Intent-based networking (IBN) has emerged as a
promising paradigm to simplify the management of network
infrastructures. At the heart of IBN systems lies the intent
handler, a management entity that transforms declarative net-
work goals into imperative network configuration that meets
specific policy and optimization requirements. Practical research
has produced a number of intent handler implementations,
that exhibit specialized use-cases with limited extensibility. This
paper presents SWIFT, a framework to simplify the development
of custom intent scenarios. To support this capability, SWIFT
delivers two main contributions. Firstly, it employs an ontology
to abstract several standardized and open network data models
(3GPP Core Configuration, ETSI NFV-MANO, ONOS NBI) and
support the translation of slice delivery intents, modelled using
the TMForum common intent model, into effective infrastructure
configurations. Secondly, SWIFT offers a reasoning framework
for network operators to implement custom intent handling logic
using logical programming. The reasoner can use the rich infor-
mation of the ontology both to automate the translation of intent
requirements, and validate intent goals based on the current
network state. Our proof-of-concept SWIFT implementation can
automate and optimize the delivery of private 5G network slices.
Furthermore, we demonstrate the optimal planning and delivery
of mobile slice intents in a real mobile network topology with
minimal processing overheads.