Review the PE router configuration to verify that split horizon is enabled. By default, Juniper devices configured as PE routers and VPLS enforce split horizon operation. Except for H-VPLS, Juniper devices do not support disabling split horizon operation. LDP signaled VPLS requires a full mesh topology, which can lead to scaling issues. Hierarchical VPLS (H-VPLS) partitions the VPLS domains into mesh groups, reducing the required number of pseudo wires. However, the inner VPLS domain may require split horizon be disabled. Juniper devices support these scenarios with the "local-switching" command. Ensure mesh groups supporting H-VPLS do not have the "local-switching" directive enabled, unless required, as shown in the following example. Generally, only inner mesh groups (that is, a group "nested" within another) may require split horizon be disabled. [edit routing-instances <name> protocols vpls] mesh-group <name> { : local-switching; : } Note: Only EX9200-series devices currently support VPLS. If split horizon is disabled but not required to be, this is a finding. Note: In a ring VPLS, split horizon is disabled so that a PE router can forward a packet received from one pseudowire to another pseudowire. To prevent the consequential loop, at least one span in the ring would not have a pseudowire for any given VPLS instance.