  The conversational quality of voice over IP (VoIP) depends on packet-loss
rates, burstiness of packet loss, and delays (or latencies). The benefits for
conversational voice quality of erasure coding attributable to its reduction in
packet loss rates are widely appreciated. When block erasure coding is used,
our analysis shows how those benefits are reduced or even eliminated by
increases in delays and in a measure of burstiness of packet loss. We
nevertheless show that the net effect of those three factors is still positive
over a wide range of network loss rates provided that block sizes are
sufficiently small and the sizes of decoding buffers have been optimized for
real-time media. To perform this analysis, we develop a new analytical model
describing the effects of block erasure coding on end-to-end network
performance.
