work with AAL5 connections as they use the end of packet marker: the ATM user-to-ATM user (AUU) indication bit in the payload-type field of the header, which is set in the last cell of a SAR-SDU. Traffic shaping Traffic shaping usually takes place in the network interface card (NIC) in user equipment, and attempts to ensure that the cell flow on a VC will meet its traffic contract, i.e. cells will not be dropped or reduced in priority at the UNI. Since the reference model given for traffic policing in the network is the GCRA, this algorithm is normally used for shaping as well, and single and dual leaky bucket implementations may be used as appropriate. Reference model The ATM network reference model approximately maps to the three lowest layers of the OSI reference model. It specifies the following layers: At the physical network level, ATM specifies a layer that is equivalent to the OSI physical layer. The ATM layer 2 roughly corresponds to the OSI data link layer. The OSI network layer is implemented as the ATM adaptation layer (AAL). Deployment ATM became popular with telephone companies and many computer makers in the 1990s. However, even by the end of the decade, the better price/performance of Internet Protocol-based products was competing with ATM technology for integrating real-time and bursty network traffic. Companies such as FORE Systems focused on ATM products, while other large vendors such as Cisco Systems provided ATM as an option. After the burst of the dot-com bubble, some still predicted that "ATM is going to dominate". However, in 2005 the ATM Forum, which had been the trade organization promoting the technology, merged with groups promoting other technologies, and eventually became the Broadband Forum. Wireless or mobile ATM Wireless ATM, or mobile ATM, consists of an ATM core network with a wireless access network. ATM cells are transmitted from base stations to mobile terminals. Mobility functions are performed at an ATM switch in the core network, known as "crossover switch", which is similar to the MSC (mobile switching center) of GSM networks. The advantage of wireless ATM is its high bandwidth and high speed handoffs done at layer 2. In the early 1990s, Bell Labs and NEC research labs worked actively in this field. Andy Hopper from the University of Cambridge Computer Laboratory also worked in this area. There was a wireless ATM forum formed to standardize