I'm looking for a way to advertise a static route in the way that OSPF does. Basically I want to set up a 172.x.x.x/28 network and I want my node to advertise that specific network to the mesh. The reason is I have a Mikrotik router and I want to have both the benefits of no NAT and those of this router. Is this practical? I would, of course, need to make sure it doesn't overlap with the vtun addresses.
What particular Mikrotik hardware are you looking at? I've been looking at these devices myself.
Joe AE6XE
Even if you were to tweak it in the backend there is no guarantee it would work long term as the 10.0.0.0/8 and 172.16.0.0/12 ranges are reserved for AREDN operations in the V3 protocol and may be out to additional use at any time.
It is important to remember the AREDN software mission is to provide the tools to build a network that is fully independent of any existing infrastructure or network. The protocol defines certain standards and requirements for interoperability. Its also better not to think of mesh nodes as routers, think of them as a modem. Yes they run a lot of software on them, but the end of the day the AREDN node missions it to turn your ethernet connection into a self configuration RF interface.
"Anyway, there needs to be a way to use other routers on the mesh, not just OpenWRT." You could very easily use a 13 host configuration and have a router plugged into the mesh node and it would have 13 IP addresses to do whatever it wants with. You may need to remove your "no nat" restriction however depending on your needs but we certainly do not stop you from utilizing a router there to do whatever you want with it. A common "router" use is a WIFI access point router is put on one of the IP addresses.
Another way to think of this is, you get a internet connection from your ISP, Do they let you advertise any IP range you want or do they say "You have been allocated X/Y/Z and may use it as you need to" A mesh node allocates you X/Y/Z as part of the standard. You can do whatever you want with those IP addresses (and even back haul your internal private network to a system on the other end using some sort of non encrypted tunnel since that is an overlay that the mesh doesn't need to know about) but those are the IP addresses to work with.
"If there's not enough address space to add the extra /30s, then why not use the 192.168/16 block?" Well the use of the 192.168..0.0/16 block hasn't come up yet
For ease of a demonstration lets assume you have only one link from your node to a central node that connects you to everyone, lets assume we allow advertising full netblock and you choose to advertise 192.168.1.0/24. Lets then assume I also chose the same netblock for my truck which has a lot of network gear in it (BTW my truck is NAT mode because of this reason in real life and the fact 99% of that gear doesn't need to be directly reachable on the mesh). I drive closer the mesh node that hears you, its going to see "Hey this KG6JEI truck can get me to 192.168.1.0/24, no need to make the long haul to K7DXS" and now your network is no longer reachable.
You could certainly make a proposal for an increase in the host selections box count (so far no one has really provided a reason to my knowledge for a need of more than 13 hosts) in the AREDN ticket system bloodhound if you feel there is a need for larger host counts so you could do either a 1:1 NAT or directly assign your nodes into the mesh side subnet.