Multiplex communications – Pathfinding or routing – Switching a message which includes an address header
Patent
1998-09-08
2000-02-08
Vu, Huy D.
Multiplex communications
Pathfinding or routing
Switching a message which includes an address header
H04L 1228
Patent
active
060234687
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process for spacing ATM cells multiplexing several traffic flows of varied profiles and relates also to a device for the implementation thereof.
The invention applies to the management of resources in ATM networks, and more precisely to the "shaping" of the traffic emitted by an ATM source.
2. Discussion of the Background
The source which injects cells into an ATM network may be an ATM user (UNI access, UNI standing for "User Network Interface") or a link-up point between two ATM networks (NNI, standing for "Network Network Interface" or PUNI, standing for "Public User Network Interface").
The sources shape the traffic which they emit under obligation to conform to a compliance contract based on a specific algorithm: the Virtual Spacing Algorithm or GCRA, standing for "Generic Cell Rate Algorithm", a definition of which is given by Recommendation I.371 of the ITU-T (International Telecommunications Union, Telecommunications Section).
With this algorithm it is possible to take two types of traffic profiles into account: traffic at constant bit rate CBR and traffic at variable bit rate VBR. It is based on two parameters: the peak bit rate and the average bit rate.
The peak bit rate is determined by the parameter PCR, standing for "Peak Cell Rate", expressed in cells per second and the average bit rate is determined by the parameters PCR and SCR, standing for "Sustainable Cell Rate", expressed in cells per second, and the parameter MBL, standing for "Maximum Burst Length", expressed in cells defining the maximum length of a burst of cells. The document `A Spacer-Multiplexer for Public UNIs`, P. Boyer & M. Servel, presented during an "ISS'95, World Telecommunications congress" congress, discloses a device which concentrates links emanating from users into a reduced number of high bit rate links directed towards a public network. At the user end, this device polices access and at the network end it carries out the shaping. The shaping function spaces the cells originating from the users with respect to the peak bit rate only. It does not take into account the various qualities of service such as CBR, VBR and UBR, standing for Undefined Bit Rate. The device is output-connected to a single network.
An ATM source multiplexes traffic flows of various kinds. Current solutions do not allow shaping of traffic flows of diverse kinds in order to make them comply with the contract negotiated with a destination network managing a standardized traffic profile. Standardized profiles are the profile with constant bit rate CBR and the profile with variable bit rate VBR.
The purpose of the present invention is to alleviate the aforementioned drawback.
SUMMARY OF THE INVENTION
To this end, the subject of the invention is a process for spacing ATM cells travelling through an ATM switch and emitted by ATM sources multiplexing diverse profiles destined for one or more networks of specified bit rate, characterized in that it consists:
in aggregating the sources emitting cells destined for the same network and in giving the sources a standardized global CBR or VBR profile, the sources being assigned a specified priority,
in taking into account the priorities of each of the sources so as to allow specified qualities of service,
in combining sources multiplexing CBR and VBR profiles so as to obtain a source having a globally VBR or CBR profile, whilst also preserving the characteristics of the sources with CBR profile in the case of a globally VBR profile,
in sharing the passband of the physical link supporting the streams of outgoing cells, between the VBR and CBR profiles, and in allotting the remainder of the passband which is not used up by the above VBR and CBR profiles to so-called complementary sources of UBR profile, standing for Undefined Bit Rate, and
in adapting the bit rate of the sources with globally VBR or CBR profile to the bit rate of a specified physical link through which the outgoing cells must travel in order to access a s
REFERENCES:
patent: 5430721 (1995-07-01), Dumas et al.
patent: 5450225 (1995-09-01), Bostica et al.
patent: 5812527 (1998-09-01), Kline et al.
patent: 5889779 (1999-03-01), Lincoln
Dumas Pierre
Mouen-Makoua David
"Thomson-CSF"
Boakye Alexander
Vu Huy D.
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