Define your current vs. future state, get validation from an expert. Like MountNex.

Avoid “big bang” cutovers. Plan for coexistence and integration (NNIs, DC capacity, etc.). Scaling DCs takes time: check early, not late.

Commercial construct > ELAs are the mainstay of vendors especially for large scale deployments, a wide range of ELAs from different vendors, some start at £250k others £500k. Often the bigger the organisation the larger the technical debt, we often find that engaging MountNex we use our knowledge to stagger deployment and activation. Often SD-WAN first then cyber security second. Perpetual licence constructs are still a thing, sometimes sufficient for smaller budgets but less flexible in terms of deployment and service activation. For some customers this is a non-negotiable. It is always good to be forearmed on the options available to you, ask the vendor.

Migration > after you have successfully chosen your vendor via a formal RFP or PQQ you are ready to deploy. At this point the vendor or partner should be there to help you and make it a successful project, some vendors will only get involved in the larger projects others will rely on capable Partners.

Every successful project has a Statement of Works (SoW), this defines what each site will look like and be associated with a broader and much more detailed technical design. In some cases you will need to define an ‘as-is’, ‘to-be’. We always recommend doing this yourselves or in collaboration with a third-party expert. It is most common that you won’t switch the old solution off and the new one on in one go or as we like to call it a "big bang". Therefore a clear understanding of how the two technologies or environments will integrate, some networks may need a mid-way integration point (NNI if you want to get technical). Your existing Data Centres should be able to cater for this, we always say check your capacity early, as flexing up DCs can take time and may require more hardware.