Multiplex communications – Fault recovery – Bypass an inoperative station
Reexamination Certificate
1998-02-20
2001-05-15
Vincent, David R. (Department: 2661)
Multiplex communications
Fault recovery
Bypass an inoperative station
C370S535000
Reexamination Certificate
active
06233221
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates generally to the field of telecommunications and, in particular, to a system and method for a ring network with virtual path connections.
BACKGROUND OF THE INVENTION
The telecommunications industry traditionally has provided services to subscribers over narrowband circuits. These narrowband circuits provided acceptable performance when the bulk of the demand for telecommunications services was predominantly for voice traffic. In recent years, additional telecommunications services have been developed that can use much higher bandwidth, e.g., Internet access, video conferencing, corporate intranets. These “broadband” services are increasingly in demand. Unfortunately, the existing telecommunications networks are not designed to provide quality broadband services.
As the demand for access to telecommunications services increased, the industry used time division multiplexing technology to aggregate a number of lower bandwidth circuits onto higher bandwidth circuits. By the middle 1980's, the SONET standard was well established as a time division multiplexing technology for fiber optic transport systems. However, as anyone who has attempted to download a large data file over the Internet can attest, current broadband services do not operate well over the existing telecommunications infrastructure.
The telecommunications industry has been developing approaches that will allow better use of bandwidth in a broadband network. For example, Bellcore, with the assistance of others in the telecommunications industry, has provided standards for transmitting asynchronous transfer mode (ATM) packets over a SONET ring network. See, e.g., GR-2842 and GR-2837. These standards are incorporated herein by reference. These standards specify transmission of data between endpoints in a ring network over virtual circuits.
However, the standards do not speak to all issues relating to a ring network for carrying ATM traffic. First, the standards do not specify how to prevent a single point of failure from bringing down the network element and the network. Further, the standards do not address how to interconnect two sub-networks so that a single point of failure in one sub-network does not interfere with the operation of the second sub-network.
For the reasons stated above, and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for a ring network with virtual connections that survives single point of failure and that can interconnect with other ring networks without interfering with the operation of the other ring networks.
SUMMARY OF THE INVENTION
The above mentioned problems with telecommunications networks and other problems are addressed by the present invention and will be understood by reading and studying the following specification. A system and method for a ring network with virtual path connections is described which uses first and second ring interface modules to process packets on first and second routes of a ring network. The ring interface modules by-pass a local bus at a network element when a packet received from the ring is destined for an endpoint associated with another network element. Further, ring interconnection modules are provided which allow packets from either route of one network to be communicated to a second network such that a point of failure in one route of the first network will not cause path switching in the second network but cause path switching in the ring interconnection module in the first network.
In particular, an illustrative embodiment of the present invention includes a network element for a virtual path ring network. The network element includes a first ring interface module with a ring input and a ring output. Further, the network element includes a second ring interface module with a ring input and a ring output. A first bus is coupled to the first ring interface. A second bus is coupled to the second ring interface. The first and second ring interface modules each include a switch fabric that passes packets from the ring input of the interface module to its ring output for packets with a destination address for an endpoint associated with another network element. The switch fabrics of the first and second ring interfaces further pass packets from the ring input to the first and second buses, respectively, for packets with destination addresses for endpoints that are associated with the network element. An access interface module is coupled to the first and second buses that adds and drops traffic to and from the ring network.
In another embodiment, a method for processing packets in a network element of a virtual path ring network is provided. The method includes receiving packets from the ring. A destination address of the packet is read. The method looks in a routing table for the destination address read from the packet. When the destination address corresponds to an endpoint associated with the network element, the method switches the packet to a bus of the network element. When the destination address corresponds to an endpoint that is not associated with the network element, the method switches the packet back out onto the ring.
In another embodiment, a method for interconnecting at least two virtual path sub-network rings so that a failure in one sub-network does not cause protection switching in another sub-network is provided. The method includes comparing packets from first and second routes of one sub-network with a first interconnection module. Packets from one of the first and second routes are selected based on the comparisons. The selected packets are transmitted to another sub-network for transmission on one of the routes of the other sub-network.
In another embodiment, a virtual connection network with a protected ring interconnection between sub-network rings is provided. The network includes a first sub-network that includes a number of network elements coupled to form a ring including first and second routes for transmitting packets around the sub-network. At least one additional sub-network is also provided. The at least one additional sub-network includes a number of network elements coupled to form another ring also including first and second routes for transmitting packets around the at least one additional sub-network. A first interconnection module is associated with the first sub-network. The first interconnection module selectively passes packets from one of the first and second routes of the first sub-network to the first route of the at least one additional sub-network. Further, the first interconnection module also passes packets from one of the first and second routes of the at least one additional sub-network to the first route of the first sub-network. A second interconnection module is also provided. The second interconnection module is associated with the first sub-network and selectively passes packets from one of the first and second routes of the first sub-network to the second route of the at least one additional sub-network. Further, the second interconnection module passes packets from one of the first and second routes of the at least one additional sub-network to the second route of the first sub-network.
In another embodiment, a virtual path network is provided. the network includes a first sub-network that includes a number of network elements coupled to form a ring including first and second routes for transmitting data around the network. At least one additional sub-network is provided that includes a number of network elements coupled to form another ring also including first and second routes for transmitting data around the network. A first ring interconnection module interconnects the first sub-network with one of the routes of the second sub-network. A second ring interconnection module interconnects the first sub-network with the other route of the second sub-network.
REFERENCES:
patent: 4677611 (1987-06-01), Yano
Lowe Gregory D.
Zheng Dan
ADC Telecommunications Inc.
Fogg Slifer & Polglaze, PA
Vincent David R.
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