Abstract: Based on the analysis of the measurement principle of IPv4 network bandwidth and with the combination of the next generation network protocol IPv6,we put forward a on}way and different length packet pair subtraction method for available bandwidth measuring of IPv6 network. An IPv6 network available bandwidth measuring prototype system was designed and programmed by using the flow label field of IPv6 messages to control the sequence path of tested messages. The test results show that the algorithm is feasible for IPv6 network with the measuring error less than 0. 1M. The measuring results arc realistic and better to reflect the real-time correlation of network available bandwidth and time delay, providing a useful means of network monitoring and performance measuring.

Key words: IPv6,Available bandwidth,Flow label, Bandwidth measuring