n CTD Unspecified Unspecified Specified Specified Unspecified Unspecified Unspecified Mean Time between Outage The service mean time between outage (MTBO) is defined as the average duration of a time interval during which the portion is available from the service perspective. Consecutive intervals of available time during which the user attempts to transmit cells are concatenated. The network MTBO is defined as the average duration of a continuous time interval during which the portion is available from the network perspective. The service class related parameters are given in Table 3.8. ATM Addressing Like IP, the ATM has a scheme by which the ATM end points, such as end nodes, can be given a unique address. The address can be public and private, of which the former are defined by the ATM Forum while the latter are defined by ITU-T. Public addresses are based on the telephone networks (E.164) while the private addresses are based on the International Organisation for Standardisation (ISO) network service access point (NSAP) format. E.164 basically consists of country code (CC), national destination code (NDC) and the subscriber number (SN): E.164 = CC + NDC + SN The country code (CC) identifies the country where the subscriber is while the national destination code identifies how the country is divided into ISDN networks. The subscriber number identifies the subscriber (end user). Though the international number may be of variable length, the maximum international number length is 15 digits. A private address, also called an ATM end system address (AESA), is always of 20-octet length and is composed of an initial domain part (IDP) and a domain specific part (DSP). The IDP consists of the authority and format identifier (AFI) and the general domain idex (IDI). The DSP is subdivided into the high order DSP (HO-DSP), the end system identifier (ESI) and the selector (SEL): AESA = IDP + DSP = (AFI + IDI) + (HO - DSP + ESI + SEL) The AFI describes the type of the address (DCC (Data Country Code), ICD (International Co