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IRTF Timing RG TICTOC - IETF - 73 17 Nov. 2008 Yaakov (J) Stein The issue Charter language our charter says the following : It is also expected that active individuals in the TICTOC WG will propose the formation of an IRTF RG to study more advanced aspects of time and frequency distribution. there have been no discussions on topics for such a RG We could call it - Sync Your Network Clock In the following slides I will mention possible topics of interest Non-goals We would probably not want to tackle : • BCP(s) about design of particular algorithms (IPR issues) • comparison of particular algorithms in various scenarios • things already being carried out by TICTOC • characterization / test scenarios (being done in ITU SG15) PDV and clock recovery performance The most common question asked by nonexperts is given a PDV how good will my clock recovery be ? The truth is that this question is not well enough defined Even if the network is stationary (no reroutes or load changes) a single number PDV is insufficient to predict In general we need the full PDV distribution and its full spectrum However, in certain cases the question is answerable In the Gaussian, IID, white-noise case the answer is easily obtained (assuming a PLL-like mechanism) For other cases of interest, simulation using existing algorithms can provide guidelines PDV characterization PDV is usually defined with certain applications in mind for example - sizing of playout buffers for real-time media The usual percentile-based definition reflects the intended use RFC 3393 discusses the PDV's median PDF/CDF but not its spectrum In addition, RFC 3393 discusses having locked clocks It would be useful to specify how and what to measure (coordination with ITU, to avoid duplication, will be needed) Time as a commodity There is speculation that ubiquitous high-quality time may transform application and protocol design In many cases this has not been sufficiently explored IxTF documentation of the implications would be useful In particular, it would be useful to research • performance measurement when network elements have time • interaction between routing and timing • interaction between DNS and timing • database cache coherency • others ? Applications to security There may be improved security mechanisms that rely on high-quality time at various points in the network Public-key cryptography and Autokey mechanisms are presently used to secure timing streams, but perhaps are not ideal - are there better mechanisms ? New timing distribution topologies It has been suggestions in the literature that time can be distributed in non-hierarchical fashion (e.g. classless time distribution) This means that we need not know a trusted server a-priori It is unclear if this can be extended to frequency distribution due to the problem of timing loops There may be other novel non-client/server topologies Other suggestions • high-quality time in mobile devices • improving time in existing IP protocols (ICMP, …) • distributing time over networks with very long delay