There is growing interest in capturing and analyzing Internet traffic characteristics in pursuit of insights into its evolution. We present a study of one of the few sources of publically available long-term Internet traffic workload data, namely the NLANR PMA archive of packet header traces. Trace samples were collected at a number of academic, research, and commercial sites during years 1998-2003. We consider four metrics of traffic: bytes, packets, flows, and number of source-destination pairs. We also analyze the composition of traffic by protocol.

More than 4000 traffic samples from publicly available archive of traces collected and maintained by the National Laboratory for Applied Network Research (www.nlanr.net). The measurements were taken during the period of 1998-2003.

• We considered four quantitative metrics of traffic: number of bytes, number of packets, number of flows and number of source-destination pairs.
• A commonly accepted claim of Internet traffic constantly increasing at a high rate is not true for the majority of sites in our survey.
• Packet rate is a sublinear function of bit rate. Counts of flows and IP pairs behave approximately as square root of bit rate.
• Proportion of TCP and UDP traffic on average is about 5 to 1 by bytes, or 3 to 1 by packets. This ratio has not changed appreciably over the period of observations.