of flow. The amount of bandwidth is characterized by the Peak Cell Rate (PCR) supports traffic sensitive to delay and loss, such as video conferencing, telephony (voice services) emulates circuit switching Real-Time Variable Bit Rate (rt-VBR) transports traffic at variable bit rates Carries traffic like compressed voice, video, and audio rt-VBR connections are characterized by a Peak Cell Rate (PCR), Sustained Cell Rate (SCR), and Maximum Burst Size (MBS). Non-Real-Time Variable Bit Rate (nrt-VBR) transport variable bit rate traffic, for which there are no strict real-time accurate timing requirements carries traffic like data and buffered voice and video Available Bit Rate (ABR) similar to nrt-VBR, it is also used for connections that transport variable bit rate traffic for which there is no reliance on time synchronization between the traffic source and destination, but for which no required guarantees of bandwidth or latency exist provides a best-effort transport service, in which flow-control mechanisms are used to adjust the amount of bandwidth available to the traffic originator Appendix is primarily designed for any type of traffic that is not time sensitive and expects no guarantees of service. Unspecified Bit Rate (UBR) provides no assurance that the data will be delivered (best effort only) is generally used for applications that are very tolerant of delay and cell loss, like file transfers and E-mail has no flow-control mechanisms to dynamically adjust the amount of bandwidth available to the user Each ATM connection contains a set of parameters that describe the traffic characteristics of the source. The ATM network checks with the source to determine the specific traffic requirements according to the traffic characteristics. When each connection is set up, traffic parameters are determined and a traffic contract is made. Then the ATM network shall provide QoS that falls within the agreed traffic contract. Their parameters are: Peak Cell Rate (PCR): The maximum allowable rate at which cells can be tra