ITU Recommendation I371, 1995. Traffic control and congestion control in B-ISDN. Geneva, Switzerland. 18  Home/Search   Document Not in Database   Summary   Related Articles   Check

....is indeed ON OFF (see, e.g. 28] In general these rates are not known in advance but it is common to provide upper bounds through leaky bucket descriptions which are used to police that source. In the context of ATM the relevant parameters are the sustainable and peak cell rates (SCR, PCR) [29]. While the interpretation of PCR is straightforward, it should be noted that SCR is the maximum permissible average rate over any time window of a prespecified large duration. In what follows we assume that m = SCR (although, in general m SCR) and p = PCR. s n and t n are the current ....

ITU Recommendation I.371, Traffic control and Congestion Control in B-ISDN, Geneva, Switzerland, 1995.

....complex VBR traffic descriptors to characterize its traffic at each period. In addition, lightweight resource allocation protocols can further reduce signaling overhead. For example, ATM block transfer that is being standardized by ITU T allows bandwidth renegotiations on basis of a block of cells [47]. In transmission, the block of cells is enclosed in two resource management (RM) cells. The first RM cell requests network bandwidth and the second one releases bandwidth. At the network node, blocks of cells are handled as basic units, e.g. they are either accepted for transmission or fully ....

ITU-T Rec. I.371, "Traffic Control and Congestion Control in B-ISDN", Petrh, U.K., November 6-14, 1995.

....Rate Algorithm (GCRA) At the multiplexer input, N VCC connections must be conform to the GCRA parameters. For a given set of parameters, we have to adjust the GCRA parameters in order to have a cell loss ratio less than a given value. To begin, let us recall the GCRA role. ATM Forum [29] and ITU [30] have specified a mechanism for the User Network Interface (UNI) which controls the traffic flowing through a VCC connection. This mechanism is the GCRA: it defines a relationship between the PCR and the Cell Delay Variation (CDV) and a relation between the Sustained Cell Rate (SCR) and the Burst ....

ITU, Geneva, Switzerland, Recommendation I.371: Traffic Control and Congestion Control in B-ISDN.

....for a VC for the purpose of providing quality of service (QoS) The reservation process can be either two way or one way. When such a technique is applied to making reservation for a burst of packets (or ATM cells) as in fast reservation protocol (FRP) and its variations (see for example, [8, 9]) it becomes quite similar to fast circuit switching. However, unlike in fast circuit switching, a talk spurt is segmented into many packets cells, and each packet cell (of the burst) over the VC is still stored and forwarded individually. That is, the header of each packet cell will be processed ....

ITU-T Rec. I.371, "Traffic control and congestion control in B-ISDN." Perth, U.K. Nov. 6-14, 1995.

....here the latter point by performing a compared analysis of two correctness proofs obtained separately for a sophisticated real life protocol. More precisely, we propose a comparison between two proofs of the Available Bit Rate (ABR) conformance algorithm, a protocol designed at France Telecom [15] in the context of network communications with Asynchronous Transfer Mode (ATM) The first proof [19, 18] was obtained in the theorem proving framework using Floyd Hoare method of inductive invariants and the proof assistant Coq [7] The second proof [8] was based on the method of reachability ....

....The correctness proof for these approximation algorithms consists in showing that their outputs are never smaller than the outputs computed by the ideal algorithm. More precisely, we focus on an algorithm, called B 0 , due to Christophe Rabadan at France Telecom, now part of the I. 371.1 standard [15]. We describe this algorithm and prove its correctness with respect to the ideal algorithm, using the two methods mentioned above. The plan of the paper is as follows: section 2 gives an informal description of the problem of ABR conformance control and section 3 presents an incremental algorithm ....

ITU-T Recommendation I.371.1. "Traffic control and congestion control in BISDN ", 1997.

.... The second experiment in this section focuses in the domain where condition (5) is valid; in this case the global performance is approximated by equation (6) An important application in this setting is the management of an ABR service environment, recently introduced by the ATM Forum and the ITU [1,3]. Class 1 would then correspond to the aggregate Guaranteed QoS (G QoS) traffic, while class 2 to the collective ABR traffic. The G QoS class is allotted peak rate bandwidth, in contrast to ABR traffic, which uses the remaining available bandwidth [9] Assume that as G QoS connections come and go, ....

ITU Recommendation I.371, "Traffic Control and Congestion Control in BISDN, " Geneva, July 1995.

....In Asynchronous Transfer Mode (ATM) based networks, resource allocation to a connection is based upon a Traffic Contract negotiated between the user and the network during the connection establishment phase. The Traffic Contract, as specified in the June 1992 version of ITU T Recommendation I. 371 [6], is composed of the requested Quality of Service (QoS) the Cell Delay Variation clumping tolerance, and the Source Traffic Descriptor. The Source Traffic Descriptor, which is a subset of the ATM Traffic Descriptor, contains all the traffic parameters which capture the intrinsic behavior of an ....

....objectives in the case of non compliant usage and conformance testing is needed from a legality point of view [5, 4] Some basic requirements for the policing function in Asynchronous Transfer Mode (ATM) based networks have been identified in the June 1992 version of ITU T Recommendation I. 371 [6]. In particular, this function is implemented in the so called Usage (resp. Network) Parameter Control, UPC (resp. NPC) for short, at the TB interface (resp. inter Network Node Interface) However, it seems very unlikely that a unique UPC NPC mechanism will be standardized in the near future. ....

ITU-TS Recommendation I.371 : Traffic control and congestion control in B-ISDN. Geneva, June 1992.

....a high bandwidth link to homes and the desktop, e.g. for interactive multimedia services. It supports different service classes, such as Constant Bit Rate (CBR) Variable Bit Rate (VBR) Unspecified Bit Rate (UBR) and Available Bit Rate (ABR) ATM traffic management or congestion control methods [1] are needed to ensure that quality of service (QoS) parameters such as cell delay and cell loss probability are within the agreed limits. 2 Connection Admission Control (CAC) When a user wishes to establish a connection with another user, his terminal sends a connection set up request to the ....

ITU-T Study Group 13. Traffic Control and Congestion Control in BISDN. Recommendation I.371, ITU-T, Perth, Nov 1995.

....particular link, the output buffer can fill up and cell delay will increase; worse still, cells will even get discarded when the buffer overflows. Such cell delay and cell loss may seriously degrade the quality of users communication sessions. ATM traffic management or congestion control methods [2] are needed to ensure that quality of service (QoS) parameters such as cell delay and cell loss probability are within agreed limits. It is difficult to build an efficient traffic control system because of the diversity in multimedia traffic characteristics, especially since each user has ....

ITU-T Study Group 13. Traffic Control and Congestion Control in BISDN. Recommendation I.371, ITU-T, Perth, Nov 1995.

....of traffic, network resources and quality of service requirements. From CAC to scheduling every network function should take into account these groups. For our traffic control framework we have chosen the parameters in agreement with the standardisation work of ATM Forum [1] 2] and ITU T [8] [9]. According to the goals of this paper the simulation results can be divided into two groups: i) first we show that QoS can be provided with our ARR algorithm for traffic flows which have applied for guaranteed service, and ii) then we examine how much throughput degradation should network endure ....

ITU-T Recommendations I.371. Traffic Control and Congestion Control in B-ISDN. August 1996.

....control of one or more characteristics of the traffic: average bandwidth, peak bandwidth, burstiness, etc. Many UPC algorithms were proposed in the literature [18, 19, 20] the UPC policy adopted in CLASS is the Generic Cell Rate Algorithm (GCRA) specified in the ITU T Recommendation I. 371 [21] and ATM Forum ATM User Network Interface Specification Version 3.0 [22] as a traffic policing mechanism; the traffic shaping function was obtained with an adaptation of the GCRA that delays cells instead of discarding them. The GCRA is described in the flow chart of Fig. 1; it depends on two key ....

....a fairly critical issue, since it can nullify much of the effort done in smoothing the traffic characteristics; the burstiness of the single flow could again increase significantly. This problem has been recognized in general by ITU T for any multiplexing stage, but no solution has been envisaged [21]. In CLASS, the multiplexer polls all the queues Qs i in the same order in each slot, taking the head of the line cell, provided that the transmission time for the cell has been reached. This is a straightforward stage of multiplexing, but 9 Segmentation Message generation VC 1 Segmentation ....

ITU-T Recommendation I.371 "Traffic Control and Congestion Control in B-ISDN", Geneve, Switzerland, 1992

.... time and a k means the actual arrival time of cell k at a single measurement point [5] If PEI identifies the negotiated Peak Emission Interval of the tagged connection, the set of 2 In the Generic Cell Rate Algorithm 1=T is the peak cell rate, denotes CDV (Cell Delay Variation) tolerance [9] 4 theoretical time fc k g k0 is recursively defined as follows: c k 1 = c k PEI if y k 0 a k PEI if y k 0: If the observed cell arrives earlier than its (reference) theoretical arrival time, it follows y k 0 and the cell is considered to belong to a clump . The observed cell ....

ITU-T Recommendation I.371. Traffic Control and Congestion Control in B-ISDN, 1992. Geneve, Switzerland.

....[4] and [19] where the results in [19] are based on the results of the same authors [18] for the single multiplexer case. For a recent introduction to CDV in general and to teletraffic aspects of CDV in particular, we refer to [13] The CDV issue is also investigated by the standardization bodies [14] and ATM Forum [1] In this paper we investigate the point process properties of the departure process of the CBR stream from the multiplexer, under the batch Bernoulli background traffic. As shown in [11] and [5] then the waiting time which the CBR cells experience in the ATM multiplexer ....

ITU-T SG 13 Recommendation I. 371, Traffic Control and Congestion Control in BISDN.

....point so we get the buffer sizes (Q i ) as input parameters to our traffic control method. 2. 2 Traffic Control Parameters The main goal of traffic control is to protect the network and the user in order to achieve network performance objectives with optimum allocation of network resources [2]. To fulfill these objectives QoS requirements, traffic descriptors and network information needed for the generic traffic control functions. We have chosen the following parameters for our traffic control framework which is in agreement with the standardization work of ATM Forum [3, 4] and ITU T ....

....To fulfill these objectives QoS requirements, traffic descriptors and network information needed for the generic traffic control functions. We have chosen the following parameters for our traffic control framework which is in agreement with the standardization work of ATM Forum [3, 4] and ITU T [1, 2]: Connection Traffic Descriptors: Peak Cell Rate (PCR) Cell Delay Variation Tolerance (CDVT) Sustainable Cell Rate (SCR) Maximum Burst Size (MBS) Minimum Cell Rate (MCR) and the conformance definition: the Generic Cell Rate Algorithm (GCRA) 2] Quality of Service Parameters: Cell Loss ....

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ITU-T Recommendations I.371 Traffic Control and Congestion Control in B-ISDN, 1995.

....CBR stream. 1 Introduction In the new standards for the Broadband Integrated Service Digital Network (B ISDN) and its switching and transport mechanism Asynchronous Transfer Mode (ATM) the connection set up procedure includes a negotiation of a traffic contract between the user and the network [14]. At the entrance to the network (UNI) and at the border between networks owned by different operators (NNI) an enforcement, called usage parameter control (UPC) at the UNI and network parameter control (NPC) at the NNI, of the traffic parameters in the traffic contract of each connection will ....

....the instantaneous peak cell rate is allowed to deviate from the peak cell rate declared by T . In ITU a UPC NPC algorithm has not been standardized. However, it is standardized how to measure whether a cell stream is conforming to the traffic contract or not. The Generic Cell Rate Algorithm (GCRA) [14] characterized by the two parameters T and , is standardized for exactly this purpose. Essentially the GCRA works like a leaky bucket, that is, credits are generated at a rate of 1=T such that a maximum proportional to can be present simultaneous. Each arriving cell needs a credit to be declared ....

ITU-T SG 13 Recommendation I. 371, Traffic Control and Congestion Control in B-ISDN.

....point so we get the buffer sizes (Q i ) as input parameters to our traffic control method. 2. 2 Traffic Control Parameters The main goal of traffic control is to protect the network and the user in order to achieve network performance objectives with optimum allocation of network resources [2]. To fulfill these objectives QoS requirements, traffic descriptors and network information needed for the generic traffic control functions. We have chosen the following parameters for our traffic control framework which is in agreement with the standardization work of ATM Forum [3, 4] and ITU T ....

....To fulfill these objectives QoS requirements, traffic descriptors and network information needed for the generic traffic control functions. We have chosen the following parameters for our traffic control framework which is in agreement with the standardization work of ATM Forum [3, 4] and ITU T [1, 2]: ffl Connection Traffic Descriptors: Peak Cell Rate (PCR) Cell Delay Variation Tolerance (CDVT) Sustainable Cell Rate (SCR) Maximum Burst Size (MBS) Minimum Cell Rate (MCR) and the conformance definition: the Generic Cell Rate Algorithm (GCRA) 2] ffl Quality of Service Parameters: Cell ....

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ITU-T Recommendations I.371 Traffic Control and Congestion Control in B-ISDN, Draft, December 1995.

....is to be executed real time, it should be simple and feasible by current technologies. 2 The Traffic Control Framework The general purpose of traffic control is to protect the network and the user in order to achieve network performance objectives with optimum allocation of network resources [14]. To fulfill these objectives QoS, traffic and network information are required for the generic traffic control functions. We have chosen the following parameters for our traffic control framework which is in agreement with the standardization work of ATM Forum [15, 16] and ITU T [13, 14] ffl ....

....resources [14] To fulfill these objectives QoS, traffic and network information are required for the generic traffic control functions. We have chosen the following parameters for our traffic control framework which is in agreement with the standardization work of ATM Forum [15, 16] and ITU T [13, 14]: ffl Connection Traffic Descriptors: Peak Cell Rate (PCR) Cell Delay Variation Tolerance (CDVT) Sustainable Cell Rate (SCR) Maximum Burst Size (MBS) Minimum Cell Rate (MCR) and the conformance definition: the Generic Cell Rate Algorithm (GCRA) 14] ffl Quality of Service Parameters: Cell ....

[Article contains additional citation context not shown here]

ITU-T Recommendation I.371, Traffic Control and Congestion Control in B-ISDN, Draft, December 1995.

.... definition for conformance testing as well as a feasible way to avoid compliant traffic sources from suffering from excessive cell discards in the UPC NPC mechanism due to the introduction of CDV it has been necessary to characterise the peak cell rate of an ATM connection by two parameters, see [14] and [1] ffl The peak emission interval T , which is the distance between two adjacent cells of the connection transmitted at peak rate. Equivalently 1=T is the peak cell rate of the connection. ffl The CDV tolerance . is the threshold value in a continuous state leaky bucket with leak rate ....

....large number of tandem queues with interfering traffic. 2 Conformance Testing (Modified 1 point CDV) and the G D 1 Queue We shall here give the definition of conformance without presenting the (non modified) 1 point CDV definition first. Readers interested in full details are referred to [13] [14] and section 2.2.1 in [8] Using the formalism given in I.356, an observed cell is conforming to the pair (T ; if and only if its (modified) 1 point CDV value y 0 k : c 0 k Gamma a k is smaller than the CDV tolerance . a k Blaabjerg, Moln ar, Methods for UPC dimensioning of a CDV ....

ITU-T SG 13 Recommendation I.371, Traffic Control and Congestion Control in B-ISDN.

....should approximately follow the demand. The large spectrum of traffic characteristics and QoS requirements has led to the definition of five ATM service categories (CBR, rt VBR, nrt VBR, ABR, UBR) by the ATM Forum (1996) which largely correspond to the transfer capabilities specified by the ITU (1996), and the discussion about new categories is still ongoing. The key areas of traffic management are connection admission control (CAC) usage parameter control (UPC) and priority control in the switching hardware, all of which have been extensively studied since many years (Krner, 1995) Quite ....

ITU-T (1996) Recommendation I.371: Traffic Control and Congestion Control in BISDN, International Telecommunication Union - Telecommunication Standardization Sector, Geneva.

....for the sessions. Max Min Fair Rate Control of ABR Connections S.P. Abraham 2 Our work, reported here, focuses on the fair allocation of resources available for ABR connections with nonzero MCR requirements. In the context of fair rate allocation with nonzero MCRs, ITU T s Recommendation I. 371 ([2]) has the following to say: The bandwidth available on an ABR connection is the sum of an MCR, which could be 0, and of a variable cell rate that results from sharing the available bandwidth among ABR connections via a defined allocation policy. A defined allocation policy means that the ....

ITU-T, "Traffic Control and Congestion Control in B-ISDN", Recommendation I.371, July 1995.

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ITU Recommendation I371, 1995. Traffic control and congestion control in B-ISDN. Geneva, Switzerland. 18

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ITU I.371, Traffic Control and Congestion Control in the BISDN.

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ITU I.371, Traffic Control and Congestion Control in the BISDN.

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ITU- Study Group 13, Draft Recommendation I.371, Traffic Control and Congestion Control in B-ISDN, March1994.

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ITU Recommendation I371 (1994). Traffic control and congestion control in B-ISDN. Geneva.

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