We have an office building need to be connected to the corporate network, the available switches are 6800ia-48fpd and the parent switch at the data center is 6880-x-le. The 6880ia uplink is connected through dark fiber link to the parent switch, we need to connect another redundant link in case the fiber failed, can we connect through an MPLS link or layer 2 transparent link through Huawei RTN 310?