So a smart/managed layer 2 then ;)
BTW, if your going to route and your wanting to access something on your downstream from a IP that is on your transit network you are always going to run into asymmetrical problems..
asymmetrical.png
If you want to route to other networks on your downstream, then that needs to be connected to your upstream router via a transit network.. If you going to want to get to it from devices on your transit network.. Then you need to host route on them, or you run into the above asymmetrical problem.
Connect your upstream to your downstream via transit network (no hosts on it) and your asymmetrical issues are gone
17216.png
Also if you created your SVI on the L2 that your 10 network is on, then its IP would be in the 10 nework.. If you created put the svi on a different L2, then you need to route it via a transit or host routes or your going to have the asymmetrical problems.