signals to the first switch. One of the plurality of ATM proxy agents includes a proxy agent selector to select one or more proxy agents for providing proxy signals to the first ATM switch. The network also includes a second switch connected to the first switch, the second switch includes a controller to switch from a connection to one ATM proxy agent to a second ATM proxy agent selected by the proxy agent selector when the connection to one ATM proxy agent fails.
In another aspect, the invention comprises an ATM switch for connection to a plurality of proxy agents capable of providing proxy agent signals for another ATM switch, including, input and output ports, a switch fabric, and a controller for switching connections between the plurality of proxy agents in response to selection information.
In another aspect, the invention comprises a method of providing proxy signals from proxy agents to a data packet switch. The method comprises the steps of selecting one of the plurality of proxy agents to provide proxy signals, and switching connection from the one proxy agent to another of the plurality of proxy agents when the connection from the one proxy agent fails.
The above description of the invention and the following description for carrying out the best mode of the invention should not restrict the scope of the claimed invention. Both provide examples and explanations to enable others to practice the invention. The accompanying drawings, which form part of the description for carrying out the best mode of the invention and together with the description, explain the principles of the invention.
REFERENCES:
patent: 5483527 (1996-01-01), Doshi et al.
patent: 5592466 (1997-01-01), Buczny et al.
patent: 5848128 (1998-12-01), Frey
patent: 6111852 (2000-08-01), Leung et al.
patent: 6205557 (2001-03-01), Chong et al.
Giordano Joseph
Olms Douglas
Telcordia Technologies Inc.
Vanderpuye Ken
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