•  Auto adaption to line rate, interface and service type

Overview

The NMS 520 Series is General DataComm's premier family of network managed data service units (DSUs). It delivers the capabilities today's private line, digital networks need to remain agile and robust, from universal rate access and totally non-intrusive network management to three integral dial restoral choices— analog switched network, Switched 56 or ISDN. Distinguished by extensive line measurement functions, which allow precise assessment of circuit quality, the NMS 520 Series also provides a selection of powerful interface options. IBM networks, for example, will benefit from an LPDA-2 feature, while a synchronous/asynchronous data compression option can boost throughput by up to 6 to 1.

Legacy and LAN Applications

The NMS 520 Series can be used alone with the SpectraComm 5000 System, in pairs, or on secondary channel circuits with GDC's NMS 510 Series universal rate DSUs. It can operate not only in traditional point-to-point or multipoint applications with multiplexers and FEPs, but also in LAN environments with routers and servers. Equipped with the data compression option, the NMS 520 Series can be used to compress up to 384 Kbps of traffic for cost-effective transmission over 56 and 64 Kbps circuits. It also supports Link Problem Determination Aid (LPDA-2) diagnostics, providing compatibility with IBM 5822 series DSUs. LPDA-2-equipped NMS 520s can not only be mixed with 5822s on the same circuit, but also managed from IBM's NetView.

IFP or SNMP Management

When remote NMS 520s are combined with a central-site SpectraComm 5000 System, SNMP management under HP OpenView is achieved via the LAN-based SNMP Manager. As an alternative, limited management can be accomplished via an optional Intelligent Front Panel (IFP), a simple-to-use yet powerful tool for basic configuration, testing, optioning, and installation.

Integral Restoral

The NMS 520 Series supports highly flexible, integral dial restoral options including the DBU-89 for point-to-point dial backup via the PSTN, and the DBU-56FW for point-to-point/multipoint restoral via Switched 56 services. Point-to-point restoral via ISDN services is also possible using the NMS 520 IFP/ISDN and its Intelligent Front Panel. Restoral can be manual, using the DSM, SSC, or IFP, or automatic, upon loss of Data Carrier Detect (DCD) for a designated time. In automatic restoral, after a given number of calls to the first of up to 10 stored numbers, the next stored number is automatically dialed. After the primary circuit's DCD has been active for a specified time, the call is terminated, and data is automatically transferred back to the private line. The DCD-loss and DCD-active time periods are user programmable. In units with the DBU-56 FW or DBU-ISDN option, the maximum time in restoral mode can also be set. Security features when entering dial backup mode include password protection, dialer identification and a call-back feature.