Optical Interconnection of CDN Caches with Tb/s Sliceable Bandwidth-Variable Transceivers featuring Dynamic Restoration

A scalable cost-effective solution for high service availability featuring low latency is required for CDN caching. Recently, a field of study is that MAN data centers, within the latency budget, act as a backup for other local data centers of lesser reliability. Given the low latency target of caching, the optical layer is the preferred option to interconnect caches. However, carrying the backup traffic from one data center (DC) to another with a permanent optical circuit based on Fixed Transceivers (FT) features low utilization and no statistical multiplexing gain on the path, which makes the backup network resources costly. In this paper we compare several approaches to implement this scenario with dynamic circuits, considering both inter-cache and backup traffic with FTs featuring both permanent and switched optical circuits, and with the Tb/s sliceable bandwidth-variable transceivers (S-BVT) developed in the EU project PASSION. As we show, S-BVTs can be key devices to improve backup-network scalability in terms of IT resources and transceivers, thanks to their capability to adapt to the actual traffic demand and to obtain multiplexing gains at the optical layer.