This paper addresses the problem of dimensioning multi-service ATM networks, where each service is supported by a different logical network. In the traditional approach, logical networks are configured with end-to-end VPCs, which greatly simplifies VCC admission control. This approach does not explore resource sharing gains since an end-to-end VPC bandwidth is assigned to each VCC flow. In this paper, we propose a 2-layer hierarchical VPC layout for the logical networks as an alternative approach to the end-to-end VPC layout. The 2-layer hierarchical layout divides the network into disjoint regions and each region has a special node, the border node, responsible for routing VCC flows to/from other regions. We present an integer programming model for the problem of dimensioning ATM networks with 2-layer hierarchical VPC layouts. The network dimensioning problem assigns the capacity and route of all VPCs and the appropriate border nodes as to achieve the least cost physical network. Our computational results show that for networks with 10 nodes, where resource sharing gains are low, substantial cost savings are obtained using 2-layer VPC layouts when compared with the traditional end-to-end VPC layout.