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ConfDB Overview

ConfDB is a common term for complex of measures for high-level device configuration processing within NOC. Vendors tend to invent their own configuration formats, often mimicking each other, and to introduce incompatibilities between releases and platforms. Besides simple change tracking and regular expression search, multi-vendor configuration processing may be a very challenging task.

NOC addresses the challenge with the following approach:

  • Decomposition - complex task may be split into simple steps
  • Reusability - all tools may be reused whenever possible
  • Pipelining - each step combined into configuration processing pipelines
  • Clean contract between steps - each step performs its own task. Steps accept a predictable result from previous steps and pass a predictable result to following steps
  • Clean API - each step must be understandable and easy to implement
  • Quick result - First result must be reached easily and quickly. Then you can become to implement more complex things

To better understand the concept of ConfDB one should refer to a widely-used concept in programming languages - Virtual Machines. Virtual Machine (VM) is the fictional computer with its own native assembly language (or machine codes). It's sometimes easier to break the task of compiling the program from programming language to target processor into two steps: to compile to fictional machine codes and to compile from fictional codes to target ones. The benefits in a clear separation of common functions, suitable for all target platforms, and of specific functions, addressed for a single platform. Common functions moved to the left (Code -> VM translation), while specific moved to the right (VM -> Target platform translation). Hence VM represents the clean contract between hardware-dependent and hardware independentent functions.

Device configuration is the programming language of target platform. So we can split the task of configuration analysis by applying clean barrier between hardware-dependent and hardware-independentent parts. Just like Virtual Machine NOC introduces fictional configuration language for non-existing (yet?) network equipment. All hardware-dependent parts are moved to the left. All hardware-independentent parts are moved to the right and may be reused.

ConfDB pipeline stages

Config processing pipeline and stages are represented on the chart below

graph TD
    Fetching --> Storing
    Storing --> Tokenizer
    Tokenizer --> Normalizer
    Normalizer --> Applicator
    Applicator --> ConfDB
    ConfDB --> Queries