In MP-BGP scenarios, with the following configuration:
set protocols bgp group <name> family inet-vpn unicast loops <N>
The BGP routes received from the core get installed in the VRF even if they contains the AS number defined in the VRF routing-instance more than <N> times.
Without the "loops" knob, the routes in the VRF would be hidden if they contain more than one occurrence of the AS number defined in the VRF under "routing-instances <name> routing-options autonomous-system <as_number>"
The hidden reason in "show route table <VRF.inet> <prefix> hidden extensive" shows as this:
Hidden reason: AS path loop
When "loops <N>" is configured under BGP protocol, such as this:
The routes are unhidden, and this loop prevention mechanism does not seem to work anymore, even if the received BGP route contains the AS number more than N times.
This behavior is as expected in the current implementation.
The "loops <N>" knob is actually working but compares the received AS-PATH with the AS number under the master instance (where MP BGP is defined)
This master instance AS number might be different from the AS number configured for the VRF.
If the received route contain the master instance AS number more than N times, it will be hidden