Optical network management: back to basics


Before service providers consider any element and network management system (NMS) from an equipment vendor, they take a close look at the network elements (NEs). No matter how advanced the technology, service providers do not buy equipment that is difficult to manage on the floor.

While equipment vendors are concerned about product differentiation and innovation, they have to be careful not to take it too far. Network element operations are one area where conformity is better.

Take management interfaces as an example. In the transport world, TL-1 has long been the human and machine interface of choice and a great deal of OSS infrastructure had been built around it. Nevertheless, equipment vendors have implemented a series of machine interfaces such as the simple network management protocol (SNMP), common object request broker architecture (CORBA), and the common management information protocol/common management information service element (CMIP/CMISE).

Transport network equipment must have a standards-based TL-1 interface. Even if the network equipment is innovative to the point of being non-standard, TL-1 can still be used. Operator training time is limited to the new commands and (hopefully) the capabilities of the new equipment. That doesn't mean SNMP and CORBA don't have a place as management interfaces in optical networks (although we can probably wave good-bye to CMIP/CMISE). To maximise OSS interoperability and satisfy diverse worldwide customers, equipment vendors must support multiple interfaces.

Considering the changes in off-board management systems, trends in element management systems (EMSs) are closely tied to the network elements. As long as the NEs operate efficiently, the EMS' role is to automate tasks and streamline procedures. Some optical-networking equipment can support multiple speeds and protocols by collapsing functions into a single NE. Although these NEs are all conceived with the intent to save capex, only the NEs that do not require interface-card changes to run a different signal can reduce operating expenses.

Similarly, element management is a tool to unlock remote testing and diagnostic capabilities of the NEs to reduce both truck-rolls and service downtime. Equipment today must provide enough loopback capability to isolate failure — not only to a particular network element, but also to a specific card within an NE.

The EMS provides the capability to remotely set up, tear down loopbacks, and run diagnostics. It will even provide interpretation of results to streamline problem resolution. With operations focused on element management, new types of NEs are reducing opex for service providers by becoming easier to manage than their predecessors.

In recent years, while the large vendors were developing comprehensive integrated OSSs, many start-ups were taking the opposite approach. Their network management offering was limited to a "bare bones" element manager. However, the failure of these two opposing strategies has shown that service providers need something in between.

Optical networking systems vendors are now providing integrated element and network management solutions that allow the user to move seamlessly from a network to an element management view (see Fig.1).

For example, as optical networks evolve from ring to mesh or hybrids, visualising end-to-end connectivity is important for establishing service. An integrated system within a wavelength network gives the user the ability to view an end-to-end light path from a user console. The user can zoom in on the affected NEs. If there is a problem on a path, it is simple to locate. If there are maintenance activities planned on a fibre, the management system can quickly correlate a port, or fibre, to a list of network services.

Now more than ever, service providers want to install their own comprehensive end-to-end NMS. At first glance, this would appear to overlap with the notion of integrated element and network management from the equipment vendor. In fact, the two are completely complementary. All that is required is the concept of "management domains".

This concept divides the network management layer into a hierarchy of two levels. Above element management, domain managers provide network management functions, but only for their domain of control.

In this model, there might be a domain manager for the wavelength portion, the Ethernet portion, and the SDH portion of the network. Domain managers provide network-level visualisation, provisioning and monitoring for their domains. They also provide the conduit to the element management functions for the equipment in their domain (see Fig.2).

A major advantage is that the higher-level NMS has to be integrated with a relatively small number of domain managers rather than dozens of element managers.

Of course, this discussion would not be complete without a quick note on interface definitions and protocols to make this model work. The telecommunications industry has made numerous attempts to define standard interfaces to integrate OSSs. What had been lacking was the massive uptake of any particular standard.

That finally may be happening with the now predominant use of the Telemanagement Forum's TMF814 "Multi-technology Network Management Solution Set". This initiative describes a CORBA interface for management of SONET/SDH, DWDM and ATM networks. It has had sufficient uptake by the network equipment vendor community as a de facto standard. Given that de facto standards tend to breed followers and create barriers for adopting other interfaces, it ultimately means a single model for creating NMSs.

For years, the wrath of network operators has been directed at multivendor networks that require multiple management systems, multiple procedures, and ultimately the dreaded "swivel-chair management". The concept and deployment of domain management and the uptake of the Telemanagement Forum models are enormous steps toward eliminating these complex systems.

In the past, equipment providers built businesses around networking silos. Proprietary interfaces to management systems acted as a lock to keep customers tied to a single vendor. Service providers no longer tolerate this strategy. As a result, more and more equipment vendors — particularly smaller companies eager for their first sale — are opening up their management interfaces completely. The interfaces are based on industry standards that will enable the NEs to be rapidly integrated into OSSs.

In recent years, equipment vendors have come and gone from selling products in the service management area. They no longer have the means to develop and sell higher-level OSS systems. Over the same time period, the number of independent software vendors (ISVs) in this space has exploded, and more recently the number of ISVs has been reduced through consolidation and failure.

Equipment vendors have begun working more frequently with ISVs. While sometimes the relationships are as strong as an OEM agreement, more frequently the companies work together to pre-integrate the network equipment with the service management application. The result is that service providers can choose the best-of-breed application for their particular situation.

Despite moving out of the service management business, equipment vendors are still interested in seeing their equipment integrated as seamlessly as possible with the service provider's OSS. ISV partners and open management interfaces both play a role in enabling this.

Now, as an early part of the sales cycle, suppliers are engaging their service-provider customers to review operational strategies and the NMSs.

Nowhere is that more obvious than with the Telcordia-compliant OSS systems running in the RBOC networks. In the past, companies would try to avoid the OSMINE (operations systems modification for the integration of network elements) process; now they clearly understand that it is an absolute requirement.

For private companies, budgets are stretched to ensure that adequate funding is available for what may be an expensive process. At Telcordia's yearly network equipment provider symposium this year (a conference for those companies going through the OSMINE process), record attendance was reported. For an industry in decline, this attendance figure is an important indicator of the significance of OSMINE.

An economic downturn typically moves the power back to the purchaser. Due to intense competition, not only do costs come down but products also change for the better. Such is the current climate for service providers and their network equipment suppliers. New network management products will have a substantial impact on service providers' operations and their bottom line.

It is a perfect time for service providers to upgrade and evolve their OSS systems to take advantage of these capabilities. Perhaps the only frustrating aspect for service providers is that they have been preaching these sorts of requirements to the equipment vendors for years. Perhaps it just takes a harsh economy to make truly effective network management a reality.

Robert Gaudet is a director of product management for network management systems at Meriton Networks (Ottawa, Ontario, Canada). He can be reached via the company's web-site, www.meriton.com.

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