  With the emergence of network function virtualization (NFV), and
software-defined networking (SDN), the realization and implementation of
service function chains (SFCs) have become much easier. An SFC is an ordered
set of interconnected virtual network functions (VNFs). NFV allows for
decoupling the network functions from proprietary hardware realizing a
software-based implementation of VNFs on commodity hardware and SDN decouples
the network control from its forwarding logic allowing for a more flexible and
programmable traffic routing among the VNFs. The SFC embedding problem (i.e.
placement of SFCs on a shared substrate and establishing the corresponding
traffic routes between the VNFs), has been extensively studied in the
literature. In this paper, we extend a previous work on trust-aware service
chain embedding with generalizing the role of trust by incorporating the
trustworthiness of the service network links and substrate network paths into
the SFC embedding decision process. We first introduce and formulate the
path-based trust-aware service chain embedding problem as a mixed
integer-linear program (MILP), and then provide an approximate model-based on
selecting k-shortest candidate substrate paths for hosting each virtual link,
to reduce the complexity of the model. We validate the performance of our
methods through simulations and conduct a discussion on evaluating the methods
and some operation trade-offs.
