f a fault and, as a consequence, carry out rerouting through the network. The signaling network functions are broken down into two basic categories: Signaling message handling Signaling network management (see Section 14.4.1 for description) 14.7.2 Signaling Message-Handling Functions The signaling message-handling function ensures that a signaling message originated by a particular user part at an originating signaling point is delivered to the same user part 14.7 SIGNALING NETWORK FUNCTIONS AND MESSAGES (LAYER 3) at the destination point as indicated by the sending user part. Depending on the particular circumstances, the delivery may be made through a signaling link directly interconnecting the originating and destination points or via one or more intermediate signaling transfer points (STPs). The signaling message-handling functions are based on the label contained in the messages which explicitly identifies the destination and origination points. The label part used for signaling message handling by the MTP is called the routing label. As shown in Figure 14.3 (upper left portion), the signaling message-handling is divided up into the following: The message routing function, used at each signaling point to determine the outgoing signaling link on which a message is to be sent toward its destination point. The message discrimination function, used at a signaling point to determine whether or not a received message is destined to that point itself. When the signaling point has the transfer capability, and a message is not destined for it, that message is transferred to the message routing function. The message distribution function, used at each signaling point to deliver the received messages (destined to the point itself) to the appropriate user part. 14.7.2.1 Routing Label. The label contained in a signaling message and used by the relevant user part to identify a particular task to which the message refers (e.g., a telephone circuit) is also used by the message transfer part to route the message toward its 