@article {23942,
	title = {Efficient Routing and Reconfiguration in Virtualized HPC Environments with vSwitch-enabled Lossless Networks},
	journal = {Concurrency and Computation: Practice and Experience},
	volume = {31},
	year = {2018},
	month = {02/2018},
	publisher = {John Wiley \& Sons},
	abstract = {To meet the demands of communication-intensive workloads in the cloud, virtual machines (VMs) should utilize low overhead network communication paradigms. In general, such paradigms enable VMs to directly communicate with the hardware by means of a passthrough technology like Single-Root I/O Virtualization (SR-IOV). However, when passthrough-based virtualization is coupled with lossless interconnection networks, live-migrations introduce scalability challenges due to the substantial network reconfiguration overhead. With these challenges in mind we proposed a virtual switch (vSwitch) SR-IOV architecture for InfiniBand in (33). In this paper, we first suggest solutions to rectify the space-domain scalability issues that are present in vSwitch-enabled subnets as a result of the VMs using dedicated layer-two addresses. Then we discuss routing strategies for virtualized environments using vSwitches, and present a routing algorithm for Fat-Trees. We also present a reconfiguration method that minimizes imposed reconfiguration overhead on Fat-Trees. We perform an extensive evaluation of our prototype algorithms, and as vSwitch-enabled hardware does not yet exist, we deduce from empirical observations by emulating vSwitches with existing hardware, as well as large-scale simulations. Our results show significant reduction in the reconfiguration times as route recalculations can be eliminated, and for certain scenarios, the number of reconfiguration subnet management packets sent to switches is reduced from several hundred thousand down to a single one without degrading the routing quality.},
	keywords = {InfiniBand, Lossless Interconnection Networks, Network Reconfiguration, Network Routing, SR-IOV, Virtualization},
	author = {Tasoulas, Evangelos and Zahid, Feroz and Ernst Gunnar {Gran} and Begnum, Kyrre and Bj{\o}rn Dag {Johnsen} and Skeie, Tor}
}
@misc {24474,
	title = {Using High Performance Network Interconnects in Dynamic Environments},
	howpublished = {OpenFabrics Alliance (OFA) Workshop 2016},
	year = {2016},
	address = {Monterey, CA},
	abstract = {High performance lossless network interconnects are traditionally associated with static environments such as HPC clusters. Due to the significant network reconfiguration costs, changes in these kind of systems are rare and usually happen only when faults occur or new hardware is added. In contrary, modern multi-tenant virtualized cloud infrastructures are very dynamic by nature, and the usage of the resources is unpredictable, thus, the need to reconfigure becomes a requisite. Over the last years the OFA community has shown the potential of using high performance networks (InfiniBand) to boost the performance of virtualized cloud environments, however, the network reconfiguration challenges still continue to exist.In this session we present the work we have been doing on InfiniBand subnet management and routing, in the context of dynamic cloud environments. This work includes, but not limited to, techniques in order to provide better management scalability when virtual machines are live migrating, tenant network isolation in multi-tenant environments, and fast performance-driven network reconfiguration.},
	keywords = {InfiniBand, Live Migration, Lossless networks, Performance, Virtualization},
	url = {https://www.youtube.com/watch?v=LRmOJwgADa8},
	author = {Tasoulas, Evangelos}
}
@inproceedings {23478,
	title = {Towards the InfiniBand SR-IOV vSwitch Architecture},
	journal = {IEEE Cluster 2015},
	year = {2015},
	month = {09/2015},
	publisher = {IEEE},
	address = {IEEE Cluster 2015},
	abstract = {To meet the demands of the Exascale era and facilitate Big Data analytics in the cloud while maintaining flexibility, cloud providers will have to offer efficient virtualized High Performance Computing clusters in a pay-as-you-go model. As a consequence, high performance network interconnect solutions, like InfiniBand (IB), will be beneficial. Currently, the only way to provide IB connectivity on Virtual Machines (VMs) is by utilizing direct device assignment. At the same time to be scalable, Single-Root I/O Virtualization (SR-IOV) is used. However, the current SR-IOV model employed by IB adapters is a Shared Port implementation with limited flexibility, as it does not allow transparent virtualization and live-migration of VMs.In this paper, we explore an alternative SR-IOV model for IB, the virtual switch (vSwitch), and propose and analyze two vSwitch implementations with different scalability characteristics. Furthermore, as network reconfiguration time is critical to make live-migration a practical option, we accompany our proposed architecture with a scalable and topology agnostic dynamic reconfiguration method, implemented and tested using OpenSM. Our results show that we are able to significantly reduce the reconfiguration time as route recalculations are no longer needed, and in large IB subnets, for certain scenarios, the number of reconfiguration subnet management packets (SMPs) sent is reduced from several hundred thousand down to a single one.},
	keywords = {Dynamic Network Reconfiguration, InfiniBand, Live Migration, SR-IOV, Virtualization},
	author = {Tasoulas, Evangelos and Ernst Gunnar {Gran} and Bj{\o}rn Dag {Johnsen} and Begnum, Kyrre and Skeie, Tor}
}
