Presence Interdomain Scaling Analysis for SIP/SIMPLE

The document analyzes the traffic that is generated due to presence subscriptions between domains. It is shown that the amount of traffic can be extremely big. In addition to the very large traffic the document also analyzes the affects of a large presence system on the memory footprint and the CPU load. Current approved and in work optimizations to the SIP protocol are analyzed with the possible impact on the load. Separate documents contain the requirements for optimizations and suggestions for new optimizations.