On Dynamic Service Chaining in Filterless Optical Metro-Aggregation Networks

Filterless Optical Networks (FONs) in which optical nodes are formed by only passive splitters and combiners, are widely-adopted technical solution for transport networks, especially in the metro area, where relatively-low nodal degrees and limited link lengths allow to limit waste of wavelengths due to the broadcast nature of FONs. Up to now, FONs have been mostly deployed for scenarios where traffic requests are expected to be mostly static. However, considering emerging adoption of 5G services characterized by high traffic dynamics and thanks to recent advances in Network Function Virtualization, operators are now expected to perform more adaptive service provisioning and, consequently, dynamic network reconfiguration. In other words, it is possible to realize 5G services as Service Chains (SCs), using software components running on commodity servers in an agile way. In this work, we investigate the behavior of FONs under dynamic settings, considering that SC requests vary dynamically during the day. To this end, we provide an algorithm to perform dynamic service chaining in metro-aggregation networks, which considers the intrinsic wavelength broadcast nature in FONs. To provision services we need to allocate both computational and network resources to them. We consider two different traffic scenarios, with high dynamicity and low dynamicity, where the holding time of SCs ranges from a few seconds to a few minutes. Our illustrative numerical results, obtained using realistic network settings, show that FON architectures require the deployment of computational resources at all network nodes and the use of a filterless-aware SC provisioning algorithm to provide a performance in terms of provisioned bandwidth comparable to active optical networks. In particular, FONs (with additional investment in terms of computational resources) can outperform active networks under traffic with low dynamicity, while under high dynamic traffic FONs show acceptable performance slightly short of that of active networks.