Multiplex communications – Data flow congestion prevention or control – Control of data admission to the network
Reexamination Certificate
1999-07-29
2002-10-22
Ngo, Ricky (Department: 2664)
Multiplex communications
Data flow congestion prevention or control
Control of data admission to the network
C370S395430, C370S468000
Reexamination Certificate
active
06469982
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method to share available bandwidth, a processor realizing such a method and a scheduler, an intelligent buffer and a telecommunication system.
Such a method to share available bandwidth is already known in the art, e.g. from the article “A flexible buffer acceptance algorithm to support a guaranteed frame rate service category in asynchronous transfer mode ATM switches” written by O. Bonaventure and presented at IFIP ATM 98 workshop, Jul. 20-22, 1998 pages 77/7 to 71/10. Therein, a flexible buffer acceptance algorithm to support the Guaranteed Frame Rate GFR service category in Asynchronous Transfer Mode switches is described. The GFR service is one of the service categories which are specified for different kind of network applications. For each kind of service, a set of parameters is given in order to describe the traffic presented to the network and the Quality of Service which is required of the network. In order to meet the desired QOS objectives different kind of traffic control mechanisms are defined.
A method to share available bandwidth on a common link in a communication network among a plurality of data flows which are transmitted via the common link is described in this article, in particular, for the guaranteed frame rate GFR service. It is described in this article that the objective of the Guaranteed Frame Rate GFR service category is to provide a service with a minimum guaranteed bandwidth which is easy to use for the end-systems. While no modifications are strictly required to the end-systems to benefit from the guaranteed frame rate GFR service category, particular functional blocks such as switches or routers must be enhanced to support this service category.
Indeed, in section 2 of the above mentioned paper it is mentioned that the main motivation behind the introduction of the GFR service category was to keep the simplicity of the Unspecified Bit Rate service category UBR while providing a better service by allowing a minimum guaranteed bandwidth to be associated with each virtual connection, called in this application data flow, which make use of such a common link. A traffic contract for such a GFR service includes the definition of a Minimum Cell Rate MCR for each data flow. Such a minimum cell rate MCR corresponds to a minimum guaranteed bandwidth, expressed e.g. in cells per second. The minimum guaranteed bandwidth is the minimum bandwidth which is guaranteed at any time for each established data flow following its contract and is determined during connection set-up of the data flow. This means that the guaranteed bandwidth is available on the common link for each established data flow and that it is used or not used for this established data flow.
In this way, a method to share available bandwidth on a common link includes a step of sharing reserved bandwidth included in the available bandwidth among the plurality of data flows. A possible way to share the available bandwidth, as it is described in the article for the GFR service, is in function of its minimum cell rate MCR.
It has to be remarked that, as it is also mentioned in the article, the available bandwidth which is shared among the data flows in proportion to their MCR is not necessarily a constant bandwidth. Indeed, in addition to the GFR service category, an e.g. ATM switch might be able to support other service categories. In such a multi-service switch, the available bandwidth to the GFR service data packet streams is not constant anymore but depends on the amount of higher priority traffic e.g. real-time traffic. This means that the total bandwidth over the common link might be bigger and distributed to other kinds of services like real time services whereof in time delivery of the packets is important. It has to be understood that connection admission control algorithms ensure that a predefined average bandwidth is always available to the GFR data flows above the sum of the different minimum cell rates of all GFR data flows.
It is also mentioned in the article that the GFR service also provides the advantage to the end-system to transmit data packets, which are included in such a data flow, in excess of the minimum cell rate MCR being associated to its data flow. A method to share available bandwidth which is mentioned in the article of paragraph 7.1, i.e. the Double EPD mechanism, has however the drawback that the allocation of the excess bandwidth, called unreserved bandwidth can not be controlled at all. On the other hand, paragraph 7.3 of the article mentions two algorithms which are controlling this unreserved bandwidth: one implementation provides a fair allocation of the unreserved bandwidth and another implementation distributes the unreserved bandwidth in proportion to the MCR of the data flows. In this way, a method to share available bandwidth on a common link includes a step of sharing unreserved bandwidth, which is in excess of the reserved bandwidth, according to a respective unreserved data packet share which is associated to each one of the data flows.
A drawback of these prior art algorithms is that they are however sharing the unreserved bandwidth following a particular strategy e.g. fair share for all data flows or a share in function of their minimum cell rate MCR. This means that the unreserved data packet share is predefined by the known algorithms. There is no flexibility for the network operators to define their own policies for sharing the excess bandwidth.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a method to share available bandwidth such as the above known types but which provides to the network operator the flexibility to define their own policies for sharing the unreserved bandwidth.
According to the invention, this object is achieved by the method to share available bandwidth, and a processor realizing the method, and a scheduler, a intelligent buffer and a telecommunication system including such a processor.
Indeed, due to the fact that the step of sharing the unreserved bandwidth includes associating to one of the data flows a respective adaptable administrative weight and the step of determining the respective unreserved data packet share of this data flow in function of its respective adaptable administrative weight, the network operator has the ability, in addition to the sharing of the reserved bandwidth, to provide administrative weights for each data flow. These administrative weights are reflecting the operator's policy to share the unreserved bandwidth.
The flexibility of the proposed method of the invention allows the network operator not only to support the policies of the prior art solutions, i.e. providing a fair allocation or distribution of the unreserved bandwidth following the minimum cell rates of the data flows, but also to define its own policy e.g. an operator can favor its own local network traffic over transit traffic coming from another network.
It has to be explained that different kinds of implementations are possible in order to translate a share of the unreserved bandwidth. Indeed, the adaptable administrative weight can be implemented by a “weight” of the unreserved bandwidth, i.e. a percentage of the unreserved bandwidth e.g. adaptable administrative weight equal to 30%; but another implementation can be translated by a “rate” e.g. data packet rates in proportion to each other. This will become more clear in the following paragraph.
The adaptable administrative weights can be used by the network operator in order to give a different fraction of the unreserved bandwidth to the different data flows.
A first example is given in the event when the network operator wants that all the data flows receive a same fraction of the unreserved bandwidth, then the operator enters for all the data flows a same adaptable administrative weight e.g. 1.
A second example is given in the event when the network operator wants to distribute the unreserved bandwidth in proportion to the minimum guaranteed bandwidth, the adaptable administrative wei
Barri Peter Irma August
Bonaventure Olivier
Desmet Emmanuel
Henrion Michel André Robert
Verkinderen Johan Gabriël August
Alcatel
Ngo Ricky
Sughrue & Mion, PLLC
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