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Virtual Network Embedding in Federated Virtualized Platforms


Chrysa Papayanni, Leonidas Lymberopoulos & Vasilis Maglaris (NTUA), Cristina Cervelló-Pastor & Sebastià Sallent (UPC)

Efficient allocation and scheduling of physical resources to multiple Slices - Virtual Networks (VN) maximize the number of coexisting overlays, enable efficient load balancing and increase the utilization of substrate infrastructures. The allocation of resources with constrains on virtual nodes and virtual links is referred to as Virtual Network Embedding (VNE). VNE can be reduced to the NP-hard multi-way separator problem even when all requests are known in advance and the state of shared resources is accessible to the VNE algorithm.

Admission control on VN requests to the substrate network should (i) facilitate hard and soft Quality of Service (QoS) requirements and (ii) respect the limitations of physical resources. Hard QoS constraints imply that a user is either satisfied or denied service. Soft QoS constraints imply that a user may be admitted in a shared virtualized resource at the cost of degrading performance perceived by all users of this resource. Note that VNE requests may require near real-time handling, possibly in a way depending on the usage policy, the lifetime of a VN etc.

Within NOVI the problem is even harder. This is due to reasons such as:

  1. The VNE algorithms may be required to allocate, schedule and migrate resources in heterogeneous environments in an intelligent and efficient way. Intelligent algorithms are needed, tailored to the VN request (e.g. timeframe, administrative domains etc.) that support flexibility / robustness in handling new VN requests (e.g. migration of allocated resources to accommodate new requests).
  2. The algorithms may not have access to full state information due to (i) the multi-domain nature of the NOVI environment and (ii) the vast number of resources of several types (e.g. Node: switch, router, VServer, VM machine). These may result into partial state information within domains and exchanged amongst domains.

NOVI will provide and build an emulation environment to assess multi-domain VNE algorithms and tune them to fit anticipated user/operator requirements. In this context, an early prototype will be developed and deployed in an experimental FI platform (e.g. federation of PlanetLab and FEDERICA). In the sequel, these algorithms will be incorporated within the NOVI integrated toolset.