Gigabit Ethernet + PCI: how fast/any suggestions?

ShyGuy91284 · Tux's lil' helper Joined: 28 Mar 2004 Posts: 114

I'm looking into getting a gigabit hub and a few gigabit cards for my hardware (I'm noticing when one computer acts as a file server for another one, the network can get extremely bogged down, and affect connections beyond the switch.). But I've heard of the PCI bus limiting how fast data can be transferred. Anyone have any experiences w/ gigabit networking? At what speed do files transfer over a PCI card in comparison do a built-in ethernet connection? And what gigabit PCI cards are compatible with linux? Thanx in advance.

nobspangle · Posted: Sat Oct 16, 2004 11:18 pm Post subject:

Don't have much experience with gigabit but I can tell you that an onboard gigabit controller will have exactly the same problems as a PCI card as it still runs through the PCI bus. The exeptions to this are boards with Intel's CSA bus, and boards with PCI buses faster than 32bit 33MHz.

However gigabit should solve your problems with network speed whilst large file transfers are occuring as the file transfers won't be capable of maxing out the connection speed as they will be limited by harddrives and PCI buses

NeddySeagoon · Posted: Sun Oct 17, 2004 12:08 am Post subject:

ShyGuy91284,

Heres some theory to think about. The max data rate over 32 bit 33MHz PCI bus is 233 Mb/sec. This is the absolute tops, given fast writes, bursts, etc.
If you are looking for sustained data rates, the data has to come from somewhere, lets say a disc. With IDE you may get 50Mb sustained from the platter (check with hdparm). Unfortunately, this 50Mb/sec has to pass over the PCI bus twice. Once from drive to memory and once from memoery to NIC, so thats 100Mb/sec on your PCI bus.
Other things want PCI bus bandwith too, so with a hdd maxed out you may get at most 480Mbit/sec.
Thats assuming that the network remains the bottleneck. It can only be worse than that when you add in handshake time for data than must trave the other way.
I don't think GB NICs on 32bit 33MHz PCI are worth the money.
The whole system needs to support the Gigabit data rate, not just the NICs
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Computer users fall into two groups:-
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r@mbo · Posted: Sun Oct 17, 2004 8:00 am Post subject:

wait till pci-express is a little more popular - that is when it is a good idea to get gigabit ethernet
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nobspangle · Posted: Sun Oct 17, 2004 8:42 pm Post subject:

fs_mariner · n00b Joined: 12 Jun 2004 Posts: 45

I have a gigabit network. Something to consider is that with most gigabit switches, they will slow down to the slowest connection speed. For example, my whole network slows down to 100 if just one 100 speed network card is plugged into the hub. So, I had to buy all 1000 speed cards for every computer including my gateway.
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