These days, various academic and industrial institutions are sharing the computing resources of cloud data centers. For the sake of security, data center networks need to be separated by institution or department. One conventional approach is using tag-based VLAN standardized in IEEE 802.1Q. However, this approach cannot accommodate scalable networks beca use of a limitation on the number of VLAN IDs. To address this problem, we propose Host VLAN, a novel multi-tenant technique for scalable networks. To provide logical isolated networks for individual tenants (e.g., academic and industrial institutions), end host servers deployed in a data center filter receiving network data and forward them to designated virtual machines on the basis of isolation information. To reduce the broadcast trafik for the protocols, ARP and DHCP, end host servers convert the broadcast data into unicast data. Unlike conventional approaches that work in cooperation with switches, HostVLAN provides multi-tenant environments at the end-host-server side. To build a HostVLAN-based network architecture, we extended three virtual network switches supported by KVM and Xen VMMs. The results of performance evaluation demonstrate that Host VLAN can be scaled up to large numbers of multitenant networks with little overhead.
