| Engineering Journal 3.2.1: Traffic characterization In WAN design, nothing is more critical than characterizing the types of traffic that will be carried by the WAN. Types of traffic include: Voice/fax Transaction data (for example, SNA) Client/server data Messaging (for example, e-mail) File transfers Batch data Network management Videoconferencing Analyzing and categorizing traffic is the basis for key design decisions. Traffic drives capacity, and capacity drives cost. Time-proven processes for measuring and estimating traffic exist for traditional networks, but not for WANs. Traffic characteristics include: Peak and average volume Connectivity and volume flows Connection orientation Latency tolerance, including length and variability Network availability tolerance Error rate tolerance Priority Protocol type Average packet length Because many network planners do not have the planning and design techniques needed to deal with WAN traffic complexities and uncertainties, they typically guess the bandwidth capacity, which results in costly, over-engineered networks or poorly performing, under-engineered ones.