In Matrix Reloaded, what are the 'traffic control' people connected to?

It relates to the training areas of the first movie.

If you recall, the ships are there in order to broadcast a 'hacker signal' into the Matrix in order to get their people inside it. This requires them to travel a great distance away from Zion. From this we can deduce that this is not the Matrix.

Further, recall that where they trained Neo (and themselves, for that matter) is essentially a Local-only (LAN only) version of the Matrix where they could create whatever they pleased (called The Construct).

This area that these 'Gatekeepers' appear to be plugged into is a similar Construct. It gives them computers and a database and all other kinds of control over the gates and who does/does not have access to Zion.

As far as meaning and how much work it requires, I cannot say that this all seems practical, nor does it seem likely that they should be doing this, but such is the way of this series.