How can a consistent QoS policy be applied across the master and backup BNGs for downstream traffic flows?

The QoS policy is automatically synchronized between the two BNGs. 

QoS policy synchronization must be configured under SRRP on both BNGs. 

By redirecting the downstream traffic from the backup to the master BNG via the shunt interface, 

By load-sharing the downstream traffic across the master and backup BNG.