  Dampers are devices that reduce delay jitter in the context of time-sensitive
networks, by delaying packets for the amount written in packet headers. Jitter
reduction is required by some real-time applications; beyond this, dampers have
the potential to solve the burstiness cascade problem of deterministic networks
in a scalable way, as they can be stateless. Dampers exist in several variants:
some apply only to earliest-deadline-first schedulers, whereas others can be
associated with any packet schedulers; some enforce FIFO ordering whereas some
others do not. Existing analyses of dampers are specific to some
implementations and some network configurations; also, they assume ideal,
non-realistic clocks. In this paper, we provide a taxonomy of all existing
dampers in general network settings and analyze their timing properties in
presence of non-ideal clocks. In particular, we give formulas for computing
residual jitter bounds of networks with dampers of any kind. We show that
non-FIFO dampers may cause reordering due to clock non-idealities and that the
combination of FIFO dampers with non-FIFO network elements may very negatively
affect the performance bounds. Our results can be used to analyze timing
properties and burstiness increase in any time-sensitive network, as we
illustrate on an industrial case-study.
