Within a managed system we tend to define two geographic terms identifying the direction to which we are referring. The term south-bound (as in south-bound interface [SBI]) is used to define the reference from the operator’s network looking towards the subscriber’s equipment. The term north-bound interface (NBI) is used to define the reference from the subscriber’s equipment looking towards the operator’s management network. Within a given managed entity of a management system (network management system or element management system), both south-bound and north-bound interfaces are “managed” through a series of protocols. Over the years these protocols have transitioned from “back-in-the-day” archaic protocols such as TL-1 to modern-day protocols such as XML and SOAP.

Within the ISO framework, fault management is responsible for detecting, correlating, and providing the necessary interfaces for correcting a failure within the managed devices. A failure may be defined as an event within the network causing the system to operate outside its normal operating conditions. The failure may be defined as transient or persistent, requiring the management system to have the capacity to detect either condition under all operating environments.

If there was a component of the overall system architecture which could be considered critical to the success of the entire system at all times then we would have to say that accounting management is that component. Accounting management provides far more than just visibility and processing of revenue streams within the system. Below is a listing of components which may be incorporated into the accounting management system. Depending upon the service models deployed some of these may not be necessary or you may include additional over time.

The primary goal of configuration management is simple enough: provide the tools necessary to enable and disable services as required to ensure smooth routine operation of the system. One of the key tasks for which configuration management is responsible is taking those marketed network services and mapping them into the various managed objects within the active equipment. In other words, configuration management provides the key interface for enabling and disabling network services.

Network operators are faced with challenges when it comes to understanding those possible artifacts which may cause a decrease in performance experienced by subscribers. When a network is architected, the operator must make decisions on how the service provisioned will be “oversubscribed.” What this means is that an operator must make a capital decision on how much capacity will be available to all subscribers within the network compared to how much bandwidth is “offered” or “provisioned.” The concept of oversubscription has been around for generations, even well outside of the telecommunications world. For example, when a road is to be built a decision has to be made on how many lanes need to be provided, and in Atlanta, GA, with all the traffic there is never enough. However, it would not be prudent of the local governing authority to build a road such that there is never congestion. The governing authority just needs to continually monitor the situation such that if the situation becomes overbearing then the road must be expanded or new roads constructed. Planning is crucial because construction work takes time and taking too much time could present a series of other challenges and delays in completing the road.

The final functional area should not be considered the least important. Security management is just as important as each of the other functional areas. Without a strong security policy set forth within a management system all other aspects of the system will be compromised. Over the past two decades more and more of peoples’ lives have become digitalized. As much as we would like to hope that everyone is good out in the Internet, as my mother used to say, “if there is a mud puddle in the yard, I was going to find it and make a mess of things regardless.”

Connectivity fault management (CFM) as defined in IEEE802.1ag is an end-to-end per-service-instance Ethernet layer operation, administration, and management (OAM) protocol. It includes proactive connectivity monitoring, fault verification, and fault isolation for large Ethernet metropolitan-area networks (MANs) and wide-area networks (WANs). ITU-T Y.1731 defines similar functionalities and adds performance management. In comparison, IEEE802.3ah (the original EPON standard, now subsumed into 802.3) EFM only defines link-layer fault management.

OTDR (optical time domain reflectometry) provides a very convenient way to troubleshoot problems in the fiber plant itself. It gives you a picture of how the light propagates through the fiber, and can show splices, connectors, splitters, and breaks or other fiber faults. You will find that an OTDR is your best physical-layer troubleshooting tool. A typical PON OTDR trace will look like the one in Fig. 14.11. A simple single-stage splitter is in the ODN.

ITU G.984.1 [Gigabit-capable passive optical networks (GPON): General Characteristics. 03/2008] defines four types of protection. These can be used to protect high-value customers from physical layer faults and some electronic faults, at the expense of extra equipment and fiber routing. The most common two types that FTTH vendors have implemented are type B and type C. Protection is only defined for GPON and may or may not have been implemented by a given manufacturer, and certain EPON manufacturers may have implemented their own protection, which may or may not work as shown below.