I have been working on a few projects lately that involve providing redundant processes, particularly related to communications circuits. What I have been finding with a great deal of regularity is that in almost all cases the technology that has been implemented over the years has replaced technologies that are still practical and effective. In most cases, radio systems for example, low-band VHF radio systems provided noisy coverage that didn’t work from portable radios but was very reliable. These systems were replaced by modern trunked radio systems that are very robust, offer many talkpaths, perform well in buildings but depend on complex IP based infrastructure to function. While the upgrade path to these systems was cost effective and generally makes sense, sending hundreds or thousands of those old radios to a landfill may not be the best idea the first time you have a glitch in the new system.
Each time these issues come up someone always will say – “If only we had kept….”. Let this be the warning to each individual responsible for system lifecycles, always keep the previous generation of your networks in place and operational the greatest extent possible. Having a redundant layer is ALWAYS advisable.