The UK government is keen to keep an open border similar to the present one after Brexit. It has set out how this can take place.
The Republic of Ireland and Northern Ireland have enjoyed a Common Travel area for many years. It pre dated our entry into the EEC. There is no wish to change this on exit. People will be free to cross the Ireland/Northern Ireland border as today. New UK migration controls are likely to rely on benefit controls and work permits if people wish to settle in the UK.
The current border is a VAT and currency border at the moment. Goods and services entailing cross border transactions require today paperwork or electronic filings to handle the different tax regimes and any currency adjustments. If we end up with the WTO model for Brexit,it will be possible to add a customs tariff line to the documentation that already is generated for a trade transaction across the border.
The likely approach will be for the larger importers and exporters to register as Authorised Economic Operators. They will be able to file electronic paperwork about truck consignments in advance of travel. Number plate recognition technology can be used at road border points to ensure the necessary registrations and payments occur without the need for physical barriers or stops.
Smaller consignments by small businesses living near the border can be exempted.
The UK has offered a friendly and sensible approach to preserve the advantages of the current border arrangements. The EU could adopt the same or could suggest other improvements for mutual agreement.