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Does it matter what gigabit ethernet card you get?

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MRD

Senior Member
Joined
Feb 14, 2003
Is there a noticeable difference in throughput depending on which card you get? I've read a lot of reviews where people are complaining about getting 20-30 MB/s on gigabit ethernet.

Also, how much does it matter if you are pci or pci-e?

In theory, PCI is 133 MB/s (the whole PCI bus, so it's shared)
PCI-E x1 is 250 MB/s (per channel)
Gigabit ethernet is 125 MB/s
Very fast disk drive is about 120 MB/s (which is < all SATA and < ATA133)

I am wondering if I should just buy the cheapest card or if getting higher end stuff will yield faster throughput. Anyone have any experiences with this?
 
While there are measurable differences, for the most part, with a typical random setup, you're right -- it doesn't really matter. When you're transferring files at around 40 MB/s, which is very common, it's not likely that the NIC is the bottleneck. It could be the system's PCI implementation in some rare cases, but otherwise it's much more likely to be a combination of the OS and its file transfer protocol together with the hard drive / file system performance on both ends.

Combining a PCI NIC with a PCI storage controller or a PCI video card would of course lead to significant performance bottlenecks due to bus crowding, but it can still be much better than 100 Mb/s networking.

If you have high performance drives or RAID arrays on both ends, a recent OS, and a lot of luck, then you can approach gigabit saturation, and in this case, the details of the NIC and bus matter.
 
I know my MoBo's onboard NIC's can sustain over 100MB/s through a cheap Linksys 8-port switch - and I know they aren't using uber-expensive chips in those (P5B-E for example - the entire MoBo was like $80). My RAID arrays are a different matter all together ;)

That's my experience, but I'm sure there are reasons to spend cash and get the higher priced $50 PCIe GigE NICs.

I'd assume you should avoid PCI NICs if you want a good Gigabit experience. GigE can almost cap-out the entire PCI bus. My MoBo's use PCIe on-board NIC's and I think that is what makes a difference (and FAST HD's/RAID Arrays :p )...

:cool:
 
The more expensive cards have a little more logic circuitry to process the transaction. Which might help with latency and possibly bandwidth. The biggest killer of bandwidth speeds would be an active file scanner. In the case of a Linux user. You don't notice it as much. Since less system bandwidth is wasted to process the file as it comes in.

Unless your going to be really on the huge sustained transfers. You might do fine with a cheap Realtek based card. Similar to what Randy mentioned, You could clog up the PCI bus. If the bus is needed for other things during the transaction.
 
I move a lot of big files around the network relatively frequently... and the 100 mbit is becoming too slow for me. Some of my comps do not support pci-e. (The router doesn't either but that shouldn't matter since it's basically just a gateway to the internet... even if I'm moving blue -> green or vice versa, that's limited by wireless speeds and that's well under 100mbit.0

I am going to need ~10-12 gigabit cards, so obviously, I don't want to spend more than I have to. I also need a 16 port gigabit switch and a 4 port gigabit switch. What do I look for in a card to know if it's going to be faster? And is it even worth it on the PC's that are limited to PCI?

Are on board gig-eth adapters usually connected through the pci-e bus or the pci bus?
 
I am going to need ~10-12 gigabit cards, so obviously, I don't want to spend more than I have to.

Shop around then, there are great variations in prices. You should consider the underlying chipset more so than the brand name, and digging that up often just means looking closely at the picture, and sometimes downloading the driver and examining it.

In gigabit, there are a limited number of chipset providers. E.g. Intel, Marvell, Realtek, VIA, and Broadcom. Intel are generally considered the best, and also tend to be the most expensive. You can however sometimes find good deals for used Intel NICs on eBay -- typically old server pulls. Of course, you'd have to be careful with eBay purchases, research the particular device (avoid fibre NICs look for current driver support), and be willing to take some risk.

If you take a "I want quality, and I'm willing to pay for it", Intel is an easy answer.

If you take a "I want gigabit at the lowest cost possible", then you're probably looking at VIA or Realtek chipsets unless you luck out on eBay. I have no experience with VIA NICs, but Realtek has passable driver support and performance, although at a relatively high CPU utilization. Marvell PCI is better on CPU utilization, but this comes with generally less throughput.

How much will this matter? Probably not that much. Getting to gigabit alone is the big step. Fine tuning gigabit for the best possible performance is generally an exercise in frustration as some non-trivial, hidden and uncontrollable factors come into play. (E.g. OS performance, PCI bus performance, composite of issues on both ends of the transfer.)

Are on board gig-eth adapters usually connected through the pci-e bus or the pci bus?

Both. Many still hack something on the PCI bus, many use a newer PCIe chip. Some have both. You can usually determine this from the model number of the chip, if the motherboard vendor doesn't tell you up-front or provide a system diagram with that information. Some motherboard vendors have even disabled or crippled a nice native NIC and hacked on a PCI-bridged one (e.g. Gigabyte has done this at times).

IMO, PCIe versions are generally worth pursuing when possible, not just for the bus issue, but also because sometimes the PCI versions are ancient creaking designs, and the PCIe versions perform better. Of course, this is also a simple generalization -- sometimes vendors have gone in the opposite direction, from older well-performing NICs to cheaper ones later with smaller feature sets and potentially less performance.

The good news is that all these details for the most part don't matter much for simple workstation usage -- the bottlenecks are elsewhere.
 
*anipped*Realtek has passable driver support and performance, although at a relatively high CPU utilization. Marvell PCI is better on CPU utilization, but this comes with generally less throughput.

This is passing the savings on to you concept. There is hardly any logic on the card or hardware. So it uses the host machine to do the work Keeping the part cheaper.
 
So in the case of the Intels, does it have a dedicated chip that functions something like a coprocessor, while the Realteks just use the cpu? i.e. Is it similar to the difference between an old Tseng Labs ET4000 VGA card and the early Diamond S3's that added the first common graphics coprocessors?

How much difference in throughput are we talking? If I jump from a Realtek to an Intel (assuming those are the worst and the best), do I go from 20MB/s to 21, or do I go from 20 to 90?
 
How much difference in throughput are we talking? If I jump from a Realtek to an Intel (assuming those are the worst and the best), do I go from 20MB/s to 21, or do I go from 20 to 90?

Much closer to the former than to the latter. Odds are that you'll be bottlenecked by factors other than the NIC, so this gigabit NIC vs. that gigabit NIC will have little impact overall on file transfers.

If you have really fast drives and a modern OS, then the impact could be greater because you'll be more limited by the NICs. If you have really a slow CPU, the impact could also be greater because one's bottlenecking on the CPU then.

In general, it's hard to be sure about any of this things based just on theory - practice doesn't match theory. You might want to get one of each, test them out, and then buy the rest afterwards.
 
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