1. Field of the Invention
The invention is related to the field of communications, and in particular, to communication network architectures and services.
2. Description of the Prior Art
Time division multiplex (TDM) networks may be flat networks. In a flat network each switch or device is connected to every other switch or device. FIG. 1 is a block diagram of a typical flat TDM network. When a connection needs to be made from one switch to another switch there is always a direct connection between the two switches. For example when switch 102 needs to connect to switch 106, the connection is made using trunk 110. Sometimes the direct trunk between switches becomes congested by heavy traffic. Dynamic call routing (DCR) is one method that helps overcome congestion problems. A system using DCR monitors the conditions along the trunks. When a path between two switches has a problem, for example heavy congestion or a trunk failure, the system will use an alternate trunk for the connection. For example, when trunk 110, between switches 102 and 106, has a problem, the system may establish the connection from switch 102 to switch 108 along trunk 112, and then from switch 108 to switch 106 along trunk 114. In this way the connection between switch 102 and 106 is completed without using the trunk with the problem. HDC systems typically monitor the CPU occupancy of a switch or the trunk or link occupancy to track usage at a switch or through a trunk.
Packet based networks don't typically have dedicated links between each network device (i.e. the network is not flat). Packet based networks typically create virtual paths or virtual connections between two IP addresses. A virtual path typically can be created between two network devices in the packet based network even when there may not be a direct physical link between the two network devices. Sometimes the link or connection between two IP addresses are called tunnels, they can also be called routes. Packet based networks use a similar technique to route traffic around congestion or failures in the network structure. Packet based networks may track usage along a virtual connection by counting the number of hops packets take to reach the destination, they may track latency, or they may track percent bandwidth used at the router or port level. Many TDM networks are now connected to packet based networks. Unfortunately there is no sharing of the path conditions between a TDM network and a packet based network.
Therefore there is a need for a hybrid dynamic connection routing system to share routing information between the two types of networks.