English: Time diagram of the operation an elastic buffer.

The delay (=phase) of the transitions in the incoming pulse stream is jittered with respect to then average transmission delay. The buffer adds a complementary delay so that the sum of the jitter delay plus the buffer delay are a constant amount at any time. The buffer depth (= the register length) is equal to the maximum peak-to-peak jitter expected (plus some margin). The delay added by the elastic buffer, in the time diagram, is a curve mirroring vertically the jitter (=delay) of the transitions of the incoming pulse stream.

The mirror is located at a delay equal to the average transit delay (plus some little margin).