Unspecified bit rate
Unspecified Bit Rate ( UBR ; English for "unspecified bit rate") is a quality of service class for data transmission with ATM . Other quality of service are constant bit rate (CBR), variable bit rate (VBR) and available bit rate (ABR). If there is a connection with the quality of service class UBR, this means that although the data is transmitted at the bit rate that the line has, the cell throughput is in no way guaranteed. In the ATM network, all connections that have better quality of service classes are preferred. All other quality of service classes are better, UBR is the least valuable. As a rule, a certain part of the available data transmission rate in the ATM network is reserved for this UBR traffic, and all UBR connections have to share it. If the total UBR traffic is small compared to the reserved data transmission rate, the throughput is very good. However, if the UBR traffic exceeds the reserved data transmission rate, delays occur as with IP traffic on the Internet. In the event of peak loads, data is also lost.
DSLAMs work with ATM and can therefore control the available data transmission rate with the help of quality of service classes.
literature
- Bernhard Walke: Cellular networks and their protocols 2nd 3rd edition. Springer Fachmedien, Wiesbaden 2001, ISBN 3-663-05907-3 .
- Abhijit S. Pandya, Ercan Sen: ATM Technology for Broadband Telecommunications Networks . CRC Press, Boca Raton 1999, ISBN 0-8493-3139-0 .
- Bernd Heinrichs: Multimedia on the Net . Springer Verlag, Berlin / Heidelberg 1996, ISBN 3-540-58349-1 .
- Volker Jung, Hans-Jürgen Warnecke (Hrsg.): Handbook for telecommunications . Springer Verlag, Berlin / Heidelberg 1998, ISBN 3-642-97703-0 .