An IP sub-network includes a gateway and a plurality of sub-network processors in communication with the gateway. An IP address is associated with each sub-network processor, the IP address having a sub-network address portion corresponding to the sub-network and a host address portion corresponding to the sub-network processor. Each sub-network processor generates a transaction identifier for each signaling message that is communicated by the gateway to the signaling network. The transaction identifier is based on the IP address and can be generated by separating the sub-network address portion of the IP address and concatenating the host address portion with a numerical value, which corresponds to a predetermined, non-random ordering scheme. A signaling message can be routed to a sub-network processor by concatenating the sub-network address portion with the host address portion used as part of the transaction identifier.