There is probably no topic in networking that is undergoing more radical change than the topic of service provider network management systems (NMS). Under the paradigms that prevailed before the 1980s, operations support systems (OSS) and network management systems tended to be unified. As packet networking emerged, it created a distinction between the management of the infrastructure (network management) and the management of the business of being a service provider (operations management). The demands of service providers to control operations costs have begun yet another shift -- back to a concept of unified management under a common framework.
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The standard framework for network management is defined both by the ITU, as the Telecommunications Management Network or TMN, and the TeleManagement Forum, as the Multi Technology Network Management, or MTNM, initiative. In both, the concept of network management embraces the control of the system of devices (of whatever type, from whatever vendor) that behave cooperatively to offer telecommunications services. Both models place the control of individual devices ("Element Management," meaning device management) below the NMS layer.
NMS systems approach the common problem of cooperative resource behavior in two very different ways. Equipment vendors and the ITU standards tend to take a bottom-up approach, viewing a service as being the product of network features. Thus, the key to creating and ensuring services is to control network behavior. This approach is also common among IP/Internet providers because these providers often support services created over a network rather than the creation of services on the network. The TMF and vendors that are active in service creation and management (DSL activation, etc.) view network management as a function exercised from above, playing a role in translating logical service descriptions into network actions.
The distinction here is far from academic. Top-down approaches tend to make service management the goal and network management the tool. This is suited to many of the emerging provider business models, but it collides with the current practices, which have typically evolved from a bottom-up approach and are now focused on the network operations center (NOC).
The primary mission of an NMS for most service providers is to support NOC activity; the support of service management systems' access to network resources is normally a second mission today but one that is likely to dominate in the future. The primary issues in NOC support are:
- Multi-vendor, multi-device access through a uniform interface. Most provider networks include many different devices from a variety of vendors, and learning the specific management interface to each combination is difficult. It is even more difficult to perform provisioning, commission new lines or nodes, or diagnose problems with different management interfaces. A common interface to all devices is mandatory for an effective NOC and is thus the first requirement for an NMS.
- Fault correlation and filtering. One of the major problems that providers face in the NOC is what are sometimes called "alert floods," which are masses of error messages created from a single failure of a key trunk or device that may affect thousands of other service elements. An NMS should provide both mechanisms to correlate such low-level, broad-impact failures with higher-level errors and the ability to suppress those messages in order to prevent operations personnel from being swamped in error messages.
- End-to-end provisioning and management. The purpose of "network management" is to manage cooperative behavior among devices, but there are relatively few products that actually provide that capability. Most equipment vendor NMS products work only with their own devices, and few products offer complete multi-vendor support. Australia's incumbent carrier, Telstra, selected Alcatel's Cross Domain Manager product for this multi-vendor, end-to-end support, even though the devices being managed were primarily from other vendors.
The NMS market, as previously noted, is increasingly turning toward a service management perspective, meaning that the customer care process may escalate a service problem to the NOC, and thus the NMS must have some mechanism for correlating services with network conditions. This problem is more significant than it may sound, particularly for IP services and other services created through end-to-end signaling (IP/MPLS, IP VPNs, for example) rather than by "management stitching." With such services, it is often difficult to determine what resources a service is actually using, and thus to correlate network and service conditions.
IBM, Cisco, Alcatel, Telcordia, and standards bodies such as the TMF are all working on the issue of creating effective links between service processes and NMS capabilities so that NOC personnel can drill down to uncover the network cause of service problems. All of these solutions are evolving, and NMS specialists will want to review the current state of the products available to determine which fits their requirements best at a given time. When making these assessments, keep in mind that vendor-proprietary approaches nearly always evolve faster than standards, but that such approaches may be more costly and may also fail to cover all of the devices and vendors that may eventually be used in a network.
About the author: Tom Nolle is president of CIMI Corporation, a strategic consulting firm specializing in telecommunications and data communications since 1982. He is a member of the IEEE, ACM and the IPsphere Forum, and publisher of Netwatcher, a journal in advanced telecommunications strategy issues. Tom is actively involved in LAN, MAN and WAN issues for both enterprises and service providers and also provides technical consultation to equipment vendors on standards, markets and emerging technologies.