image/svg+xml ComputeNode GRE tunnel TenantKey=X Set GRE Key Ryu OVS OpenFlow Deliver/drop packetsbased on GRE key En/de-cupsel packetinto/from GRE tunnel ComputeNode Compute+networknode Tenant VM Tenant VM Tenant VM Tenant VM Tenant VM Tenant VM OVS OVS TenantKey=Y Key is used as GRE key agent agent L2 isolation by GRE tunnel L2 over L3 with GRE tunnel- Able to span over network segments (virtual l2 segment can span over multi data centers)- can coexists withconventional networktechnology