An Introduction to the Ericsson Transport Network Architecture ...

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64 These functions and a number of other functions are described in greater detail and from the point of view of the SDH NEs in the section 'SDH Management'. Mode of operation The SDH NE can be managed from: - FMAS, the management system for the Transport Network - A Local Operator Terminal (LOT). The FMAS is necessary for the management of large transport networks. The LOT is required during installation, and can also be used to manage a single NE or a small transport network. All SDH NEs use a standardised interface to the FMAS. The protocols used are TMN (Telecommunications Management Network) Q3 interfaces as defined in CCITT Recs. Q.811 and Q.812, Box 2. All SDH NEs also use a common Information Model (IM). The IM defines the syntax Fig. A Gateway Network Elements (GNE) may be connected to an OS. The GNE has an attached subnetwork of SDH NEs BOX 2 Q3-lnterface The Q3 interface provides for standardised communication and exchange of management information between an NE and an Operations System. The protocol suite and the information model must be defined when specifying a Q3 interface. Gateway Network Element (GNE) A GNE is connected to an OS via a Q3 interface, Fig A. The GNE has an attached subnetwork of SDH NEs and provides remote access to these NEs by means of Embedded Control Channels (ECC). The GNE performs Intermediate System (IS) network layer routing functions for ECC messages destined to any NE within the subnetwork. When considering implementation, there is no difference between a GNE and any other SDH NE. They simply perform different roles in the OSI environment. Embedded Control Channel (ECC) The ECCs provide a high-capacity data communication network between SDH NEs, utilising dedicated bytes (DCC) in the STM-N Section Overhead as the physical layer. Two types of ECC have been defined in the SDH standards: -ECCr A192 kbit/sdata communications channel accessible by all NEs, including the intermediate regenerators -ECCm A 576 kbit/s data communications channel accessible by all NEs, excluding the intermediate regenerators The ECC network is logically created by defining ECC network routes in the SDH transport network. Network Protocol Data Units (NPDU) are then routed according to address and routing information held locally in the NEs as routing tables, or terminated within the NE. Table 1 SDH GNE Local Routing Table NPDU Destination Address "SDH NE" "OS" "SDH GNE" Next Hop (SNPA) "STM-N ECC" "Q3" "Own Agent" In the absence of standards, a set of Ericsson proprietary DCN management functions has been defined for the purpose of managing the routing tables and DCN resources. ERICSSON REVIEW No. 3, 1992
65 of the messages that are sent between the SDH NEs and the FMAS. SDH Management General SDH Management is based on TMN and OSI principles to allow for the building of an open network architecture. The basic concept behind TMN is to provide an organised architecture to achieve interconnection between various types of Operations System (OS) and/or telecommunications equipment for the exchange of management information, using standardised protocols and interfaces. From a management point of view, the SDH NE can be considered from three different perspectives: - A functional perspective - An information model perspective - A data communication perspective, each of these perspectives defining some of the aspects necessary for standardised multi-vendor operations. Functional Perspective The Functional perspective defines the management services that a single SDH NE can provide to a local operator, or to a network management system. In the TMN context, these functions are referred to as TMN management functions. The TMN management functions belong to different management functional areas. Those relevant for SDH NEs are: Configuration Management, Fault Management, Performance Management and Security Management. In addition, a set of Data Communication Network management functions dealing with configuration of data communication resources have been defined. Within ETNA, the SDH NE-related services are used by the FMAS to provide network-related services such as trail provisioning, protection routing, path performance monitoring, etc. Some examples of the most important TMN management functions provided are summarised below. Configuration Management (CM) Compared with traditional transmission equipment, the SDH NEs also include a switch which provides for the set-up of broadband semi-permanent connections. The main CM task is to control this switch, but CM also controls other aspects of the configuration of the NE: - Termination Point Provisioning The different types of termination point, i.e. physical interfaces, trail termination points and connection termination points, can be configured in different ways, e.g. assigned identities, alarm thresholds, enabling and disabling of the laser, etc. The termination points are automatically created when the related printed board assemblies are inserted - Equipment Configuration The SDH NEs are in many ways selfconfigurable after installation or extension of the hardware, e.g. when new access ports are installed. The equipment configuration functions keep track of the equipment currently installed, e.g. printed board assemblies and software, and report to the OS if changes have been made - Cross-Connect The cross-connect functions set up connections through the switch and keep an up-to-date list of the crossconnections currently being ordered - Protection Switching The SDH NEs can be configured to perform different types of autonomous protection switching (fast restoration) of paths or sections to dedicated standby network resources following a network failure - Synchronisation Configuration Each NE must be synchronised from a valid synchronisation source, e.g. a 2 Mbit/s signal, a 2 MHz reference or an STM-N signal. The synchronisation source configuration functions define the synchronisation source to be used, and what actions should be taken when the primary source fails - NE-Recovery The SDH NEs contain a lot of data which must be administered, e.g. regularly backed up. During certain trouble conditions it may also be necessary to perform restarts at different levels. Fault Management (FM) Fault management provides functions for detection, isolation and correction of abnormal states in the network. This includes both network-related faults, resulting from cable breaks or deteriorating line systems, and abnormal conditions within the NEs themselves. The main FM task is to report ERICSSON REVIEW No. 3, 1992
Page 1: ERICSSON REVIEW 3 1992 An Introduct
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Page 20 and 21: 74 Functional requirements Certain
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Page 32 and 33: 86 The control signals, which come
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