Stacked optical module cage with improved airflow to bottom ports

A housing with improved airflow, comprising:

• a cage dimensioned to hold a plurality of modules side-by-side in a lower compartment and a further plurality of modules side-by-side in an upper compartment;
• the cage having a middle compartment between the lower compartment and the upper compartment, with a heatsink in the middle compartment in thermal contact with the plurality of modules when the plurality of modules are in the lower compartment;
• the middle compartment ventilated through a first one or more apertures in each of two or more exterior walls of the cage;
• and
• the middle compartment to be further ventilated, when the upper compartment is unoccupied, through a second one or more apertures in an interior wall of the cage separating the middle compartment and the upper compartment, wherein the further two modules when occupying the upper compartment obstruct the second one or more apertures.

A method of ventilating a module cage, comprising:

• inserting a module in a second compartment of a module cage, so that the module makes thermal contact with a heatsink in a middle compartment of the module cage, and a first compartment of the module cage that is dimensioned for at least one module is unoccupied;
• ventilating the middle compartment and the heatsink therein through a first one or more apertures in two or more exterior walls of the module cage;
• and
• further ventilating the middle compartment and the heatsink therein through the first compartment and through a second one or more apertures in a wall separating the first compartment and the middle compartment.