ment. 2. Generating a representative measurement packet stream between SDN-Mon VMs located in proximity to groups of network elements. This deployment scenario could be used to validate SLA compliance between locations such as between two cities, but not specific to any communicating pair of network elements. In past implementations, one would expect at least one of the network elements at each location to embed interoperable protocols that generate such measurements, complicating network element development. As observed from the above examples, SDN-Mon enables the decoupling of such measurement functions from the network element. The SDN-Mon VM would encapsulate such measurement functions, while unburdening the network element from implementing such functions. This allows the network element to focus on its primary function, which in this case is forwarding packets. 16.6 TELEMETRY MEASUREMENTS Transporting and handling measurement messages generated by VNFs and Operations, Administration and Maintenance (OAM)-VMs to collection systems, poses challenges. Given the large-scale, geographically distributed set of message producers that are connected to the high-speed ETHERNET CONNECTION (w/CHAINED SDN-Mon): TWAMP MEASUREMENT AGENT ETHÉRNET CONNECTION (w/NO CHAINING OF SDN-Mon): TWAMP MEASUREMENT AGENT FIGURE 16.12 Sample of SDN-Mon deployment scenarios. Network Measurements core network via a diverse set of access technologies, it is important that we look at this transport design to ensure that it can handle the volume of messages that will surely only increase over time. It is to be expected that any implementation will see quite a bit of diversity in message volumes, based on the source and type of the messages generated. For the purposes of simplifying the telem- etry technology selection, this can broadly be classified as follows: 1. Low volume message producers. Such producers would include traditional alarm streams, such as SNMP traps and SYSLOGs that are converted to functionally equivalent messages for a SD