[Udpcast] udpcast scalability?

George Coulouris coulouri at ncbi.nlm.nih.gov
Wed Feb 23 18:53:07 CET 2005


I've managed to get reliable transfers to all 85 machines at this point 
(bad nic in the sender, I think).

I'm still bottlenecking at 45Mbit or so, though, despite the fact that 
all machines are on switched copper gigabit.

If fec is turned on (either 8x8/128 or 16x4/128), receivers disconnect 
throughout the transfer until only ~10 remain at the end.

If fec is turned off, I get high retransmission rates (15-25%), but the 
transfer at least succeeds to all hosts. Again, I'm sending about 20G of 
data, which should take about an hour at 45Mbit. In practice, it takes 
about an hour and a half, and sometimes close to two hours.

For simple point-to-point tests with udpcast (between 1 and 5 
receivers), I can achieve higher bandwidths reliably (sending 128 
megabytes at 80mbit), both with and without fec.

It sounds like my issue is similar to Ramon Bastiaan's:
http://lll.lgl.lu/pipermail/udpcast/2004-September/000298.html

Ramon, have you had any luck?



More information about the Udpcast mailing list