When you see a device 'routing through itself' this isn't a routing loop; it's just normally what you'll see in a route table entry (which only shows the first hop of any route) when the first hop to the destination is also the complete route. Meaning, the hub is sending a message to one of its neighbor routers-- the first and last hop are one and the same.
So that jogged my memory regarding the [null, 0000] via [null, 0000]... Whoops, I seem to have forgotten all about this when it came up some time ago: Seeing "In Discovery" in the routing table - #4 by Tony It's also normal....
High ram / Low ram concentrators are (AFAIK) features of the Zigbee stack (SiLabs refers to them as 'plug-ins') that can be enabled on some routers to make many-to-one routing more efficient. If a node is a high ram concentrator, it's telling other nodes that it has enough storage to hold a complete routing table and doesn't need a source route (back to the originating node) transmitted along with every message.
