Therefore, the rate of the RTCP packet flow must be controllable to allow for a very large number of participants. RFC 1889 describes the RTCP and includes a discussion of the RTCP Transmission Interval. It includes an algorithm that calculates the interval between sending compound RTCP packets to divide the protocol's allowed control traffic bandwidth among participants. RTCP can also be used to display the name of a participant at the user interface. This is most useful in loosely controlled sessions in which participants come and go at will, or when membership control features are not part of an application. There are five types of RTCP packets. Type 1 is Sender Report or SR. It is used for transmitting and receiving reception statistics from all participants that are active senders. Type 2 is Receiver Report or RR. This type of packet is used to convey reception statistics from participants that are not active senders. Source-Destination packets comprise type three. CNAME is included in such a packet. Type 4 is used to Standards for Conferencing over IP Networks indicate the end of a session and is aptly named BYE. There is also a fifth type, known as APP. It is used to carry application-specific functions. RTCP is being implemented, along with RTP (whose services it uses), by a number of Internet videophone providers. It is becoming a popular and widely supported protocol, and is included as part of many Internet/intranet products. RSVP: IETF RFC 2205 Overview of RSVP The Resource Reservation Protocol (RSVP) relies on its companion protocols (UDP, RTP and RTCP) to promise Real-Time or near Real-Time transport over IP networks. In creating bandwidth-on-demand, it is RSVP's job to request dynamically that network bandwidth be set aside. Such bandwidth is required for building a Real-Time multimedia session between one or more devices. RSVP acts on behalf of applications to request necessary bandwidth from devices throughout the network in accordance with priority. It allows a receiver to request a specific amo