Possible gigabit network

I presently have a very small network consisting of 2 PCs with onboard 10/100 NICs, and a Linksys 5 port 10/100 switch.
I have two gigabit PCI LAN cards (one for each PC) and all I have to do is buy a gigabit switch (looking at the D-Link DGS-2205).
I plan on disabling the onboard NICs.
My questions are:
Do gigabit PCI LAN cards have limitations because of the PCI bus?
Is it worth the upgrade?

Thanks for your help

ok, well PCI 2.1 32bit has a throughput of 266MB/sec, and Giagabit ethernet can, without any overhead loss calculations, do 125MB/sec. So you wouldn't be limited by ur bus,. A to wherther its worth the upgrade or not, well ti all depends on how much u want ur speed, do you transfer lots of large files over your network? if money isn't an object then I'd go for it.

Nick

I do transfer large files quite often. My wife is paranoid about the data on here D: drive so I image it once a week and transfer the image to my PC (I have a terabyte so I have the room). Running a gigabit network should speed up that transfer.
Thanks for your input. I was just wondering if using PCI based gigabit cards would be better than the onboard 10/100 NIC.

Thanks,
Quick

You are going to be hard drive limited actually as no single HDD can handle a 125MB/sec read or write speed.

so even if i get a sataII hdd that can get 300 mbps (or so they say), the darive still won't be able to keep up?

ah life is but a lie!!!

300mbps brust / max speeds thats all my friend =(.

you will also be limited by the packet size and file size. generally transferring small <10MB files will be slower to transfer than huge 100-200MB rared files. (hence HDD)

secondstage said:

so even if i get a sataII hdd that can get 300 mbps (or so they say), the darive still won't be able to keep up?

ah life is but a lie!!!

Click to expand...

In a single drive configuration you'll see 60-100MB/s sustained speeds, the new Seagate 7200.11's are a little higher, I've seen slightly over 100MB/s.

Back on topic, are you doing the copying manually? You could always have a scheduled backup at some point when the computers are not in use then the transfer time won't really matter. However ff you already have the cards though, I'd just get the switch and do it.

Quick69GTO said:

Do gigabit PCI LAN cards have limitations because of the PCI bus?
Is it worth the upgrade?

Click to expand...

Yes, PCI has an impact on the maximum performance of gigabit NICs, for a couple of reasons. (1) Standard PCI bandwidth is very close to maximum single-duplex gigabit bandwidth, and gigabit is full-duplex. (2) PCI overhead reduces overall performance. However, (*) even with this impact, a GbE NIC is much faster than a 100 Mb/s NIC.

PCI will of course have the biggest negative impact when you have (a) other high-bandwidth applications being used at the same time as the NIC on the same PCI bus (e.g. storage controller, old video adapter), (b) when you have a poorly-implemented PCI bus (e.g. some old VIA chipsets, among others). However, point (*) still holds.

But what's "much faster"? IMO, 2-3x faster than ideal 100 Mb/s is "much faster", and this is a reasonable goal for large file transfers over gigabit on typical configurations, OSs, etc.

Going much faster can be done, but that can be difficult and non-intuitive, and require some tuning, together with obvious requirements such as fast hardware including fast disk subsystems on both ends.

You can test performance impact without buying a new switch, by directly connecting the two machines with a LAN cable and refreshing the IPs, etc. Gigabit in general supports auto-crossover, so crossover cables aren't needed.

Thank you all for your responses.
Imaging her D: drive is probably not the correct term. I just copy the contents over to my PC.
Madwand, I actually already have a crossover cable so I could set it up that way instead of buying a switch. Using a crossover setup will also keep me from hogging network bandwidth so I can surf the web while still transferring files.
That's freakin' brilliant, I just saved myself $50.
By the way, I've done a crossover before when I ran multiple PCs at my desk (KVM) so I know how to do it.
I can't believe I didn't think of it before I posted my questions.

Have fun!

Watch out for Windows' routing screwing up. I've never been able to get windows to enjoy having 2 nics on 2 different networks and able to access both networks, even by manipulating the routing tables.

I went ahead and bought a gigabit switch and ditched the dual NIC idea. I have setup 2 NICs/ 2 networks before and it worked flawlessly but I decided to pop for the switch instead.
I haven't transfered any files yet but I can say my internet seems a little more snappier.

Thank you all for your input.

~(o)-(0)~ said:

ok, well PCI 2.1 32bit has a throughput of 266MB/sec, ....

Nick

Click to expand...

32bit*33Mhz = 1056 Mbs-1
1056/8 = 132 MBs-1 less overheads

aftermath said:

32bit*33Mhz = 1056 Mbs-1
1056/8 = 132 MBs-1 less overheads

Click to expand...

PCI 2.1 allows for 32bit 66MHz operation with compatible 3.3v cards. However, it's pretty rare to actually see this in the real world. Expect the standard 133MB/s for a given PCI desktop, since most boards were 5v up until PCI-e started taking over.

Anyway, I just wanted to mention a tweak from an article I ran across last night. My Vista x64 gigE performance has been rather lacking, so I did some digging about tuning the TCP stack. Turns out the default window size was too small and RFC 1323 are not on by default. Adding the two registry keys listed got me an additional 30% on iperf tests. Might do this in the office tomorrow on the 2003 machines.

Gigabit tuning (written for BSD, but with Windows tweaks as well).
Technet TCP Window Size reg key
Technet 1323 reg key

Cheator said:

Watch out for Windows' routing screwing up. I've never been able to get windows to enjoy having 2 nics on 2 different networks and able to access both networks, even by manipulating the routing tables.

Click to expand...

When i had to be in 2 networks @ qwork i changed the priorty under the advance options of the NIC, set one as 1 and the other as 2, both manually assigned IP's /subnet and gateways and i never had an issue.

Snugglebear said:

Anyway, I just wanted to mention a tweak from an article I ran across last night. My Vista x64 gigE performance has been rather lacking, so I did some digging about tuning the TCP stack. Turns out the default window size was too small and RFC 1323 are not on by default. Adding the two registry keys listed got me an additional 30% on iperf tests. Might do this in the office tomorrow on the 2003 machines.

Click to expand...

Those settings probably don't even apply to Vista, which uses auto-tuning.

If you're able to confirm this repeatedly, with a single set of changes going back and forth, documenting the details, I'd love to see them.

Vista's network and file transfer performance can certainly be variable, sometimes unpredictably due to the auto-tuningness (and bugs), but I've also seen great performance from it with default network settings.

vista network performance has been massively increased in SP1 i got the RC installed and network transfers are easily 3x faster it seems.

Madwand said:

Those settings probably don't even apply to Vista, which uses auto-tuning.

If you're able to confirm this repeatedly, with a single set of changes going back and forth, documenting the details, I'd love to see them.

Vista's network and file transfer performance can certainly be variable, sometimes unpredictably due to the auto-tuningness (and bugs), but I've also seen great performance from it with default network settings.

Click to expand...

It will take a while to undo all the changes over the past few months and retest/re-document, but I can certainly try. Need to check the managed switch, too. Utilizing jumbo frames was the best bang for the buck, but the TCP stack window reg hacks definitely sped things up significantly.

I was blown away by how bad the network performance in Vista has been compared to XP x64; comms between a 100Mbps BSD server and the dual-GigE vista box were running at, I kid you not, 60Mbps in iperf. Jumbo frames didn't do anything here, but the reg keys brought it up to 97Mbps, which is what I get from BSD box to BSD box. XP used to give me 85Mbps after install and before tuning; same hardware, big difference. And I won't even start on the more annoying things like high choke values in TF2... the one game I play and it cries uncle from all the UDP packets.

EDIT: Vista here is not SP1, just hotifxes ATM.