Reliability of Accounting
While the specification for RADIUS accounting is promising, experience sees that accounting packets are not a sure, 100% certainty. For example, if a client sends accounting packets to a server but receives no acknowledgment or response, he will continue to send the same packet for only a limited time. This results in some sessions with inconsistent records. This presents problems with operations that require great consistency and accuracy: billing is a prime but certainly not sole example. While progress is being made in improving the reliability of the accounting mechanism (mainly with interim records, which are covered in Chapter 9), you should be aware of the problem.