In general, this disclosure describes techniques that may allow multiple spanning tree networks to be joined across a ring network. In a ring topology, e.g., an Ethernet ring topology, there are multiple nodes connected one to another to form a ring. Subtending from the ring network are customer devices that may joined together to form networks, e.g., Ethernet networks. Providing only a single connection between a subtending network and the ring network risks isolating the subtending network from the ring network if a fault occurs on the connecting link. Providing two links between a subtending network and the ring network, however, may create an undesirable traffic loop. One example protocol used by the customer devices to communicate with one another in a network and prevent looping paths is Spanning Tree Protocol.