Multiplex communications – Communication techniques for information carried in plural... – Adaptive
Reexamination Certificate
1998-03-16
2001-05-29
Patel, Ajit (Department: 2661)
Multiplex communications
Communication techniques for information carried in plural...
Adaptive
C370S323000, C370S391000, C370S395430
Reexamination Certificate
active
06240102
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to techniques for routing a UBR (Unspecified Bit Rate) connection in an ATM (Asynchronous Transfer Mode) network.
2. Description of the Related Art
In recent years, the development of ATM networks has been promoted, and the principal purpose thereof consists in expediting existing LANs (Local Area Networks). In this regard, LAN data are transmitted through UBR connections within the ATM network in most cases. It is therefore conjectured that messages based on UBR connections will form a great majority of the traffic on an ATM network.
Accordingly, how to efficiently set the UBR connections becomes important when improving effective load distribution and utilization of resources, etc. in the ATM network.
The features of the UBR connection are as listed below:
(1) The UBR connection has the lowest quality among the four service categories of a CBR (Continuous Bit Rate) connection, a VBR (Variable Bit Rate) connection, an ABR (Available Bit Rate) connection and the UBR connection.
(2) The network does not guarantee a bandwidth requested by the user thereof.
(3) A request for a transmission quality is not be made by the user.
(4) On account of the above property (2), the network does not administer the bandwidths of the UBR connections.
In general, in determining a route for a connection, an ATM exchange checks the physical conditions (such as the occurrence of any fault) of communication lines including the route therein, it acquires a requested bandwidth on the route, it reserves connection resources on the route, and it secures a requested quality on the route. As indicated in
FIG. 1
, however, it is the actual situation of a UBR connection that only two factors; the check of the physical conditions of the lines including the UBR connection route therein, and the reservation of the connection resources on the route, are used for the determination of the route on account of the properties (1)-(4) of the UBR connection mentioned above.
For this reason, such UBR connections might be concentrated on a single route insofar as the physical conditions of the lines including the route therein are normal and as the connection resources on the route are still in surplus (that is, as the number of connections set on the route is smaller than the upper limit of connections).
Accordingly, the present-day system for routing a UBR connection has the problem that effective load distribution and utilization of resources cannot be improved in an ATM network.
SUMMARY OF THE INVENTION
The present invention has been made with the background stated above, and its object is to provide a system for routing a UBR connection to improve effective load distribution and utilization of resources in an ATM network.
The present invention is based on a system for routing an unspecified bit rate connection (UBR connection) wherein a route is determined by administering neither a bandwidth nor a quality in a cell network (ATM network) for communicating cells of fixed length (ATM cells) each of which is autonomously routed on the basis of route information set in a header part of the cell.
The first aspect of the performance of the present invention is configured as explained below.
An exchange constituting the cell network administers the number of unspecified bit rate connections for every resource included in the exchange.
Further, the exchange determines the route of the unspecified bit rate connection on the basis of the number of the unspecified bit rate connections administered for every resource included in the exchange.
As a result of the above configuration of the first aspect of the performance of the present invention, effective load distribution and utilization of the connection resources in the network are improved in the case of routing the unspecified bit rate connection in each resource of an ATM network system etc. which is based on a signaling protocol called the “IISP (Interim Inter-switch Signaling Protocol)” and approved by the ATM Forum.
The second aspect of the performance of the present invention is configured as explained below.
A constituent exchange of the cell network administers the number of unspecified bit rate connections for every resource included in the exchange.
Further, the constituent exchange possesses a database in which information on the numbers of unspecified bit rate connections of the respective resources included in all constituent exchanges of the cell network are stored in such a way that the constituent exchange and another constituent exchange of the cell network occasionally interchange the information on the numbers of unspecified bit rate connections of the respective resources included in both the exchanges and administered by both the exchanges.
Further, the constituent exchange of the cell network determines the route of the unspecified bit rate connection on the basis of the stored contents of the database possessed by this exchange.
As a result of the above configuration of the second aspect of the performance of the present invention, effective load distribution and utilization of the connection resources in the network are improved in the case of routing the unspecified bit rate connection in each resource of an ATM network system etc. which is based on a signaling protocol called the “P-NNI (Private-Network to Network Interface)” which is being standardized by the ATM Forum.
Each of the above configurations according to the present invention can be so configured that the number of the unspecified bit rate connections which use each resource or line port included in the exchange is set to a specific value indicative of congestion or a fault when the congestion or the fault has occurred in the resource or line port.
As a result, the selection of any route where the congestion or the fault currently occurs can be avoided in the case of routing the unspecified bit rate connection.
REFERENCES:
patent: 5675576 (1997-10-01), Kalampoukas et al.
patent: 5742594 (1998-04-01), Natarajan
patent: 5812527 (1998-09-01), Kline et al.
patent: 5889779 (1999-03-01), Lincoln
patent: 5898669 (1999-04-01), Shimony et al.
patent: 5940396 (1999-08-01), Rochberger
patent: 5982748 (1999-11-01), Yin et al.
patent: 6041038 (2000-03-01), Aimoto
patent: 738571 (1995-02-01), None
Fujitsu Limited
Helfgott & Karas P.C.
Patel Ajit
Phunkulh Bob A.
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