An Orchestrated Provisioning Framework for Multi­domain Software­defined Transport Networks: A stateful PCE­based Approach

Abstract

Now a day, software-defined networking (SDN) paradigm has been enhanced to software-defined transport networks (SDTNs) to control and manage network resources with the carrier’s preferences [1]. However, provisioning technique is not sufficiently developed to include a scaling architecture for multi-technology/multi-domain networks [2]. Recently, there have been some hierarchical solutions based on stateful path computation element (PCE) to lead to acceptable scalability in setting up transport tunnels across multiple domains [3]. The hybrid architecture [4] enables the orchestration of SDN controllers using east/west interface (i.e., the interworking among controllers). Although this approach scales up multiple heterogeneous control networks, the centralized PCE is needed to support seamless end-to-end service provisioning across multiple domains as a proxy single point of entry while supporting topology discovery and signaling capabilities through the east/west interface. In this paper, we propose a stateful PCE-based orchestrated provisioning framework for multi-domain SDTNs as shown in Figure 1. The key concept of the framework is the hierarchical distributed provisioning framework, in which distributed child PCE (cPCE) supports network-wide topology discovery, path computation and provisioning as well as fault monitoring capabilities except for switch-specific configuration control (e.g., OpenFlow controller). A centralized parent PCE (pPCE) relays the abstracted topology and harmonizes the end-to-end provisioning commands to the corresponding cPCEs in a hierarchical way. The proposed framework improves the network flexibility and reduces the operational expenditure to the provisioning engineers by integrating inter-domain topology discovery, path computation, instantiation, provisioning, operational management, and fault recovery capabilities into a distributed way [4]. The orchestrated provisioning framework also enables multiple domains to support carrier-grade seamless end-to-end path provisioning through the harmonized PCEs explicitly as well as implicitly while enabling to scale up by sharing load among multiple PCEs. In explicit orchestration model, each cPCE is able to handle (i.e., imitation, setup, monitoring, and recovery) the label switched path (LSP) at an inter-domain aspect with explicit knowledge of the network topology and the TE status. On the other hand, in implicit orchestration model, each cPCE has no explicit knowledge of the switches in other domain. It is aware of only the cPCE with an abstracted view, in which the cPCE acts a provisioning controller for each domain. To validate the feasibility of the proposed framework, we implement a test-bed, and show that the framework gives a scalable approach for monitoring, diagnosing and managing the multi-domain SDTN as well as a significant reduction of control traffic load and processing latency for end-to-end provisioning across multiple domains. The framework also gives the maximum flexibility and manageability for path provisioning, manipulating and updating configuration to the provisioning engineer while performing a novel seamless provisioning operation across multiple domains.