This paper discusses the characteristics of TCP when it employs ABR and UBR seduces , and the influence of the ATM switch buffer on the Performance of TCP .
Secondly , the mathematical modeling of the heterogeneous traffic ( such as , CBR VBR ABR and UBR ) and discrete event system simulation which is used in this paper are discussed ;
Simulation results show that the TCP performance of ABR service is better than that of UBR service in terms of buffer requirement , fairness of bandwith allocation , throughput , and link utilization .
ABR ( Availble Bit Rate ) and UBR ( Unspecified Bit Rate ) are new service in the ATM ( Asynchronous Transfer Mode ) network , which are mainly used for data communication .
Entities in a private registry , for instance , can now be copied into another affiliated private registry for broader exposure or into a root registry , such as the UBR , for public consumption .
This paper reviews the main research areas of TCP over ABR and UBR , describes the current status , points out the key problems , and makes a comparison between TCP performances under two transport modes .