Be aware of the effects triggered by specific 'failure scenarios'; some of these scenarios are shown in Figure 1:
If an individual VPLS service is shutdown in PE1 (the example is also valid for PE2), the corresponding LAG SAP goes operationally down. This event triggers the withdrawal of the AD per-EVI route for that particular SAP. PE3 removes PE1 of its list of aliased next-hops and PE2 takes over as DF (if it was not the DF already). However, this does not prevent the network from black-holing the traffic that CE2 'hashes' to the link to PE1. Traffic sent from CE2 to PE2 or traffic from the rest of the CEs to CE2 is not affected, so this situation is not easily detected on the CE.
The same result occurs if the ES SAP is administratively shutdown instead of the service.