Operation Manual – Routing ProtocolH3C S9500 Series Routing Switches Chapter 5 Integrated IS-IS Configuration5-45.1.3 NSAP Structure of IS-IS Routing ProtocolI. Address structureAFI IDI High Order DSP SyStem ID SEL(1 octet)DSPIDPArea AddressFigure 5-2 NSAP structureOSI adopts the address structure as shown in Figure 5-2. NSAP includes initial domainpart (IDP) and domain specific part (DSP). The IDP is defined by ISO; it consists ofauthority responsible for assigning the rest of the address and address format. TheDSP is allocated by the authority specified in IDP. IDP and DSP are length-variable witha total length of 20 bytes.z Area AddressIDP includes authority and format identifier (AFI) and initial domain identifier (IDI). AFIdefines the format of IDI. DSP has several bytes. The combination of IDP and HO-DSPcan identify a route area and an area of the route area, so the combination is called anarea address.In general, you only need to configure an area address for a router. The area addressesof all nodes are the same in an area. To support the seamless combination,segmentation and conversion, S9500 series support up to three area addresses.z System IDSystem ID uniquely identifies terminal system or router in a route area. You can selectlength for it. For S9500 series, System ID length is 48 bits (6 bytes). In general, you canobtain System ID according to Router_ID.If the IP address 168.10.1.1 of the interface LoopBack0 serves as a router_ID for therouter, you can use the following method to obtain the System ID:Turn each part of the IP address 168.10.1.1 into three digits. Add 0 to the front of thepart less than three digits.Divide the expanded address 168.010.001.001 into three parts. Each part contains fourdigits.You get the System ID 1680.1000.1001.
