Functionality at the edge: designing scalable multiservice ATM networks

ATM offers the capability of consolidating multiple services onto a common backbone network, thereby reducing network management complexity, improving utilization, and lowering cost. As ATM networks grow, a virtual path connection (VPC) network core is often provisioned to reduce the number of connections to provide scalability for network management and performance. Provisioning a VPC network core raises a number of issues, especially related to the performance of bursty non-real-time connections. This article discusses these issues and how the functionality of ATM can best address them. It is shown that employing low-loss flow-controlled ABR VPCs to carry non-real-time traffic can provide significant gains in terms of performance as well as improved throughput for a given amount of buffering in the network core. The flow-controlled VPC enables the complexities of virtual channel connection- (VCC)-level congestion control, fairness, and isolation to be pushed to the network edge where lower speeds allow this functionality to be performed more cost effectively.