Message exchange sequence. This section describes the messaging associated to the virtual optical slice provisioning and management operations. The Virtual Infrastructure Manager of the COSIGN SDN controller is responsible for managing the actions performed over the virtual optical slices. In brief, the Virtual Infrastructure Manager receives these messages from an external entity (such as the orchestrator or a tenant application) through the northbound interface, acts as a trigger to perform such operations in the controller, and manages the virtual optical infrastructure as long as it is active. Figure 3 shows the messages that are exchanged for the creation, update and deletion of virtual optical slices.
Message exchange sequence. The provisioning of DCN optical connections is a service implemented by a module in the COSIGN SDN controller called Optical Provisioning Manager and is typically invoked by external components, like the orchestrator or a cloud platform for the management of the DCN infrastructure. The sequence of messages exchanged between these entities during the provisioning and lifecycle of an optical connection is shown in Figure 7.
Message exchange sequence. Figure 20 shows four cases for OF operations that may involve the extensions defined in section 4.4.2 for match header fields, actions, creation of connectivity, and port configuration. Case 1 This case illustrates two OF messages (Figure 20): a Packet In message arriving at the controller (from the OF device), which carries a match structure conveying information about the headers of the packet, and a Packet Out message, which carries the actions to be applied to the packets. These two messages may contain extensions for matching headers and actions as defined in section 4.4.2. Case 2 In the second case, the Flow Mod message (Figure 20) contains both match header fields and actions data structures, thus it may contain any of the extensions described in section 4.4.2 subsection A. The Flow Mod message can be sent by the controller in a proactive way, or as a reply to a Packet In message sent by the OF device. As mentioned, the data structures which convey information about the actions and the matching fields in the OF messages captured in Figure 20 (case 1 and 2), may be based on the OF extensions defined for COSIGN (section 4.4.2), in addition to the basic OF protocol (v 1.3.4). Case 3 The third case depicts a new type of OF message: ofp_cflow_mod (CFlow Mod). This type of message is defined in [OFP-CS] and it is used to configure a cross connect table inside an optical switch. The ofp_connect data structure (defined in section 4.4.2), which conveys connectivity configuration, is carried as an action inside the ofp_cflow_mod OF message (case 3 in Figure 20). Hence, the OF extensions for SDN/WDM/TDM, belong to this case. Case 4 In order to configure a port, the SDN controller must send a Port Mod OF message to the OF device (case 4 in Figure 20). The extensions defined in section 4.4.2 for optical port configuration belong to this type of OF message. Figure 20 - Example of Packet out and Flow mod operations
