|Thesis abstract: |
Service providers are facing the ever increasing demand for Internet resources, which unfortunately do not correspond to an increase of their revenues at the same rate. To preserve their margins, they must be able to substantially reduce CapEx and especially OpEx, but current architectures and protocols are preventing this by setting constraints which lead to sub utilization of resources. As a consequence, operators have set the alarms of change and start looking at Software Define Networking (SDN).
SDN architecture is buzzing the networking world with the promise of programmability and innovation. Though SDN was conceived and is now only commercially available for packet-oriented networks, also transport providers have strong interests to deploy the SDN architecture in their circuit-oriented and optical networks, to improve network efficiency and allow fast deployment of new services. However, SDN for transport network (T-SDN) still represents a major challenge, due to the heterogeneous multi-domain (vendor, technology), multi-layer and analog nature of transport networks.
The aim of this research work is two-folded. A first set of activities comprises a comprehensive review of T-SDN proposals to support the definition, development and assessment of a T-SDN architecture with the collaboration of Telecom Italia (using state-of-the art and open source frameworks). The second set of activities involve the proposal of heuristic algorithms and operational research formulations that exploits the multi-layer network view and programmability of a centralized control plane to provide dynamic optical resource allocation, as well as cross-layer and multipath routing techniques as SDN applications.
We propose to use traffic and human mobility patterns extracted from the network history, as well as foreseen big crowd and maintenance events to improve the dynamic resource allocation techniques and minimize the service disruption between network states.
Regarding multipath routing, we target differential delay (DD) aware techniques to minimize and compensate the major drawback descending from the concurrent use of physically disjoint paths. Multipath TCP (MPTCP) adds the capability of using multiple paths to a regular TCP session, but lower layers do not guarantee that the multiple paths which are set up in the network actually guarantee better performance. Therefore, we aim at proposing and assessing multi-layer cooperation techniques to provide real multipath capabilities from the transport layer (TCP) to lower layers.
Throughout this work, special focus is given to the optical domain, which nowadays is still controlled in a static mode and isolated form other network domains. To test the proposed techniques, we are exploiting several instruments: namely, discrete event simulation, emulation using Mininet and an experimental SDN testbed for experimental purposes (Joint Open Lab of Telecom Italia).