Treatment Framework : Traffic Steering via Source-Routing in SDN for Service Function Chaining

Abstract: The middlebox architecture is long known for its inharmonious presence within the Internet architecture. Network functions realized in middleboxes are inclined to interpose end to end connections, modifying the datagram header or spawning new connections on behalf, which renders policy enforcement challenging. Moreover, their tight coupling with metadata makes its distributed persistence difficult, which hampers the flexible utilization and scalable provisioning of the middlebox infrastructure resources under varying loads. Existing attempts at mitigating these problems include middlebox placement, packet tagging and metadata migration; each solving only a part of the problem.Investing in the extensible nature of IPv6, the Treatment Framework (TRF) exploits source routing with the flavor of a discretionarily classifiable address space. Datagrams traverse the treatment domain with an extension header pushed and popped at the domain’s edges, for which forwarding takes place based on the information encoded within. The forwarding mechanics that leverage SDN consists of one match and three OpenFlow actions implementation, whereby TRF obviates the need for an underlying transport. Customizable address space allows providers to tailor routing aggregation to their middlebox farms topology, reducing the number of flow rules in the core to preinstallable sizes.Middleboxes in a treatment domain match traffic to the respective local policy based on the information encoded in the extension header. Extension headers are native to IPv6 and defined by standards, hence the middlebox modification problem is addressed without requiring alteration nor visibility into proprietary code. The framework resolves the policy enforcement problem altogether and allows asymmetric service chaining. While eliminating the flow setup time in the core, the framework’s footprint at ingress that push the extension header can get heavy with respect to flow churn rate.