Trunking between Nexus 9K and ASR 920 being difficult

So, here I am, minding my own business, migrating from an ASR-1002x and I come to realize ASR 920s require the BDI format.

So, I setup the basics on the n9k. NOT using the mgmt0 port, I want to access the switch via an SVI, so I type

feature vlan-interface

Then I add my SVI and assign an IP, no shut it, and configure my uplink port to the router as a trunk.

I then proceed to configure the router for subinterfaces, and I get invalid syntax.

So I look at reference material and realize the 920 doesn’t support subinterfaces, but instead BDIs.

So I configure my BDI something like this:

interface GigabitEthernet0/0/0

service instance 1 ethernet encapsulation dot1q 401 bridge-domain 401 ! end

interface BDI401 ip address 10.11.51.1 255.255.255.0 end

Both ports turned up, trunk on the nexus doing its thing,

I then go to check basic things like pinging from the switch’s vlan interface to the router and… no luck.

I then check the ARP tables. I can see the Nexus’ entry on the BDI, but I can’t see the router’s entry on the Nexus’ arp table.

The question is this: Has anyone ever encountered a similar scenario? Seems like something that should just work as-is