Research On Test Scheme For IP-Level Hybrid Network

With the rapid development of network technology and network application,the scale and structure of the network are becoming more and more complex.The business demand is increasing through wireless network accessing wired network.Meanwhile,users pay more attention on the QoS of the wired and wireless hybrid network.The heterogeneity and complexity of the hybrid network affect the QoS provided by hybrid network.Network measurement is the basic means to understand the network characteristics and performance.Designing efficient hybrid network measurement schemes has important research significance and application value.Because the interaction process of network services is usually end-to-end(E2E),this paper focuses on the design of E2 E hybrid network measurement.Firstly,this paper researches on the network topology measurement of IP interface level.The E2 E network topology is extended based on hop-byhop measurement mechanism of Traceroute for path network topology discovery.And then the active IP is selected and the hop-by-hop measurement mechanism is improved to reduce probing redundancy.Secondly,the E2 E available bandwidth(ABW)measurement technique and methods are studied.And a unique probing scheme called HybProbe is proposed,which combines two types of probe trains for ABW.One is with exponentially increased packet rate,and the other is with linearly increased packet rate.In the probing scheme with exponentially increased packet rate,we can cover a wide range of rates with small amount of packets.The delay variation of probe packets is used to get the rough ABW estimation.In the linear probing scheme,packet rates are assigned densely with a series of linear rates around the rough ABW estimation to search for more accurate ABW.NS-2 simulation and network experiments are performed to evaluate the performance of HybProbe measurement approach.Results show that HybProbe can accurately estimate ABW and quickly track the fluctuations of ABW.Finally,One-way delay(OWD)measurement of hybrid network is analyzed.This paper make a study of the effect of nonsynchronous clocks for measuring E2 E OWD.Aimed at solving the above problem,a new oneway delay measurement method based on maximum likelihood estimation is proposed.The sender and receiver periodically send the probe packets at the same interval according to their local clocks.The maximum likelihood estimators of clock skew and clock offset are derived by detecting the packet reception time and its variation.Simulation experiments validate that the proposed one-way delay measurement method based on maximum likelihood estimation can eliminate the influence of nonsynchronous clocks and improve the precision of one-way delay measurement.