I’ve just went through a couple of books about IMS. They mostly don’t mention restoration scenarios at all. But for engineers who really work with IMS the rainy-day scenarios are quite important. We have to know ‘what-if’. In this case what happens if the primary S-CSCF is either restarted or it is not available at all. The scenarios come into play quite often because some maintenance downtimes or even occasional failures are unavoidable. But still we should handle them without any real effect on the service. The 3GPP TS 23.380 document specifies a set of standardized procedures for automatic restoration after loss or corruption of data.
Let’s start with the registration procedure. Firstly it can happen the S-CSCF, whose name is returned by HSS (or selected by I-CSCF), is not for some reason available. In that case the I-CSCF sends one more UAR with Authorization Type set to REGISTRATION_AND_CAPABILITIES to the HSS to explicitly request S-CSCF capabilities. After re-assignment of another S-CSCF according to the S-CSCF capabilities, the I-CSCF forwards the REGISTER to the new S-CSCF.
Do you remember IT 20 years ago? AltaVista, Win95, Linux 2.0, … and Deep Space Nine 🙂 Things have changed a lot. In 90s I was interested in Artificial Neural Networks and Artificial Life. Nothing could be farther from the real life that time. But our technology is developing very fast. So it is genetic engineering and biology. Our scientist are now able to create a real artificial cell. Or at least they have JCVI-syn3.0 – a working approximation of a minimal cellular genome, a compromise between small genome size and a workable growth rate for an experimental organism.
Deep Space Nine
I can imagine that after some time we’ll be able to monitor and analyze the behavior of our cells in the same way as we’re monitoring the computer networks these days or as we want to do it with IoT. I doubt we’ll use SNMP, but surely some intelligent cells could trigger an alarm once they’ll register low sugar level or they’ll notice reduced activity of dopamine-secreting cells.
The research takes long and it is hard to predict the results. But our smart phones are not that far from tricoders in the DS9, are they? Looking at what the mankind was able to achieve within just one generation why not to be optimists? A better technology doesn’t mean better life anyway.