Requirements and Limitations
  
    The solution shown in VPLS EAPS Redundancy Overview
      has the following requirements and limitations:
    
      - The redundant VPLS nodes must be core nodes.
- An EAPS common link is required between the
        redundant VPLS nodes.
- The redundant VPLS nodes (Core 1 and Core 2) use PWs to connect to
        each other and the other core nodes (Core 3 and Core 4).
- The redundant VPLS nodes use PWs to support the EAPS-protected VLANs,
        not the EAPS common link.
- Works only with EAPS customer attachment ring.
- The EAPS master should not be on a
        VPLS node.
- EAPS state used by VPLS to control state of PWs (Active/Ready).
- EAPS monitors common link state and ring state.
- VPLS on controller node uses EAPS state to set Active/Ready PWs.
- EAPS blocks customer-facing ports as normal.