The constraint-rt-filter enable command enables an Route Target (RT) filter to filter Virtual Private Network version 4 (VPNv4) and Virtual Private Network version 6 (VPNv6) routes.
The constraint-rt-filter disable command disables an RT filter.
The undo constraint-rt-filter command restores the default configuration.
By default, an RT filter is enabled.
After an RT filter is enabled in the VPN-Target address family view, BGP filters VPNv4 and VPNv6 routes based on the import RT (IRT) of the peer. After the RT filter is disabled, BGP does not filter VPNv4 and VPNv6 routes based on the IRT of the peer.
If there is an Router Reflector (RR), only the routes in the VPN-Target address family need to be forwarded. In this case, no RT filter is needed. Therefore, you can disable the RT filter to ease the burden on the RR, therefore speeding up VPN route convergence.