Multiplex communications – Pathfinding or routing – Switching a message which includes an address header
Reexamination Certificate
1998-06-12
2003-03-18
Olms, Douglas (Department: 2661)
Multiplex communications
Pathfinding or routing
Switching a message which includes an address header
C370S254000
Reexamination Certificate
active
06535517
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
The present invention relates in general to the telecommunications field, and in particular, to a method and system for implementing a Network Access Server (NAS) in association with a telecommunications switch.
2. Description of Related Art
Access to the Internet is increasingly desirable to achieve economic, educational, and communicative purposes. Individuals typically access the Internet from a personal electronic device such as a computer, personal digital assistant, or cellular phone. Subscribers in a public telephone network establish data connections to the Internet over a NAS. The data connections to an NAS are established over Plain Old Telephone Service (POTS) phone lines or Integrated Services Digital Network (ISDN) lines. At the subscriber end, normal POTS modems or ISDN network terminals (NT-Is, for network terminals on an ISDN connection) are used to initiate the communications. Personal computers with suitable communications software and hardware are frequently used as the terminal in conjunction with either a modem or NT-I.
The NAS acts as a router and concentrator for Internet Protocol (IP) packets that arrive via the data connections. The link level of the incoming data connections can also be terminated at the NAS. For analog lines, such as those originating with a POTS modem, modem pools may be provided at the NAS. IP packets are forwarded to an Internet gateway through various possible channels from the NAS. The IP packets are then transported over the Internet to the appropriate Internet destination.
In summary, an NAS accepts modem or ISDN calls to an Internet service provider (ISP), terminates the phone connection, and interprets the link layer protocol, e.g., Point to Point Protocol (PPP). The IP data packets are then forwarded to the Internet or possibly an intranet.
An NAS typically has an internal network for receiving and routing packets to the Internet. The internal network includes both electronic devices and one or more edge routers (e.g., an Internet Point-of-Presence, or INET-POP). The electronic devices are important for terminating the phone line connection and reformatting a subscriber's data to comport with the Internet protocol. Conventional internal networks, however, cannot be monitored efficiently to maintain adequate levels of reliability.
Conventional routing protocols for the internal network can enable each electronic device to know which electronic devices and edge router(s) exist on the internal network. Unfortunately, such conventional protocols are dynamic in nature. With these conventional protocols, consequently, the internal network is unaware of which electronic devices should be on the internal network. Installation problems, for example, cannot be recognized or guarded against.
Furthermore, conventional routing protocols do not provide adequate information. For example, in a normal stand-alone NAS, a phone exchange will not be informed about possible internal network problems. One possible internal network problem is that an electronic device does not have a proper connection to a router that is responsible for forwarding an IP packet to the Internet, e.g., an edge router. Because these conventional routing protocols do not provide this information, the phone exchange may select an electronic device that has no actual connection to the Internet. As a result, a subscriber will not be able to access the Internet because the phone exchange has assigned such an electronic device.
Therefore, conventional routing protocols and related apparatus do not (i) provide information regarding an expected internal network topology (e.g., how many and which devices populate the internal network) or (ii) properly communicate a current status to an associated telephone switch.
SUMMARY OF THE INVENTION
The present invention provides a method and apparatus in broadcast networks for combining dynamic connectivity information with expected connectivity information to enable the detection of faulty devices. When a deviation from expected connectivity occurs, the deviation can be detected and responses taken either to avoid attempting to use a faulty device and/or to notify a network operator of the faulty device.
In a preferred embodiment, an NAS in association with a telecommunications switch includes a group of processing devices. The processing devices provide formatting changes for data being transmitted from the public telephone network to a private network such as the Internet and vice versa. The processing devices are interconnected via an Ethernet network and include a router that is a gateway to the Internet.
The expected network topology (e.g., the number and/or location of the processing devices) is initially specified. During operation of the NAS, the current network topology is periodically verified to be equivalent to the specified expected network topology. Deviations are detected when a given processing device fails to hear a “heartbeat” from every other processing device that is expected to be on the Ethernet network over a predetermined threshold period.
Problem counts are received from each processing device on the Ethernet network and a determination is made as to the faulty device or connection. This faulty device or connection is then reported to a network operator's terminal and/or used to route calls. Both incoming and current calls can be routed away from the faulty device or connection to ensure that public telephone network subscribers gain access to the Internet.
An important technical advantage of the present invention is that it enables an NAS to inform telephone network operators of installation problems.
Another important technical advantage of the present invention is that it provides the ability for an NAS to inform operators of current hardware or software problems.
Yet another important technical advantage of the present invention is that an NAS can prevent the visibility of connectivity problems to dial up subscribers by routing their calls only to the devices with good network connections.
Yet another important technical advantage of the present invention is that expected device connections are recorded, and these expected connections are periodically compared with actual current connections.
Yet another important technical advantage of the present invention is that a telephone network exchange can analyze the results of the comparison and respond accordingly so that dial-up subscribers are not connected to inactive devices.
The above-described and other features of the present invention are explained in detail hereinafter with reference to the illustrative examples shown in the accompanying drawings. Those skilled in the art will appreciate that the described embodiments are provided for purposes of illustration and understanding and that numerous equivalent embodiments are contemplated herein.
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Topology Identification for Traffic and Configuration Management in Dynamic Networksby Isabelle Rouvellou and George W. Hart, One World Through Communications, Florence, May 4-8, 1992, vol. 3, No. 11, Jan. 1, 1992, pp. 2197-2204, XP000300346,
Arkko Jari
Brunberg Ralf
Korpela Mika
Toivanen Harri
Jenkens & Gilchrist P.C.
Olms Douglas
Pizarro Ricardo M.
Telefonaktiebolaget L M Ericsson (publ)
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