Multiplex communications – Pathfinding or routing – Store and forward
Reexamination Certificate
1998-08-11
2003-06-17
Hsu, Alpus H. (Department: 2665)
Multiplex communications
Pathfinding or routing
Store and forward
C370S395200
Reexamination Certificate
active
06580721
ABSTRACT:
TECHNICAL FIELD
This invention relates to the transfer of data between two points and, in particular, to a Universal Transfer Mode of transferring data from a plurality of sources that may operate under different communications protocols to a plurality of sinks using switch modules interconnected by a passive core.
BACKGROUND OF THE INVENTION
Modern telecommunications services are supported by a plurality of networks. The various networks operate under protocols that use packet of various lengths and formats to transfer data between a source and a sink. Modern telecommunications services provide the capability for business and social communications between geographically separated parties. This capability has stimulated a demand for such services and placed a burden on the capacity of existing infrastructure.
In order to increase the capacity for information exchange using the existing infrastructure, there has developed an interest in using asynchronous network facilities such as Asynchronous Transfer Mode (ATM) networks as backbone transport for voice and voice data as well as broadband services. Asynchronous network facilities are preferred for backbone transport because they permit more efficient use of network resources than synchronous transfer mode (STM) facilities. Network cost is therefore reduced. The ATM protocol uses a fixed cell length of 53 bytes. Consequently, packets originating in a network that operates under a different protocol must be deconstructed and packed in ATM cells before they can be transferred through the ATM network. After the packets are transferred through the ATM network, they must be unpacked from the cells and reconstructed before the cells are delivered to a sink. This is a time consuming task that can impact service delivery and quality of service.
Some telecommunications protocols such as Internet Protocol (IP) support packets of variable length. IP is unsuitable for certain telecommunications services, however, because it is connectionless and offers no guaranteed quality of service. Recent work has been done to develop protocols for providing quality of service in IP networks. Resource Reservation Protocol (RSVP) is, for example, one result of such work. Even if quality of service is successfully implemented in IP networks, however, packet addressing and routing in such networks is too processing intensive to permit a high-speed multi-service scalable network to be implemented.
As the demand for telecommunications services increases, service providers seek cost effective methods of service delivery. One way to provide cost effective service delivery is to provide a backbone transport network that is capable of supporting a variety of narrow-band and broadband services so that network provisioning and management costs are shared by a large and diverse user base. Ideally, such a backbone transport network is adapted to support many different telecommunications services and both connection-based and connectionless protocols. To date, no such network is known to have been proposed or described.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide a Universal Transfer Mode (UTM) protocol for transferring telecommunications data in packets from a plurality of sources which may operate under different protocols to a plurality of sinks.
It is a further object of the invention to provide a network specifically adapted to operate under the UTM protocol.
It is yet a further object of the invention to provide a protocol and a network which are adapted to transfer packets of substantially any length without packet fragmentation.
It is yet a further object of the invention to provide a protocol and a network which are adapted to transfer both connectionless and connection-based data traffic.
It is another object of the invention to provide a protocol and a network which are adapted to enable rate regulated data packet transfer in a multi-class data network.
It is yet a further object of the invention to provide a protocol that uses an adaptive header for both control signaling and for payload transfer.
It is yet a further object of the invention to provide a UTM protocol in which the adaptive header is used as a control packet for setting up or tearing down a path, a connection within a path or an independent connection with the UTM network.
It is yet a further object of the invention to provide a UTM protocol in which the adaptive header is parsed by a simple algorithm to determine a function of the header and a destination for packets appended to the header.
It is yet another object of the invention to support the optional subdivision of data in a connection-based data packet into sub-fields to support multi type communications.
It is a further object of the invention to provide methods for establishing connections in a data packet network using real-state or near-real-state routing information.
It is a further object of the invention to provide an apparatus for transfer rate regulation in a UTM network which ensures end-to-end transfer rate regulation in the network.
It is yet a further object of the invention to provide a method and apparatus for controlling provisional connections in a UTM network for the transfer of connectionless or connection-based traffic having no specified transfer rate.
In its simplest aspect, a transfer rate regulation mechanism for a data packet switch switching variable sized packets, comprising:
a) a plurality of queues or buffers containing data packets sorted into traffic streams, the data packets in each traffic stream being associated with one or more logically related communication sessions;
b) a memory for storing a transfer rate allocation of normalized data units for each data stream, the transfer rate allocation being an accumulation of transfer rate allocations assigned to communications sessions in the respective data streams on setup of the communications sessions through a network that includes the data packet switch; and
c) a multi-stage circuit of parallel arithmetic processors, which compute an eligibility for transfer of the data packets in the respective traffic streams, based on the respective transfer rate allocations.
The invention further provides a UTM distributed switch, comprising a plurality of modules, each module interfacing with a plurality of links, the modules accepting data to be routed through universal ports which transfer packets of variable size to others of the plurality of modules; a passive core that logically interconnects each of the modules to each of the other modules and transfers the data between the modules under control of the modules; the traffic between any source and a sink being rate regulated.
The invention also provides a method of transferring telecommunications data in packets from a plurality of sources to a plurality of sinks comprising the steps of accepting a communications admission request from a source at an interface at a module port that operates under a universal transfer mode (UTM) protocol, the communications admission request providing communications admission control parameters required for establishing a communications session between the source and a sink; for a connection-oriented transaction, setting up a connection for the communications session through the UTM network; accepting the packets from the source at the interface and determining a length of each packet; and transferring the packet to an interface that serves the sink using the connection or destination identifier.
The UTM protocol and the UTM network in accordance with the invention provide rate regulated data transfer between a source and a sink. Both connectionless and connection-based traffic may be served. The UTM protocol accommodates a plurality of classes of service, which ensure a quality of service appropriate to the data being transferred. Transfer through the UTM network is accomplished using an adaptive UTM header that is parsed by UTM modules using a simple algorithm that is preferably implemented in hardware. The algorithm determines a purpose
(Ogilvy Renault)
Hsu Alpus H.
Nguyen Toan
Nortel Networks Limited
Wood Max R.
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