Multiplex communications – Data flow congestion prevention or control – Control of data admission to the network
Reexamination Certificate
2000-06-21
2004-11-16
Marcelo, Melvin (Department: 2663)
Multiplex communications
Data flow congestion prevention or control
Control of data admission to the network
C370S392000
Reexamination Certificate
active
06819652
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an improved communications system and in particular to a method and apparatus for processing control messages in a communication system. Still more particularly, the present invention provides a method and apparatus for processing control messages through a packet-based portion of a communications system.
BACKGROUND OF THE INVENTION
Voice communications over packet-based networks are becoming more common within communications systems. Currently, many of these networks are Internet Protocol (IP) networks. These voice communications are referred to as voice over IP or VoIP. The use of these networks for communications takes advantage of resources already in place. Further, companies with Internet systems also may implement voice over IP communications using their existing network systems. Further, in addition to voice, the presence of a packet-based network allows for various services to be offered based on the packet-based technologies, such as, for example, providing e-mail messages and documents across the same terminal device.
One problem with a packet-based network system used for voice is the fact that IP networks, such as the Internet, consists of multiple routers, which are linked together. These routers store the data packets and forward them to the most appropriate output links, which may range from 64 kilobits per second over a twisted pair to 155 megabits per second or greater over fiber based links.
IP is a datagram-based approach and offers no guarantee of quality. For example, network delay may be variable depending on the traffic within the network. In an IP network, packets are self-steering and dependant on the IP address. As a result, packets may take different routes depending on how busy each router is within a network. In contrast, with a fixed circuit, the delay is fixed and known. A further problem with IP networks is that depending on the traffic within a network, packets may be dropped. For transmission of data, packets may be resent. As a result, the packets retransmitted are delayed more than other packets taking the same route, which are not dropped. This retransmission mechanism is appropriate for applications, which are insensitive to delays. These mechanisms are commonly used in applications, such as, for example, Web browsers and e-mail programs.
On the other hand, with delay sensitive applications, variable delays and dropping of packets are undesirable. When the delay sensitive application includes transmitting voice data, variable delay or dropping of packets is unacceptable to maintain an appropriate quality of service for a call. Another instance in which the unpredictable delay or dropping of packets is unacceptable occurs as with control messages used to set up, manage, and terminate a session for a call. Currently, no mechanism is present for handling control messages over a packet-based network to guarantee delivery of these messages.
Therefore, it would be advantageous to have an improved method and apparatus for handling control messages in an IP communications system.
SUMMARY OF THE INVENTION
An improved method and apparatus for handling control messages is provided in which priority or preferential processing of these control messages occurs within a packet-based portion of a communications system. More specifically, the present invention provides a method in a communications system for processing control messages for a session in a packet-based network within the communications system. A priority indicator is placed in a control message handling a session within the communications system through the packet-based network. Applications handling control messages in the packet-based network will provide priority or preferential handling of the control message containing the priority indicator.
In the depicted examples, some nodes contain applications, which handle control messages, while other nodes only handle packets transporting the control messages and do not process the control messages themselves. In this case, another indicator also may be placed in the header of a packet transporting the control message. This indicator is used by nodes, which handle the packets to provide priority processing of the packets in these nodes. In this manner, the control message may be given priority handling even in nodes in which an application handling control messages is absent. Thus, priority handling of the control message is provided within the packet-based network within the communications system.
Other aspects and features of the present invention will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying figures.
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Akhtar Haseeb
Aravamudhan Lakshminarasimhan
Hosain Akram
Narayanan Raja P.
Qaddoura Emad A.
Marcelo Melvin
Nortel Networks Limited
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