Signaling is crucial to the operation of modern telecommunication networks. A breakdown in the signaling infrastructure typically causes customer service failures, incurs revenue losses, and hampers the company image. Therefore, the signaling network has to be highest reliability and survivability. This in particular holds for the routers in such a network, called signaling transfer points (STPs).

In most cases, the signaling network is management independently from the transport network. Besides many other security facilities to ensure the capabilities of the network in failure situations, highest reliability is required from the central routing processors within the signaling network, the so-called signaling tranfer points (STPs). The robustness of an STP heavily depends on the distribution of the traffic load among the STPs individual processor units.

A STP is decomposed into clusters, which, in turn, consist of routing units and interface cards. In this paper, we denote the routing units as CCDs (for Common Channel Distributors) and the interface cards as CCLKs (for Common Channel Link Controllers). Every link has to be connected to some CCD via a CCLK. A CCLK has a certain capacity, which determines the number of links that can be attached. The CCLKs within a STP are numbered consecutively. Although CCLKs and CCDs in different clusters are connected through system-bus, a link should be connected to a CCD via a CCLK within the same cluster in order to keep the internal traffic in the failure free state as small as possible. Every link is contained in some linkset. All links in a linkset have the same origin and destination, and they are all routed via the same STP. To ensure the functionality of a STP in case of the breakdown of single CCDs or a cluster, the following restriction apply to the assignment of links to CCDs:

- A maximum of half the linksets may be connected to CCDs within the same cluster.

- The connections of a linkset have to be equally distributed among the CCLKs of even and odd parity.

- Links have to be connected to CCDs via a CCLK in the same cluster.