A data communications system includes optic adaptors that provide an interface between multiple line card chassis and a fabric card chassis. Optic adaptors can be added to the system to allow the addition of a number of line card chassis, thereby increasing the overall bandwidth of the system. The optic adaptors can also be separated from the fabric card chassis and line card chassis and upgraded to allow an increase in the overall bandwidth of the system. For example, optic adaptors that provide optical connections between a first number of line card chassis and the fabric card chassis can be detached from both the fabric card chassis and the respective line card chassis. Optic adaptors that provide optical connections between the fabric card chassis and a second, increased number of line card chassis are then installed within the fabric card chassis thereby allowing the additional line card chassis to be connected to the fabric card chassis.