We recently discussed the differences between PNI (Physical Network Inventory) and LNI (Logical Network Inventory) solutions that appear as part of many OSS stacks.
As promised, today we’ll talk about the subtle differences between:
- Inventory Management Systems
- Asset Management Systems and
- Configuration Management Databases (CMDB)
- We might even discuss Virtual Infrastructure (VIM) and Resource Managers as well as Config Managers (different from CMDB) too
To be honest, the diagram above doesn’t show adequate overlap. Each of these systems has a slightly different purpose, usually for a slightly different set of personas. However, they all play a part in managing the resources that make up an organisation’s Active Network (the network segment dedicated to carrying customer traffic, as opposed to internal corporate traffic).
Let’s start with Inventory Management Systems (IMS) because IMHO, these are the tools that were traditionally responsible for managing service-provider networks. These are the tools typically used by network planners, network engineers, capacity planners and other back-office operational staff. As mentioned in the link above, these tools can be further broken down into:
- PNI (Physical Network Inventory) – The physical devices like switches, routers, firewalls as well as the outside plant (OSP) like cables, joints, etc. Generally only used by operators with large, wide-spread networks of physical assets, especially outside plant.
- LNI (Logical Network Inventory) – The set of objects that are formed using physical infrastructure (and possibly associations to other logical objects). This could include circuits, VLANs, and other overlay network topologies as well as the management of attributes like bandwidth, protocols and other network functionality
These tools tend to focus on the key physical/logical/virtual resources that comprise an operator’s active network (AN). However, they often also support functionality that crosses into other domains such as asset and config management.
Asset Management Systems (AMS), as the name implies, have a more “financial” purpose; where assets are objects of intrinsic financial value to an organisation. AMS tools tend to be used by the accounting and asset management teams. They’re used to track current value (purchase price minus depreciation), warranties, spares management, life-cycles / refresh / end-of-life of assets and their contracts, as well as reactive and predictive maintenance. AMS will tend to store information about most of the Active Network Physical devices. This means they will have records for the same devices as PNI, but often with different information / attributes. They won’t tend to store LNI-related data. However, AMS will often keep information about assets in addition to Active Network devices. This could include software licenses and more.
Configuration Management Databases (CMDB) is more of an IT Service Management (ITSM) terminology. Like many IT concepts, ITSM has been increasingly used in parts of service provider networks. CMDBs are a database of Configuration Items (CIs), where CIs can be logical or physical entities. CIs may (or may not) be physical devices (PNI) or logical resource entities (LNI) and may (or may not) represent tangible values (assets). The main purpose of CIs is to store information about IT services that will allow other ITSM processes, such as Incident, Problem and Change Management, to be performed efficiently.
Not only is there functional overlap between these systems, there’s often also terminology overlap and/or misalignments. Different vendors have different levels of functionality and support alternate use-cases, so the areas of overlap differ between organisations.
Oh, and I also promised to mention VIMs and Config Managers:
Virtual Infrastructure Managers (VIM) are responsible for managing the virtual resources made available by physical infrastructure like compute, storage and network devices. In some cases, VIMs generate virtual network devices (VNFs) or virtual machines (VMs) that could look almost identical to any other device stored in LNI, PNI, AMS and/or CMDB. In fact, instances of these VNFs and VMs may even appear in those systems.
Config Management (as opposed to, but also potentially overlapping with, CMDB), is all about managing the configurations of devices in the network (often active network and corporate network). Each device, such as a router, has a configuration that tells the hardware how to function, where to route traffic, which packets to prioritise, where to send management logs (to the OSS), etc. Being able to monitor and manage these configurations centrally and consistently is the purpose for Config Managers. These are mostly used by network engineers to set policies and golden-configs (ie the config templates that all devices of that type must adhere to consistently). For example, you may have hundreds/thousands of devices in your network and want to re-point all management traffic to a new server as part of an OSS upgrade. Rather than configuring each device separately and manually, you can use the config management tool to push config changes out to the network.
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