Communication systems having pluggable modules

A system comprising:

• a housing for a rackmount server having a front panel;
• a first substrate that is positioned at a distance from the front panel, in which a data processor is mounted on the first substrate, wherein the first substrate is spaced apart from the front panel at a distance less than 12 inches, and the first substrate has a main surface that is oriented at an angle in a range of 0 to 45 degrees relative to the front panel;
• and
• a pluggable module comprising an optical module, at least one first optical connector, a first fiber optic cable that is optically coupled between the optical module and the first optical connector, wherein the pluggable module has a bandwidth of at least 10 gigabits per second;
• wherein the optical module is configured to receive optical signals from the first optical connector and generate electrical signals based on the received optical signals, and the electrical signals or processed versions of the electrical signals are transmitted to the data processor;
• wherein the pluggable module has a shape that enables the pluggable module to pass through an opening in the front panel to enable the optical module to be coupled to the first substrate;
• and
• wherein the data processor is capable of processing data at a rate of at least 100 gigabits per second.