| 19 | 19 | The detection of a client connection and migration within the testbed is achieved through the use of OVSBs and OF flows (flows). These flows detect, encapsulate, and redirect client DHCP packets (on UDP destination port 67) to the network-level FL controller. This controller contains an integrated DHCP server module which, unlike traditional DHCP servers, associates an IP address lease with multiple MAC addresses. Each of these MAC addresses corresponds to a participating network interface (NIC) on the client. When processing a DHCP packet, the controller cross-references the MAC address of the DHCP packet with all available MAC address lists. Upon a successful match within a MAC address list, the controller assigns the client who initiated the request the corresponding IP. Then, upon a mobile host's initial connection or migration to a foreign network, flows are inserted in OVSBs starting at the testbed root and along every hop to the client's current location. These flows direct packets to and from the mobile client within the testbed. When a client migrates away from this network, any existing flows associated with the client are removed and replaced with flows along the path from the root to the newly-migrated foreign network. The use of a root switch and tree hierarchy allows the network-level controller to avoid undesirable triangle-routing in the event of a migration. |
