As mentioned in a post about Service and Resource Availability last week, I do tend to think of OSS workflows around an “orders down, faults up,” flow direction. And that means customers (services) at the top, network (resources) at the bottom of the (TMN) pyramid.

I also think of inventory (yellow) as the point where Assurance / Faults (blue) and Fulfillment / Orders (purple) collide and enhance, as per the diagram below.

These are highly generic examples, but let’s take a closer look:

Assurance flow (blue) – an alarm or event in the network (NEL/NE layer) pushes up through the stack to the OSS as a fault. The inventory (network / service) helps to enrich the fault with additional information (eg device name, location, connectivity, correlation of this and other faults, etc) to help resolve the fault (either manually by operators or automatically by algorithms). It also helps associate the fault in the network/resource with the customer/s using those resources. This allows notifications to be issued to customers. Note that this simple flow doesn’t reflect examples such as an incident (ie when a customer notices a problem first and calls it in before the OSS has been able to issue a notification).

Fulfillment flow (purple) – a customer places an order (BML/BSS layer or above) and it pushes down through the stack, including changes in the network (NEL/NE layer). Once all the appropriate network changes have been made, the order is ready for use by the customer. Once again, inventory plays an important part, associating customer / service identifiers with suitable resources from the available resource pool. Generally the (customer facing) service orders won’t have the technology-specific details required to actually update the network configurations though. That’s where the inventory often helps to fill in the knowledge gaps and send technology-specific commands down into the network. [See Friday’s post for more information about CFS and RFS definitions and mappings]

Inventory flows (yellow) – an inventory is relevant to assurance and fulfillment flows if the BSS and network / resource layers don’t hold enough information to be fully processed. The enriching information stored by inventory must come from somewhere. Some of it comes from Discovery (usually an automated process of collecting from the network or other sources), or via Manual / Scripted Input (eg physical network designs including patch cables and splicing). Some data (eg splices) just can’t be collected automatically as they relate to passive equipment that has no programmatic interface. This data just has to be created manually.
But arguably the more important inventory data is actually recording the mappings made from customers (services) to network (resources). Inventory solutions  are often where these linking keys / relationships are recorded.

These flows also tend to indicate the direction of data mastery. Whilst the network itself is the source of truth, Fulfillment flows will start at the BSS and customer / service / order data will tend to be mastered there before orders are pushed into the network as provisioning commands. For assurance flows, the network will tend to be the master source of data, but with enrichment along it’s path northbound.

Just keep in mind that there are many exceptions to these examples. Data and processes can flow in many different ways. The diagram above is just useful for helping newcomers to understand some conceptual processes and data models / flows.