| 摘要 |
A dynamically controlled routing (DCR) telecommunications network is formed by a plurality of network switching elements, each connected to at least one other by at least one circuit group for carrying calls therebetween, and a network processor connected to the network elements by data links. Each network switching element determines, for each call, a neighbouring network element to which it should be routed. It does so by accessing a routing table which contains alternate routes to be attempted if a direct route either does not exist or cannot be used. The routing tables are updated periodically by the network controller. The DCR network functions as a group of nodes interconnected by links and routing takes place on a node-to-node basis. At least one of the nodes is a logical entity which does not necessarily have a direct correspondence to a single physical network element but rather corresponds to a group of at least one physical component which may be a network element, a part of a network element, or a plurality of network elements or parts thereof. Likewise, a link to the virtual node does not necessarily correspond to a circuit group but comprises the set of direct circuit groups connecting to the components of the virtual node. DCR networks employing virtual nodes have increased flexibility. For example, final destinations outside the DCR network can be associated with the virtual node as an intermediate destination node, thereby allowing a call to exit the DCR network via any of the components of the virtual node rather than via only one Unique Exit Gateway.
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