> I am not sure that you were defending VTAM. All of the interesting > things that you did were done to overcome deficiencies. That seems quite > the opposite of a defense. > Richard Schuh
On the matter of defense of VTAM, one thing that VTAM (and SNA networking in general) does do well is lend itself to predictive modeling of network behavior. The lockstep model used in SNA is very amenable to standard simulation techniques, which make it very easy to determine the impact of a change, or determine the capacity of the network in the abstract. The "completely define the world" approach makes it much easier to construct full topology graphs and diagnostics tools. SNA also has much better engineered instrumentation for measurement. TCP networks are self-similar, which complicates prediction by a lot, and SNMP is a real hack. It's all we have at the moment, but it lacks a lot for sampling and performance analysis.
