On Mar 7, 2006, at 3:57 PM, Mark Hahn wrote:
effective in some cases. However, the bulk file transfer rates for
very large files via FireWire 400 (1394a) is significantly faster
than 1000baseT and FireWire 800 (1394b) is more than 240% faster
that GigaBit EtherNet.
can you show some references for this? it's hard to understand why
a 400 Mbps connection would be "sigificantly faster" than a 1000 Mbps
connection. or are you talking mainly about shortcomings in some
platform's drivers/stack?
Easiest, simplest reference is this image: http://unibrain.com/
products/assets/FireNET5.jpg ... or read the whole report at bottom
of: http://unibrain.com/products/driverapi/firenet.htm
Note that for large files, the FireWire network bulk file transfer
rates can exceed GigaBit performance. The above reports (arguably
promotional) are for FireWire 1394a (400 Mbits / second). When
similar tests are run on FireWire 1394b (800 Mbits / second),
performance can exceed 240% of network bulk file transfer (write
times) of GigaBit EtherNet.
Why is it comparable to or faster from a processor running at around
40% of GigaBit processor speeds? Processor efficiency FireWire has a
32-bit "risc" type microprocessor, is peer to peer in hardware /
firmware and has other lean architecture features. (Small address
space, data frame large = more efficient data packet over double
duplex connections.)
A down side?: FireWire 1394a (now called FireWire 400) has an address
space of maximum 64 nodes, maximum and optimally less than 32 nodes
(less than 16 recommended). FireWire 1394b (now called FireWire 800)
can address a maximum of 128 nodes, but because of the nature of the
topography ("quad duplex" or double, double duplex, twice as many
connections at same processor speed), optimum performance is still
achieved from less than 32 nodes.
Future: there are prototypes of FireWire 1600 and 3200 operating over
fiber and using multiple "colors" ... using two fibers (duplex),
multiplexed by frequency discrimination (4 or 8 channels) using the
same FireWire 800 (Texas Instruments chips) ... comparable to ~~
64000baseT ... and the involved engineers say they can stay ahead of
Moore's Law beyond several more years.
Ed Karns
FireWireStuff.com
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