In an Active/Standby scenario for EVPN-MPLS E-LAN services, the customer reports about ~1-2 seconds of service distribution when they failover/restore the attachment circuit from the Designated forwarder (DF) to the Backup forwarder (non-DF)

The customer configured A/S EVPN-MPLS E-LAN services and when they brought down the attachment circuit from the active Designated Forwarder and we failover to the Backup forwarder, they observed traffic distributions 

in the remote PE site, we don't have the Type-2 routes pointing to the Backup forwarder ready and installed in the forwarding plane, and depending on the convergence time we might see traffic drops.

Similarly, traffic is expected to drop for a short period in the restoration of the attachment circuit as we need to move traffic now DF due to preemptive/revertive of DF role

by default service distribution in A/S EVPN-MPLS E-LAN services when the attachment circuit comes up/down is expected