MEASUREMENT FRAMEWORK OVERVIEW Traditionally, the network elements deployed are optimized for a core set of functions such as rout- ing or switching packets. However, because of the various user communities-such as customers, operations groups, and network designers, and their unique requirements, additional measurement requirements are imposed on the specific network element. As illustrated in Figure 16.7, the network element shown in the inner box is focused on routing packets, for example, as part of providing a VPN service, and is optimized to do that task. To ensure that the network is conforming to SLAs and that there are no connectivity impair- ments, we start to add service measurement requirements on top. This could include building an instance of the Two-Way Active Measurement Protocol (TWAMP) [13] sender and responder func- tion instrumentation into the network element to measure SLA compliance. However, this is still not sufficient to monitor the proper functioning of the network, and to ensure that the network operations group has all the appropriate information to diagnose problems within the network, we would be required to overlay additional instrumentation. Some examples would include Operations Efficiency Improvement: Connectivity (CFM), Control Plane Measurements, etc. OPERATIONS MEASUREMENT REQUIREMENTS CONTROL PLANE (e.g., BGP, OSPF) SERVICE PACKET FLOW NETWORK ELEMENT (routed through the Network Element) Measurements Embedded in Network ELement: Interface Stats, SERVICE Queue Stats, etc. MEASUREMENT REQUIREMENTS Service Management: SLA (TWAMP), etc. FIGURE 16.7 Network elements embedded with supporting measurement instrumentation. Network Measurements instrumentation to measure connectivity across the network utilizing a protocol such as the IEEE Connectivity Fault Monitoring (CFM) [14]. Another example would include instrumentation to mea- sure the proper functioning of the control plane, such as monitoring OSPF protocol announcements. As can be seen from the above examples, the network ele