Integrating switching and facility networks

DETAILED DESCRIPTION The problems associated with prior solutions for implementing ATM or IP/MPLS in a large-scale network are overcome by providing an efficient means by which capacity in the network is more fully shared without adversely affecting call or session setup latency, and at the same time simplifying network operations.
This is achieved by performing the functions of route setup, route allocation, and capacity management in a network at the edges of the network.
By "edges" what is meant is the interface between an ATM switch or a IP/MPLS router of the network and another that is other than another ATM switch or IP/MPLS router of the network; for example, the interface between each ATM switch or IP/MPLS router and customers.
In accordance with the principles disclosed herein, the edges contain nodes that form the interface between the ATM switches and IP/MPLS routers and the link(s) that interconnect them and the outside world.
These nodes comprise controllers and other apparatus that in some cases may be incorporated in, or connected as adjuncts to, the ATM switches or IP/MPLS routers.
In an ATM network, edge nodes assign calls to virtual paths based on the destination of the call and the current load status of each of a number of preselected paths.
Thus, each call is assigned a VPI (Virtual Path Identifier) corresponding to the path chosen and a VCI (Virtual Circuit Identifier) corresponding to the identity of the call at that edge node.
The ATM backbone nodes route calls based solely on the VPI.
Destination based routing allows VPIs to be shared among routes from different sources to the same destination.
Capacity management and load balancing is achieved through a Fabric Network Interface (FNI) that is present in each of the edge nodes along with a Centralized FNI (CFNI), that maintains backbone link status.
In an ATM network, the FNI is responsible for keeping track of the load on each access link from its edge node to the backbone ATM switch it homes onto, as well as the load on each, backbone link of the calls it originated