That's why you make addressing hierarchial. With IP it was one address, 16bitx2 addressing will be fixed for the purpose of routing in that it either looks at t

That's why you make addressing hierarchial. With IP it was one address, 16bitx2 addressing will be fixed for the purpose of routing in that it either looks at the top level 16bit and decides the route to choose or for core routers, the destination keeps the other end of the address space in the routing table,again 16x2 on core/transit and just 16 for LAN/Host routing (higher order 16bit addresses each get their own RT, scaling as needed). Routing becomes a fast two step process ("i have a table for that, then let me lookup the route" or "I don't have the table, default route or drop"). For that small cost of additional RT lookup and memory you get faster lookups and comparisons (16 vs 32bit) and you can get small routers that support as little as 65k routes cheal for small sites and stack/scale that to meet demand. So R1 gets the packet, looks at the first 16bit and decides which R3 has the RT for that and forwards it, R3 looks at only the second 16bit due to it's role in the stack and forwards it elsewhere. Internet routers will do the most work since they will do multiple (but predictable and limited since it scales exponentially) lookups then downstream looks up less and less until the actual application gets it. 16bit to support utf16. Arbitrary length but fixed hierarchial address partitioning.