An apparatus comprising: a plurality of ingress wavelength-selective switches, each having a respective input port and a respective set of output ports; a plurality of egress wavelength-selective switches, each having a respective output port and a respective set of input ports; and an interconnect device configured to optically connect the output ports of the ingress wavelength-selective switches and the input ports of the egress wavelength-selective switches using optical waveguides; and wherein, for at least some pairs of the ingress and egress wavelength-selective switches optically connected through the optical waveguides, the interconnect device is configured to: a) optically connect one of the output ports of a respective ingress wavelength-selective switch to one of the input ports of a respective egress wavelength-selective switch; and optically connect a different one of the output ports of the respective ingress wavelength-selective switch to said one of the input ports, or b) optically connect one of the output ports of a respective ingress wavelength-selective switch to one of the input ports of a respective egress wavelength-selective switch and optically connect a different one of the output ports of the respective ingress wavelength-selective switch to a different one of the input ports of the respective egress wavelength-selective switch. a plurality of ingress wavelength-selective switches, each having a respective input port and a respective set of output ports; a plurality of egress wavelength-selective switches, each having a respective output port and a respective set of input ports; and an interconnect device configured to optically connect the output ports of the ingress wavelength-selective switches and the input ports of the egress wavelength-selective switches using optical waveguides; and wherein, for at least some pairs of the ingress and egress wavelength-selective switches optically connected through the optical waveguides, the interconnect device is configured to: a) optically connect one of the output ports of a respective ingress wavelength-selective switch to one of the input ports of a respective egress wavelength-selective switch; and optically connect a different one of the output ports of the respective ingress wavelength-selective switch to said one of the input ports, or b) optically connect one of the output ports of a respective ingress wavelength-selective switch to one of the input ports of a respective egress wavelength-selective switch and optically connect a different one of the output ports of the respective ingress wavelength-selective switch to a different one of the input ports of the respective egress wavelength-selective switch. a) optically connect one of the output ports of a respective ingress wavelength-selective switch to one of the input ports of a respective egress wavelength-selective switch; and optically connect a different one of the output ports of the respective ingress wavelength-selective switch to said one of the input ports, or b) optically connect one of the output ports of a respective ingress wavelength-selective switch to one of the input ports of a respective egress wavelength-selective switch and optically connect a different one of the output ports of the respective ingress wavelength-selective switch to a different one of the input ports of the respective egress wavelength-selective switch.