【正文】 The NSC maintenance and management。 The No. 7 signalling work incident reports and the corresponding malfunction alarm。 M), between it and the HSTP adopt the No. 7 link and x. 25 link connection, No. 7 news management link is used to pass SP points. C1 and C2 longdistance bureau through the No. 7 signaling links are connected to the NSC, system mainly plete: the No. 7 signalling work work structure graphics display。s request, provides the reliable method, make the signal transmitted in the correct order and not be lost or repeat. NO. 7 signalling system USES highspeed data link (64 kbit/s) transmit signal, signaling links is a bidirectional path of sending signaling messages between signaling points, by the data link and data link terminal at the ends of the circuit to plete the NO. 7 signalling system function structure of the secondary function. NO. 7 signaling data link with transmission speed, call setup time is short, large capacity, signal changes with flexible expansion, signaling equipment investment, high utilization rate of speech path, etc. In No. 7 signalling system in SPC exchange, we can enjoy a variety of service functions, including the Lord called number recognition, busy callback, call waiting, don39。 IP total bandwidth is 100 m, according to the established MTP1 layer on the platform of CPCI EPI plate processing, in 32 platforms is DTM plate processing. MTP1 layer as we build a initial highway, without installing any traffic lights, did not indicate which road. 2). MTP2 signaling link layer: corresponds to the data link layer of the OSI model. Signaling links function mainly stipulated in two connected directly transmit signaling messages between signaling points provide reliable signaling links the required functionality. MTP2 layer of the main features are: signal units to send and receive control and signaling link state monitoring. Signal units to send and receive control mainly includes: signal units, signal units of positioning, and separating signal units of error detection and error correction signal units. While signaling link state monitoring mainly includes: signal unit error rate monitoring, processor debugging and signaling links troubleshooting of flow control and congestion. MTP2 layer simply put it to the upper provides a reliable logical channel, as to the content of the signaling messages do not make any processing, only the message stream in insert positioning delimiter, and error check digit. The insert positioning delimiter, and error check digit is transparent to the upper user, so we can say MTP2 layer of signaling messages do not do any processing. MTP2 layer on the platform of CPCI CPC gusset plate processing, in 32 platforms is LAP board processing. MTP2 layer like a installed the traffic light highway, the traffic on the roads have break even and smooth. But there is no marked this road goes. In MTP2 layer there are: the concept of the link, link state (activation, to live), SLC, SLCS and link number, link category (TDM64K TDM2M MTP3BLNK, M3UALNK), link level of flow control. 3). MTP3 work layer: this layer with SCCP layer corresponds to the OSI work layer. MTP2 layer ensures the two connected directly to the reliability of the signaling messages are transmitted between signaling points, but it for signaling messages do not make any processing (from the user level, actually MTP2 layer can insert into the message stream positioning delimiter and error check digit), MTP3 is dealing with the lowest layer of the signaling message. On the basis of the MTP2 layer MTP3 layer implements the function of the signaling work level that have the function of the routing address. MTP3 layer provides the signalling work routing addressing the function, the signaling message sending and receiving all play an important role in the process. MTP3 layer has two main functions: the signaling message handling and signaling work management. Signaling message handling internal and can be divided into three areas: message identification, distribution of the message and make up the road. Signaling work management can be divided into: signaling business management, and signaling routing management, signaling links. According to the above description we can clearly know the basic function of the MTP3. MTP3 layer like a installed traffic lights, also marked the whereabouts of highway. The traffic on the highway not only have broken even and smooth state, but also the function of the routing addressing. 4). SCCP signaling connection control layer and layer MTP3 together corresponds to the work layer of the OSI model. Signaling connection control part is the purpose of strengthening the function of the message transfer part (MTP), which together with the MTP3 constitute NO. 7 signalling work layer, for signal transmission in the work39。 There are two kinds of TDM speed, a 64 k (E1 line in a certain time slot), another is 2 m (using E1 line 31 slots)。 Their are quite different in the bearing layer, but the different is transparent to the upper user. TDM and ATM we called narrowband transmission and IP we called broadband transmission。s NO. 7 signalling work is three layer architecture, adopts double plane structure. Three layer structure are: senior signalling HSTP (distributed in all major provinces), lowlevel signalling LSTP (distribution in the prefecture level), signaling point SP (also known as end bureau, general distribution in the regional county)。 IP total bandwidth is 100 m, according to its several different conditions, the bandwidth also different accordingly. Three kinds of load mode of hierarchical structure is as follows: the following will be detailed in NO. 7 signaling hierarchy, as well as the role of each layer. NO. 7 signaling hierarchical structure diagram is as follows: we mainly use HLR system NO. 7 si