Explicit Rate Indication For Congestion Avoidance Research Articles

자기 유사한 트래픽을 이용한 ATM 스위치의 ABR 혼잡제어 알고리즘의 성능분석

네트워크를 설계하고 서비스를 구현하는데 있어서 중요한 변수중의 하나는 트래픽의 특성을 파악하는 것이나 기존의 트래픽 예측과 분석은 포아송(Poisson) 또는 마코비안(Markovian)을 기본으로 하는 모델을 사용하였다. LAN, WAN 및 VBR(Variable Bit Rate) 트래픽 특성에 관한 최근의 실험적 연구들은 기존의 포아송 가정에 의한 모델들이 네트워크 트래픽의 장기간 의존성 및 자기 유사한 특성들을 과소평가 함으로써 실제 트래픽의 특성을 제대로 나타낼 수 없다는 것을 지적해 왔고 최근 실제 트래픽과 유사한 모델로서 자기 유사한 특성을 이용한 접근법이 대두되고 있다. 따라서, 본 논문에서는 실제 트래픽과 유사한 자기 유사 데이터 트래픽을 백그라운드 부하로 발생시켜 기존의 ABR (Available Bit Rate) 혼잡제어 알고리즘 중 대표적인 EFCI(Explicit Forward Congestion Indication), EPRCA(Enhanced Proportional Rate Control Algorithm), ERICA(Explicit Rate Indication for Congestion Avoidance), NIST(National Institute of Standards and Technology) 스위치 알고리즘이 버스트한 트래픽에 대해 효율적으로 반응하는지를 ACR(Allowed Cell Rate), 버퍼 사용율, 셀 폐기율, 전송효율 등으로 나누어 분석을 하였다. One of the most important matters in designing network and realizing service, is to grip on the traffic characteristics. Conventional traffic prediction and analysis used the models which based on the Poisson or Markovian. Recently, experimental research on the LAN, WAN and VBR traffic properties have been pointed rut that they weren't able to display actual real traffic specificities because the models based on the Poisson assumption had been underestimated the long range dependency of network traffic and self-similar peculiarities, it has been lately presented that the new approach method using self-similarity characteristics as similar as the real traffic models. Therefore, in this paper, we generated self-similar data traffic like real traffic as background load. On the existing ABR congestion control algorithm, we analyzed by classify into ACR, buffer utilization. cell drop rate, transmission throughput with the representative EFCI, ERICA, EPRCA and NIST twitch algorithm to show the efficient reaction about the burst traffic.

Comparative study of two flow control mechanisms in high speed networks

Considerable protocol development efforts in recent ATM (Asynchronous Transfer Mode) Forum activities have been focused on the traffic management of available bit rate (ABR) service. It has been shown that ABR service enables persistent, greedy data sources to efficiently utilize ATM network resources with the help of a rate-based flow control mechanism. ATM Forum Traffic Management Specification Version 4.0 document gives a complete description of the end system behavior of the flow control mechanism, but it leaves the details of the switch behavior to be vendor-implementation dependent. For the sake of compatibility and interoperation among flow control mechanisms implemented by vendors, two rate-based mechanisms EPRCA (Enhanced Proportional Rate Control Algorithm) and ERICA (Explicit Rate Indication for Congestion Avoidance) have been recommended in the specification. In this paper, the mechanisms are studied and their performance is analyzed and compared with a material network. Simulation shows that ERICA is significantly better than EPRCA in the performance of steady state and instantaneous state of source end system ACR (Allowed Cell Rate) and buffer queue of bottleneck switch.

Interoperability of EFCI and ERICA ATM switches for ABR services with VS/VD enhancements

To improve network bandwidth utilization, the asynchronous transfer mode (ATM) forum has standardized available bit rate (ABR) service which requires a number of parameters to be negotiated during connection setup. MCR is the minimum cell rate guaranteed by the network and can be used to provide an acceptable quality of service for applications. In this study, explicit forward congestion indication (EFCI) and explicit rate indication for congestion avoidance (ERICA) switches were adopted in a current transitional ATM network. First, we transfer traffic with ABR service to realize the interoperability of EFCI and ERICA switches. Second, we implemented the virtual source/virtual destination (VS/VD) feature into a homo or heterogeneous EFCI and ERICA switch environment in order to observe the performance. From the simulation results, a smaller queue length was obtained after the VS/VD was introduced into the EFCI and ERICA switches. The high link data transfer utilization with ABR service was also obtained.

Optimal structured feedback policies for ABR flow control using two-timescale SPSA

Optimal structured feedback control policies for rate-based flow control of available bit rate service in asynchronous transfer mode networks are obtained in the presence of information and propagation delays, using a numerically efficient two-timescale simultaneous perturbation stochastic approximation (SPSA) algorithm. Models comprising both a single bottleneck node and a network with multiple bottleneck nodes are considered. A convergence analysis of the algorithm is presented. Numerical experiments demonstrate fast convergence even in the presence of significant delays. We also illustrate performance comparisons with the well-known explicit rate indication for congestion avoidance (ERICA) algorithm and describe another algorithm (based on ERICA) that does not require estimating available bandwidth (as in ERICA).

Quality of service-oriented protocols for resource management in packet-switched satellites

The present paper deals with bandwidth allocation and congestion avoidance in a broadband satellite with on-board switching, oriented towards guaranteeing the Quality of Service (QoS) associated with various traffic/service classes as defined by ATM forum. At the core of the bandwidth allocation a novel uplink (UL) access protocol is proposed, based on a Multi-Frequency Time Division Multiple Access (MF-TDMA) primary access scheme, in conjunction with a downlink (DL) access protocol based on a more traditional Time Division Multiplex (TDM) scheme. This UL access protocol is complemented by a rate-based congestion control protocol (consistent with ATM Forum recommendations), which is an adaptation to GEO satellites environment of the Explicit Rate Indication for Congestion Avoidance (ERICA) algorithm developed for terrestrial networks. The performance of both UL access and congestion avoidance schemes has been evaluated through extensive simulations and the results compared with those obtained with other protocols or by analytical approximations.