Operational Support Systems - A Brief History of OSS Architecture

A Brief History of OSS Architecture

A lot of the work on OSS has been centered on defining its architecture. Put simply, there are four key elements of OSS:

• Processes
  • the sequence of events
• Data
  • the information that is acted upon
• Applications
  • the components that implement processes to manage data
• Technology
  • how we implement the applications

During the 1990s, new OSS architecture definitions were done by the ITU-T in its TMN model. This established a 4-layer model of TMN applicable within an OSS:

• Business Management Level (BML)
• Service Management Level (SML)
• Network Management Level (NML)
• Element Management Level (EML)

(Note: a fifth level is mentioned at times being the elements themselves, though the standards speak of only four levels) This was a basis for later work. Network management was further defined by the ISO using the FCAPS model - Fault, Configuration, Accounting, Performance and Security. This basis was adopted by the ITU-T TMN standards as the Functional model for the technology base of the TMN standards M.3000 - M.3599 series. Although the FCAPS model was originally conceived and is applicable for an IT enterprise network, it was adopted for use in the public networks run by telecommunication service providers adhering to ITU-T TMN standards.

A big issue of network and service management is the ability to manage and control the network elements of the access and core networks. Historically, many efforts have been spent in standardization fora (ITU-T, 3GPP) in order to define standard protocol for network management, but with no success and practical results. On the other hand IETF SNMP protocol (Simple Network Management Protocol) has become the de facto standard for internet and telco management, at the EML-NML communication level.

From 2000 and beyond, with the growth of the new broadband and VoIP services, the management of home networks is also entering the scope of OSS and network management. DSL Forum TR-069 specification has defined the CPE WAN Management Protocol (CWMP), suitable for managing home networks devices and terminals at the EML-NML interface.