Mar 272010

Inventory managers keep track of all items in the infrastructure. They give us a complete view of our network in an end-to-end perspective. Having a complete, up-to-date inventory brings several benefits such as;

• Lower CAPEX and OPEX (by utilizing all of the equipment/links available at full capacity, by enabling full automation)
• Increase customer satisfaction (by reducing the provisioning times)
• Shorter time to market for new services (by managing the complete lifecycle)

Inventory items fall in different categories. Resource inventory, for example, deals with resources while service inventory keeps track of services and their relationships with resources. There is also product inventory (generally called product catalog) which keeps records of products that are sold to the market. Today’s inventory management platforms are able to keep all types of inventory. But traditionally when we talk about the inventory management (called NIM-network inventory management sometimes) we generally tend to mean the Resource Inventory.

Resource Inventory comes in two types: Physical and Logical.

Physical Inventory denotes physical items in our infrastructure such as Cabinets, racks, cards, ports, slots. Locations (cities, sites, buildings, rooms) are also in this category.

Logical Inventory is the inventory that keeps track of intangible entities that are provisioned on physical resources. Circuits, IP address ranges all are examples to logical inventory items. Logical inventory is related with Level 2 and above in the OSI structure.

Inventory items can be entered manually or imported to the system. The items that are not “managed” by element managers (such as cabinets) are the candidates for manual entries. (Most tools also give you the option to import from spreadsheets).

Managed elements should be imported from their EMS systems, via their northbound interfaces (NBIs). There are several protocols that different EMS implementations use. Inventory Management systems use specific adapters to collect inventory data from specific EMS systems.
After the full inventory is received from the EMS systems, this data should be kept up-to-date. The deltas appeared in the EMS inventory data are applied to the inventory manager by a resynchronization process.

Most of the times, import of the inventory data is challenging. We have to cope with different types of data, in different names, exposed with different types of NBIs. The naming convention, for example, is among the key parameters that should be fine tuned and kept consistent in the architecture. An item with a wrong naming convention would break the resynchronization rules, causing an incomplete inventory. That is why; the data migration process takes the most time in inventory management projects.

Inventory management system is the heart of the OSS infrastructure. Other OSS systems interface with the inventory management to do their jobs. For example a fault manager will import the topology from the IM to run root cause analysis on it. Trouble management systems will consult to the inventory management to have information about the spare inventory. Order managers; use it for availability checks or reservation purposes. SQM will use service-resource associations for service impact analysis, and so on.
Having a complete inventory management system reduces the messages between the OSS and EMS systems. It will eventually increase the efficiency of your whole OSS and BSS infrastructure.