nanog mailing list archives
Re: Forward Erasure Correction (FEC) and network performance
From: Matthew Kaufman <matthew () eeph com>
Date: Fri, 10 Apr 2009 10:43:26 -0700
Marshall Eubanks wrote:
If there is some consensus around this, it would effectively set an upper bound for the need for FEC in network transit.
The bit error rate of copper is better than 1 error in 10^9 bits. The bit error rate of fiber is better than 1 error in 10^12 bits. So the packet loss rate of the transport media is approximately zero.*
Thus any packet loss you see is congestion. If you see packet loss, you should SLOW DOWN, not just keep sending and using more and more FEC to get recoverable video out the far end. (And by "SLOW DOWN" I mean in a way that is TCP-friendly, as anything less will starve out TCP flows unfairly and anything more will itself find that it is starved out by TCP)
Matthew Kaufman* The bit error rate of RF-based connections like Wi-Fi is higher *but* because they need to transport TCP, and TCP interprets loss as congestion, they implement link-level ARQ in order to emulate the bit-error-rate performance of wire as best they can.
Current thread:
- Forward Erasure Correction (FEC) and network performance Marshall Eubanks (Apr 10)
- Re: Forward Erasure Correction (FEC) and network performance Patrick W. Gilmore (Apr 10)
- Re: Forward Erasure Correction (FEC) and network performance Mikael Abrahamsson (Apr 10)
- [SPAM] Re: Forward Erasure Correction (FEC) and network performance Jean-Michel Planche (Apr 10)
- Re: Forward Erasure Correction (FEC) and network performance Matthew Kaufman (Apr 10)
- Re: Forward Erasure Correction (FEC) and network performance Lamar Owen (Apr 10)
- Re: Forward Erasure Correction (FEC) and network performance Matthew Kaufman (Apr 10)
- Re: Forward Erasure Correction (FEC) and network performance Mikael Abrahamsson (Apr 10)
- Re: Forward Erasure Correction (FEC) and network performance Lamar Owen (Apr 10)