Forward Erasure Correction (FEC) and network performance

Fri Apr 10 15:03:12 UTC 2009

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