Experience with implementing VNF chains with Segment Routing and PCEP

We present here an implementation to support function chaining and migration in the Network Function Virtualization (NFV) paradigm, using Segment Routing (SR) and Path Computation Element Communication Protocol (PCEP). The paradigm of NFV requires the underlying networks to be able to route traffic through dynamically deployed Virtual Network Functions (VNFs). Segment Routing is a modern incarnation of the source routing paradigm, which together with PCEP we can use to build network paths, steering the traffic through specific segments. The proof of concept we built uses SR-MPLS, focused on IPv4 SR, and consists of Juniper vQFX routers with custom VNFs. The VNFs are custom developed BPF programs that run on special VNF hosts, integrated into the SR-MPLS network. To build SRMPLS paths through the network, we use the Juniper NorthStar Software Defined Networking (SDN) controller and the PCEP protocol. We developed two scenarios to validate the functionality of our proof of concept: the migration of VNFs and the creation of VNF service chains. We demonstrate that in both scenarios we can successfully steer the traffic through the VNFs, showing the feasibility of using SR with PCEP to assist the deployment of VNFs.