Core Versus Edge
WAE Design plan files allow nodes to be defined as either core nodes or edge nodes. Note that these definitions are not related to any explicit router configurations. A similar classification of circuits is determined implicitly by the nodes they connect. If a circuit is attached to one or more edge nodes, it is defined as an edge circuit. Otherwise, it is a core circuit. Edge metrics and core metrics mean metrics of edge or core circuits, respectively.
This core and edge distinction helps define certain policies followed by WAE Design tools. In Metric Optimization, these are as follows:
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Only core metrics are changed.
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The objective is to minimize utilization in the core. Utilization in the edge is not taken into account.
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The routes selected by the metrics are restricted by the tool so that any route between a source and a destination will enter the core at most once, and leave the core at most once. That is, edge leakage of routes is prevented.
A consequence of these policies is that larger edge metrics in the plan file to be optimized might result in better optimized core routes. With larger given edge metrics, the Metric Optimization tool has more flexibility in how it can set the core metrics without leakage of routes into the edge.