Bandwidth metrics are necessary for network plan

management and performance optimization. For its merits

for example with capacity of measurement end-to-end bandwidth across several autonomous systems

a lot of algorithms on bandwidth active measurement were proposed. To compare and analyse existing methodologies is the basic for design of more precise

effective and robust bandwidth measurement algorithms. The metrics are proposed for performance evaluation of these methodologies. The lintitatiuus are discussed from principle and experimental result with bandwidth measurement experiment. Eliminating the affection of deviation accumulation and cross tragic is research direction for improving existing bandwidth measurement methodologies. An improved bmdwidth measurement method is proposed for eliminating infections of deviation accumulation caused by hop by hop measm-ement and cross traffic.