specifically Internet Protocol television (IPTV) Audio over Ethernet Audio over IP Voice over IP (VoIP) Videotelephony Telepresence Storage applications such as iSCSI and Fibre Channel over Ethernet Circuit emulation service Safety-critical applications such as remote surgery where availability issues can be hazardous Network operations support systems either for the network itself, or for customers' business critical needs Online games where real-time lag can be a factor Industrial control systems protocols such as EtherNet/IP which are used for real-time control of machinery These types of service are called inelastic, meaning that they require a certain minimum bit rate and a certain maximum latency to function. By contrast, elastic applications can take advantage of however much or little bandwidth is available. Bulk file transfer applications that rely on TCP are generally elastic. Mechanisms Circuit switched networks, especially those intended for voice transmission, such as ATM or GSM, have QoS in the core protocol, resources are reserved at each step on the network for the call as it is set up, there is no need for additional procedures to achieve required performance. Shorter data units and built-in QoS were some of the unique selling points of ATM for applications such as video on demand. When the expense of mechanisms to provide QoS is justified, network customers and providers can enter into a contractual agreement termed a service-level agreement (SLA) which specifies guarantees for the ability of a connection to give guaranteed performance in terms of throughput or latency based on mutually agreed measures. Over-provisioning An alternative to complex QoS control mechanisms is to provide high quality communication by generously over-provisioning a network so that capacity is based on peak traffic load estimates. This approach is simple for networks with predictable peak loads. This calculation may need to appreciate demanding applications that can compensate for variations in bandwidth and delay with large receive buffers, which is often possible for example in video streaming. Over-provisioning can be of limited use in the face of transport protocols (such as TCP) that over time increase the amount of data placed on the network until all available bandwidth is consumed and packets are dropped. Such greedy protocols tend to increase latency and packet loss for all users. The amount of over-provisioning in interior links required to replace QoS depends on the number of users and their traffic demands. This limits usability of over-provisioning. Newer more bandwidth intensive applications