Why FEC Alone Won't Do!

Forward error correction is beginning to get some votes on the ipmulticast.com poll, but FEC alone can't give us Reliable IP Multicast. There are several reasons for this:

· Latency - FEC or spread spectrum FEC is going to increase latency during channel changes.

· Conspicuous consumption - In order to support a Radio LAN you have to send a LOT of FEC. Like 10 times the data in a noisy situation. In a radio LAN environment packet out-of-order and packet loss drive consumption beyond acceptable levels.

· Packet loss again - Yup', when your in a noisy environment, there aint' no' formula that accomplishes a perfect data transfer. There will always be a significant chance that the same redundant data will be lost multiple times.

· If one dynamically scales FEC (as some have proposed) then a congested network will signal to send more FEC and hence a more congested network. Unless we do something as lame a stepping down to the lowest receiver in the network.

So keep those thinking hats on because we aren't quite there yet!

Sorry but FEC alone won't do!