TAILIEUCHUNG - Signaling System No.7 Protocol Architecture And Sevices part 59

MTP3: Management Messages These messages are generated by the MTP3 level to maintain the signaling service and to restore normal signaling conditions in the case of failure, either in signaling links or signaling points. MTP3 is explained in Chapter 7, "Message Transfer Part 3 (MTP3)." MTP3 messages carrying relevant information that can affect the network if abused and can be split into two categories | MTP3 Management Messages These messages are generated by the MTP3 level to maintain the signaling service and to restore normal signaling conditions in the case of failure either in signaling links or signaling points. MTP3 is explained in Chapter 7 Message Transfer Part 3 MTP3 . MTP3 messages carrying relevant information that can affect the network if abused and can be split into two categories Messages communicating unavailability such as COO COA ECO ECA TFP TFR and TFC Messages communicating availability such as CBD and TFA A higher degree of risk is associated with the first category because they diminish available resources. As such care should be given to the screening of such messages. For example the Transfer Restricted TFR message is involved in routing reconfiguration and traffic diversion. Therefore a degree of risk is involved in receiving or sending this message if it is propagated unintentionally or with malicious intent. Unintentional transmission is likely to be caused by software or configuration errors. Malicious intent is because someone with physical access an insider sends the message intentionally with the use of a protocol analyzer for example. Table 15-1 lists the main MTP3 messages that should be screened. Table 15-1. MTP3 Messages to Be Screened Message Parameter Reason for Screening MSU in case of an STP OPC Verifies that the originating node is known is present in the routing tables . This provides a degree of protection against unauthorized access to the network. DPC Verifies that the message is destined for a valid node a node to which the originating point is allowed to route . Changeover Changeback and OPC Verifies that the message is received from an adjacent node that is allowed to send this Emergency Changeover message type. DPC Verifies that the message is destined for itself. Transfer Prohibited Transfer Restricted OPC Verifies that the message is received from a node allowed to send these types of messages. Management .

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