I have 2 questions about zebra in frr.

1. why do we maintain 2 types (source and destination route type) in zebra. I am not sure what source route type means ? Is it the source of the route (like the packet source or the neighbor from which the route got learnt) ?

2.  How does frr routing stack interact with SONIC platform. I see that it has a TCP socket with SONIC which it uses to send messages for all protocols. Is it true ?  

Thanks,

Sudhanshu