ATM 网络中 ABR 业务的拥塞检测  

Congestion Detection of ABR Service in ATM Networks

作　　者：刘益林[1] 李建华[1] 顾尚杰[1] 诸鸿文[1] 

机构地区：[1]上海交通大学电子工程系

出　　处：《上海交通大学学报》1998年第8期16-20,共5页Journal of Shanghai Jiaotong University

摘　　要：在ＡＴＭ（异步转移模式）网络中，可用比特速率（ＡＢＲ）业务适用于数据传输服务．ＡＢＲ业务采用基于速率的闭环流量控制机制，交换机缓存的使用效率及排队队长与所采用的拥塞检测算法有密切的关系．在以往的讨论中，只是根据交换机缓存中排队信元的数量来检测有无拥塞的发生（数值门限方法），因而效率不高．文中介绍了一种新的拥塞检测方法：根据信元到达交换机的速率检测有无拥塞的发生，并以ＥＦＣＩ（显式前向拥塞提示）交换机为例，分析了这两种方法对缓存使用效率及信元发送速率的影响．计算机模拟的结果表明：采用这种新的算法，信元发送速率及缓存中信元队长的抖动更小，能够明显改善交换机缓存的使用效率，从而提高了ＡＢＲ业务的服务质量（ＱｏＳ）．ABR(Available Bit Rate) service is mainly used for data transmission in ATM(Asynchronous Transfer Mode) networks. ABR adopts ratebased, closed loop flow control mechanism. In ABR flow control mechanism, the buffer performance of ATM switch is deeply influenced by the adopted congestion control detection algorithm. The past analysis used the number of cells queued in the switch buffer to detect if there was a congestion occurred in the buffer(threshold method), so its efficiency was not high. In this paper, a new congestion control detection method——the ratebased method is proposed. The paper also analyzes the influence of the two methods to the buffer performance and cells' sending rate in EFCI(Explicit Forward Congestion Indication) switch. The computer simulation results show that the ratebased method greatly reduces the demand to buffer size, stabilizes the emitting rate of the sources, clearly improves the Quality of Service(QoS) of ABR traffic model.

关 键 词：异步转移模式 拥塞检测 ATM网络 ABR业务 

分 类 号：TN913.24[电子电信—通信与信息系统]