NESTOR: an architecture for network self-management and organization

Configuration management presently requires complex labor-intensive processes by experts. A single configuration task-installing/reconfiguring a system, or provisioning a service-typically involves a large number of activities fragmented among multiple network elements, each with its own proprietary configuration management instrumentation and tools. A change may cause configuration inconsistencies resulting in failures or inefficiencies; undoing changes to recover an operational state is often very difficult or even practically impossible. Therefore, configuration management is very costly, error prone, and often results in unpredictable failures and costly recovery. NESTOR seeks to replace labor-intensive configuration management with one that is automated and software-intensive. Configuration management is automated by policy scripts that access and manipulate respective network elements via a resource directory server (RDS). RDS provides a uniform object-relationship model of network resources and represents consistency in terms of constraints; it supports atomicity and recovery of configuration change transactions, and mechanisms to assure consistency through changes. RDS pushes configuration changes to network elements using a layer of adapters that translate operations on its object-relationship model to actions on respective elements. NESTOR has been implemented in two complementary versions and is now being applied to automate several configuration management scenarios of increasing complexity, with encouraging results.