Network calculus is an evolving new methodology for backlog and delay analysis of packet-switching networks. With network calculus we are able to compute tight bounds on delays,backlogs,and effective bandwidths in a lossless setting applicable to packet-switching networks and better understand some physical properties of networks. In this paper,the basic network calculus concepts of arrival curves and service curves are introduced.Then we provide the approach for modeling leaky-bucket,generic cell rate algorithm(GCRA),constant bit rate(CBR)flow, variable bit rate(VBR) flow with arrival curve.It is shown that all rate-based packet schedulers can be by a simple rate latency service curve.And by applying these fundamental rules of network calculus,bounds on delay, buffer,effective bandwidth for leaky bucket,GCRA,CBR and VBR can be derived and some practical examples are given.Finally,we compare all the results obtained and conclude this paper. Network calculus is an evolving new methodology for backlog and delay analysis of packet-switching networks. With network calculus we are able to compute tight bounds on delays, backlogs, and effective bandwidths in a lossless setting applicable to packet-switching networks and better understand some In this paper, the basic network calculus concepts of arrival curves and service curves are introduced. Now we provide the approach for modeling leaky-bucket, generic cell rate algorithm (GCRA), constant bit rate (CBR) flow, variable bit rate (VBR) flow with arrival curve. It is shown that all rate-based packet schedulers can be by a simple rate latency service curve. And by applying these fundamental rules of network calculus, bounds on delay, buffer, effective bandwidth for leaky bucket, GCRA, CBR and VBR can be derived and some practical examples are. Finally, we compare all the results obtained and conclude this paper.