Hello; I work with FEC in various ways, mostly to protect video streams against packet loss, including as co-chair of the IETF FECFRAME WG and in the Video Services Forum. Most FEC is driven by congestion in the edge, RF issues on wireless LANs, etc., but there is always the chance of loss in transit over the wider network. In many important cases, in fact, (e.g., transfer of video from a content creator to an IPTV service provider or Enterprise to Enterprise video conferencing) the loss at the edges can be controlled, leaving only network transit to worry about. This question has thus come up from time to time, and I was hoping that the assembled NANOG might be able to either answer it or provide pointers to the literature : What level of packet loss would trigger response from network operators ? How bad does a sustained packet loss need to be before it is viewed as a problem to be fixed ? Conversely, what is a typical packet loss fraction during periods of good network performance ? If there is some consensus around this, it would effectively set an upper bound for the need for FEC in network transit. I would be glad to accept replies in confidence off list if people don't want their networks to be identified. (To be clear, I am aware that many ISPs offer some sort of MPLS service with a packet loss SLA for video carriage. I am really asking about Internet transport here, although I would be pleased to learn of MPLS statistics if anyone wants to provide them.) Regards Marshall Eubanks