• Delays, RTT, loss, jitter, availability
• “Bandwidth” estimation
– TCP & UDP throughputs
– Packet pair techniques
– Packet length techniques (pchar …)
• Topology /tomography, routing
• Utilization, errors
• Security
• Evaluation of new protocols
• Applications (many commercial packages)
– Email, DB, www …
• One off: traffic characterization at borders and IXPs
– Exception, providers do not make information public