Andrea Sgambelluri

OpenFlow-based segment protection in Ethernet networks

Metro and carrier-grade Ethernet networks, as well as industrial area networks and specific local area networks (LANs), have to guarantee fast resiliency upon network failure. However, the current OpenFlow architecture, originally designed for LANs, does not include effective mechanisms for fast resiliency. In this paper, the OpenFlow architecture is enhanced to support segment protection in Ethernet-based networks. Novel mechanisms have been specifically introduced to maintain working and backup flows at different priorities and to guarantee effective network resource utilization when the failed link is recovered. Emulation and experimental demonstration implementation results show that the proposed architecture avoids both the utilization of a full-state controller and the intervention of the controller upon failure, thus guaranteeing a recovery time only due to the failure detection time, i.e., a few tens of milliseconds within the considered scenario.

Experimental Demonstration of Segment Routing

Segment routing (SR) technology has been recently proposed to enforce effective routing strategies without relying on signaling protocols. So far, the SR technology has received limited attention within the scientific community. In this paper, two SR implementations are presented and successfully demonstrated in two different network testbeds. The first implementation focuses on a software defined networking (SDN) scenario where nodes consist of OpenFlow switches and the SR controller is a specifically designed enhanced version of an OpenFlow controller. The second implementation includes a novel path computation element (PCE) scenario where nodes consist of commercially available IP/MPLS routers and the SR controller is a new extended version of a PCE solution. Both implementations have been successfully applied to demonstrate dynamic traffic rerouting. In particular, by enforcing different segment list configurations at the ingress node, rerouting is effectively achieved with no packet loss and without requiring the use of signaling protocols. Effective scalability performance is achieved in both proposed implementations, under different segment list conditions.

Generalized SDN control for access/metro/core integration in the framework of the interface to the Routing System (I2RS)

Software defined networking (SDN), originally designed to operate on access Ethernet-based networks, has been recently proposed for different specific networking scenarios, including core or metro/aggregation networks. In this study, we extend this concept to enable a comprehensive control of a converged access, metro and edges of a core network. In particular, a generalized SDN controller is proposed for upstream global QoS traffic engineering of passive optical networks (PONs), Ethernet metro/aggregation segment and IP/MPLS networks through the adoption of an unique interface, in the framework of the Interface to the Routing System (I2RS). Extended OpenFlow functionalities and Path Computation Element Protocol (PCEP) interfaces are encompassed to achieve effective dynamic flow control.

SDN controller for context-aware data delivery in dynamic service chaining

Recent advances in network control and management technologies, such as software defined networking (SDN) and network function virtualization (NFV), are expected to make the network effectively able to cope with application service requirements in a more flexible and timely manner. We argue that SDN and NFV capabilities can be exploited in Next Generation Service Overlay Networks (NGSONs) for addressing contex-aware end-to-end data delivery services with adaptive composition of middlebox services when dynamically provisioned as virtual functions. In this paper we present a Service-Oriented SDN controller that allows for the programmable provision of data delivery paths through a dynamically established sequence of virtual middlebox functions, thereby accomplishing the deployment of adaptive network service chains in NGSON. In this way, an extended set of QoS requirements can be addressed that include specifications on processing functions to be traversed by service data while taking advantages from context-awareness and self-adaptation capabilities of NGSON. A use case analyis have been carried out on an experimental testbed about the effectiveness of the proposed approach in differentiating service data processing while optimizing the use of forwarding tables in the switches.

An SDN orchestrator for resources chaining in cloud data centers

The oversubscription of intra-Data Center links and the high volatility of Virtual Machine deployments require a flexible and agile control of the Data Center network infrastructure, possibly coordinated with computing and storage resources control. In this scenario, the Software-Defined Networking paradigm opens up new opportunities to design orchestrated resources control strategies able to meet the dynamically-changing traffic demands of instantiated Virtual Machines. This paper presents the architectural design of an SDN-based orchestrator for dynamic computing and communication resources chaining, able to assure better than best effort VMs data exchanges across Cloud Data Centers. Moreover, the paper evaluates a number of different chaining strategies able to dynamically compose proper pool of resources based on their variable load. Such strategies are compared against specific management objectives using both simulations and experiments showing their effectiveness in terms of resource usage and service provisioning rate.

Experimenting the integration of green optical access and metro networks based on SDN

This paper outlines the issues in providing a seamless integration between energy-efficient optical access networks and metro networks that preserves the overall latency balance. A solution based on SDN is proposed and detailed. The proposed solution allows to trade the increased delay in the access section, due the utilization of energy efficient schemes, with a reduced delay in the metro section. Experiments in a geographically distributed testbed evaluate the different delay contributions.

Monitoring Plane Architecture and OAM Handler

The increase of new services such as content distribution and interdata center connectivity poses new requirements on the control and management of next generation networks. The application-based network operations (ABNO) is emerging as a paradigm integrating control and management functions for different types of services. Key functionalities lie in the ABNO operation, administration, maintenance (OAM) handler which is responsible for the verification and the actual maintenance of network services following specific service level agreements. The OAM handler collects and correlates alerts about potential problems and triggers actions to preserve services in case of failures or degradations. In this paper, a hierarchical monitoring architecture is presented. The architecture is proposed by building on the OAM handler functionalities. Monitoring information can be filtered and correlated at each hierarchical level guaranteeing high scalability of the management plane. Actions can be taken at each hierarchical layer based on the type of failure and of affected service. Measurements on a commercial systems are carried on to identify the generated alarms upon failure. Then, simulations show the high scalability achieved by the proposed architecture.

SDN and PCE implementations for segment routing

Segment Routing (SR) technology has been proposed to enforce effective routing strategies without relying on signaling protocols. In this paper, two SR implementations are presented and successfully demonstrated in two different network testbeds. The first implementation focuses on a software defined networking (SDN) scenario where nodes consist of OpenFlow switches and the SR Controller is a specifically designed enhanced version of an OpenFlow Controller. The second implementation includes a novel Path Computation Element (PCE) scenario where nodes consist of commercially available IP/MPLS routers and the SR Controller is a new extended version of a PCE solution. Both implementations have been successfully applied to demonstrate dynamic traffic rerouting. In particular, by enforcing different segment list configurations at the ingress node, rerouting is effectively achieved with no packet loss and without requiring the use of signaling protocols.

Segment routing for effective recovery and multi-domain traffic engineering

Segment routing is an emerging traffic engineering technique relying on Multi-protocol Label-Switched (MPLS) label stacking to steer traffic using the source-routing paradigm. Traffic flows are enforced through a given path by applying a specifically designed stack of labels (i.e., the segment list). Each packet is then forwarded along the shortest path toward the network element represented by the top label. Unlike traditional MPLS networks, segment routing maintains a per-flow state only at the ingress node; no signaling protocol is required to establish new flows or change the routing of active flows. Thus, control plane scalability is greatly improved. Several segment routing use cases have recently been proposed. As an example, it can be effectively used to dynamically steer traffic flows on paths characterized by low latency values. However, this may suffer from some potential issues. Indeed, deployed MPLS equipment typically supports a limited number of stacked labels. Therefore, it is important to define the proper procedures to minimize the required segment list depth. This work is focused on two relevant segment routing use cases: dynamic traffic recovery and traffic engineering in multi-domain networks. Indeed, in both use cases, the utilization of segment routing can significantly simplify the network operation with respect to traditional Internet Protocol (IP)/MPLS procedures. Thus, two original procedures based on segment routing are proposed for the aforementioned use cases. Both procedures are evaluated including a simulative analysis of the segment list depth. Moreover, an experimental demonstration is performed in a multi-layer test bed exploiting a software-defined-networking-based implementation of segment routing.

Experimental demonstration of multi-domain segment routing

Segment Routing allows simplified traffic engineering in multi-layer networks. This work proposes two novel procedures to extend segment routing for multi-domain multi-layer networks. The performed evaluation includes a scalability simulation study and an experimental demonstration.