> Now if we're using STP on this, will it benefit from the firmware in the
> GBit master or not? If STP is wrapped in TCP on the 100 MBit side it
> probably wouldn't, but if it creates real STP packets it might.
Hi
The modified firmware only benefits receives, although STP on Linux
also does zero-copy transmits with some driver changes, which help
a bit. You can get the same for TCP too these days, and I will probably
change STP to use the same infrastructure as there's now a
"stable" release of it out at
ftp://ftp.kernel.org/pub/linux/kernel/people/davem/.
>
> Any comments on this situation? Has anybody tried something similar, with
> what results? We need to broadcast data from the master and collect data
> from all the clients quickly, and STP seems like a good idea to reduce
> overhead and latency.
If you're sending the same data to all of the clients, and there's
a lot of them some kind of reliable multicast protocol might be a good
idea (latency might be a problem with these, though), I haven't followed
this area recently, though.
Otherwise STP might do the job, although without hardware assist it won't
perform that much better than TCP as far as CPU use and bandwidth are
concerned (especially on 100baseT, which is slow enough that modern
machines have no problems dealing with it).
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