Signaling System No.7 Protocol Architecture And Sevices part 19

Signaling Network Management Failures in the SS7 network have potentially devastating effects on the communications infrastructure. The loss of all SS7 signaling capabilities at an SP isolates it from the rest of the network.
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Signaling System No.7 Protocol Architecture And Sevices part 19Signaling Network ManagementFailures in the SS7 network have potentially devastating effects on thecommunications infrastructure. The loss of all SS7 signaling capabilities at an SPisolates it from the rest of the network. The SS7 networks in existence today areknown for their reliability, primarily due to the robustness of the SS7 protocol inthe area of network management. Of course, this reliability must be accompaniedby good network design to provide sufficient network capacity and redundancy.MTP3 Network Management is comprised of a set of messages and proceduresthat are used to ensure a healthy signaling transport infrastructure. This involvesautomatically invoking actions based on network events, such as link or routefailures and reporting network status to other nodes.Signaling Network Management is divided into three processes: • Traffic management • Route management • Link managementTraffic management is responsible for dealing with signaling traffic, which are themessages generated by MTP3 users, such as ISUP and SCCP. The goal of Trafficmanagement is to keep traffic moving toward its destination, even in the event ofnetwork failures and congestion, with as little message loss or mis-sequencing aspossible. This movement often involves rerouting traffic onto an alternate networkpath and, in some situations, might require message retransmission.Route management exchanges information about routing status between nodes. Asevents occur that affect route availability, route management sends messages tonotify other nodes about the change in routing states. Route management suppliesinformation to traffic management, allowing it to adjust traffic patterns and flowaccordingly.Link management activates, deactivates, and restores signaling links. This involvesnotifying MTP users of the availability of signaling links and invoking proceduresto restore service when a disruption has occurred. This level of networkmanagement is most closely associated with the physical hardware.A number of timers are involved in all of these network management procedures.Timers are used to ensure that actions occur when they should. Without timers,network management procedures could halt at certain points and it would takeforever for an event to happen. For example, when a message is transmitted, timersare often started to ensure that a response is received within a specified period oftime.The following section discusses a number of the timers used for Signaling NetworkManagement. It enhances the description of the procedure but is not intended to bea complete reference for every timer used. A complete list of timers can be foundin Appendix G, MTP Timers in ITU-T/ETSI/ANSI Applications.Network Management Messages (H0/H1 Codes)All network management messages contain a routing label and an identifier knownas an H0/H1 code. Additional message fields are often included based on theparticular message type. The general format of a Network Management message isshown in Figure 7-15. Figure 7-15. Basic Network Management MessageThe H0/H1 codes, or Heading codes, are simply the message type identifiers.There are two Heading Codes for each message: H0 for the family of messages,and H1 for the specific message type within the family. Table 7-4 lists the H0/H1codes for each message type. The family (H0 code) is listed on the left of the chart.All messages in a row belong to the same message family. For example, the H0/H1code for a COA message is 12 and it belongs to the CHM (Changeover Message)family. Appendix A, MTP Messages (ANSI/ETSI/ITU), provides the fullmessage name and description for each message entry in Table 7-4. Table 7-4. H0/H1 Codes H 0 1 2 3 4 5 6 7 8 1Message HGroup 0 0Changeov 1 COO COA CB CBAer (CHM) DEmergenc 2 ECO ECAyChangeover (ECM)Flow 3 RCT TFCControl(FCM|Transfer 4 TFP TCP[* TFR TCR[ TF TCA[ ] *] *](TFM) ARouteset 5 RST RSR RCP[ RCR[ *] *]Test(RSM) RSP[*]Manageme 6 LIN LUN LIA LUA LID LFU LLT/LLI LRT/LRI [*] [*]ntInhibiting(MIM)Traffic 7 TWR TRW[ *](TRM) AData Link 8 DLC CSS CNS CNP(DLM) 9User Part A UPUFlowControl(UFC)[*] ANSI only.Link ManagementLinks are physical entities that are made available to MTP3 users when they ...