Scenarios for using historical inventory and topology

Owned by James Forsyth
Last updated: Jul 08, 2019
15 min read

By @Philip Blackwood , AT&T

This document outlines how to use historical inventory and topology data to support various use cases.  The purpose of the exercise is to ensure that all needed capabilities have been identified, and close any gaps discovered.

All use cases assume the feature has been implemented as described in the white paper “Temporal logic for attributes in a data base.”  The historical data discussed below has timestamps for when conditions were true in the network as well as the timestamp of when data was written to the data base.

The use cases refer to data filters and other data processing functions that are listed in the Appendix (functioning code).



General capabilities

In the write-ups below, a query is made to the data base and then time logic is applied.  The initial query to the data base is free of time constraints; for example, it could return all historical data for a given VNF.  A more complex query could return a portion of the graph related to the VNF.

The client will typically not need the complete history, and the first step is to identify all values that might be needed to answer questions about the history starting at a fixed time T (and following).  The result of this trimming is then used to answer questions like:

  • What was the complete history after time T?

  • What are the times at which changes occurred?

  • What are the changes that were made at those times?

  • What are the times when the in-maintenance indicator was set or cleared?

  • What changes were made to specific attributes?

  • At what times did the topology change?

  • What topology changes occurred?

  • What did this part of the network look like at a specific time (topology or attributes)?

  • Was any data missing (not yet known) at a particular time (e.g. when a decision was made)?

  • Which data source provided a specific value? (and history)



Investigating a problem with a VNF

Use case description:

Operations might be investigating a problem and suspect that it may have started two days ago.  The historical inventory feature should let users see the state of the network at the time of the event (attributes and relationships).

A common scenario is that once an issue has been detected in the network, Operations wants to be able to see what changes were made in the network just prior to the time of the problem.  For example, if service degradation started occurring at a certain time, was anything different in the network between the time things were operating correctly and the start of the service degradation?

To begin analysis, query the historical data base for data related to the VNF, which may include the related VFCs, VMs, servers, storage, and connections to the VNF, and even other VNFs that may affect the functioning of the main VNF of interest.  Note that the processing below does not assume the data base query needs to apply any time logic (if it can, the key logic needed is to be able to find data with a start time at or later than the latest start time before a fixed time T, for each attribute).