Simple definition
VRF route leaking deliberately shares selected routes between otherwise isolated virtual routing tables under policy control.
Purpose and use
Route leaking intentionally shares selected routes between normally separate VRFs, for example to reach a shared service.
How does it work?
Import and export can use BGP policy, route targets or device-specific local mechanisms.
Example and verification
For a shared service, verify import of the intended prefix into the correct VRF and an appropriate return route.
Points to watch
An overly broad imported route can expose unintended networks. Overlapping addresses and traffic filtering also require consideration.
In short
A shared route makes a path available; security policy must still determine which exchanges are authorized.