today we have encountered an interesting issue with our stacked C3650. With the stack already having "ip routing" enabled, vrf configured and some Vlan interfaces and routes in place, after adding a new Vlan interface, and discovering new directly connected route behind it (while seeing the other side in arp table) we were unable to ping the opposite host (behind the new Vlan) from outside of the C3650. We were able to ping the Vlan interface on C3650 from any place that had the corresponding routes, but not beyond.
After SSH to the said host, I was again able to ping anything on the C3650, but not beyond, even if the routes were in place. The C3650 was refusing to route this newly added subnet anywhere, and to route anything to it (except for its own interfaces).
After issuing "ip routing" command as a Hail Mary, the routing suddenly started working.
Now, my question is : What are the inner workings of the "ip routing" command and what components/tables does it clear/reset when you issue it? I would very much like to find out the root cause and this could point me to the right direction.
Thanks in advance !
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