Force NIC to 100 Mbps

I have a desktop computer that's a few years old, I ressurected it just there a few days ago. The NIC in it is the "3Com EtherLink III ISAPNP", also known as the 3Com 3c509b, which is about a decade old at this stage.

The card is capable of both 10 Mbps and 100 Mbps. The card was designed in the period when 100 Mbps was being phased in and so while it *can* work at 100 Mbps, it defaults to 10 Mbps when it checks the line (irrespective of whether other hosts on the collision domain are working at 100 Mbps).

I have a boot disk for the card which lets me set its settings (e.g. I can set it to work in Full Duplex), but it doesn't let me choose whether to use 10 Mbps or 100 Mbps.

Does anyone know of a way of forcing a NIC to 100 Mbps? Or does anyone have experience with this particular card and know a way of getting it to work at 100 Mbps? I'm working with Windows XP Pro SP2.

Thanks for reading

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Tomás Ó hÉilidhe
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Is it? The 3c515 is, but the 3c509 and 3c509B are not. The 3c905 of course is, but that is a PCI card. Mind that you will have a hard time getting any serious throughput on an ISA bus, so there is not much point in trying to force the issue.

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jpd wrote in comp.dcom.lans.ethernet:

Wups I must have gotten it wrong... I was almost certain I saw "10/100" written somewhere.

I was looking at NIC's on eBay just there and it seems you can get a 100 Mbps card for less than $5 :-O

I also see that there's these little USB connectors that are basically a really really small NIC:

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Are these any use? I have USB 2.0 slots in my PC but they're on a card that connects via PCI... so I'd probably be better off cutting out the middle-man and getting a NIC that connects directly to PCI? Then again it would be hand having a tiny little NIC I can carry around and stick into computers via USB :-D

What brand should I look for on eBay when buying a PCI NIC? There's a few Realtek cards for less than $5. I've a gigabit Realtek NIC in my laptop and I've had no trouble with it. (But then again I've never gotten a chance to use it at 1 gig ha). Should I go with Realtek? Or is there a PCI 100 Mbps NIC out there that's head and shoulders above the rest? (and which I can still get for about $5 on eBay :-D).

The main throughput I'll need will be for Samba file-sharing, basically copying a few gigabytes to the desktop machine when I'm backing stuff up. Do you think a 100 Mbps PCI would be a vast improvement over the 10 Mbps ISA, or are there other bottlenecks which decrease the difference? The machine with the Samba share is a Pentium III 500 MHz with a pretty fast hard disk.

And last but not least, would it be pointless to connect a gigabit NIC into a PCI slot?

Thanks for your help jpd, and thanks for those links too.

Reply to
Tomás Ó hÉilidhe

You can get them new for that, or almost that. Those tend to be realtek cards, and you do get what you pay for. They're fine if all you want to do is drive a 2Mbit adsl modem, or have otherwise low to moderate needs and CPU to spare. I still wouldn't want them in my systems.

I have little experience with how well USB NICs perform. They are indeed useful if you have an USB slot and quickly need to link up something. If you can put in a PCI card, that'd be my first choice, if for no other reason than that it's one less dangly thing sticking out that might get knocked off or get lost or whatever.

Looking at that link, I notice ``Full-speed (12Mbps) usb device''. I don't know whether the USB 2.0 mentioned elsewhere in there means it'll go even faster on the USB side if USB 2.0 is available, but if it doesn't, it won't be able to keep up with a fast ethernet PCI NIC.

My preference goes out to digital-now-intel[1] 21143 (`tulip') cards, and the intel pro 10/100 (8255x and 8256x) cards, 3com 905c after that, then the rest, and way way way after that, anything realtek or its clones(!). For a server 3com 980 is also an option because its hardware does checksum offloading, but you won't notice gains from that in casual use, just like most people don't notice the low realtek performance.

That's all about 10/100 cards. If you can find a GigE card cheap and it isn't realtek I'd probably go for it (eg intel, broadcom, syskonnect). I have to say I'm not up to speed on relative GigE NIC performance so maybe someone else can chip in with experience there.

Another way to increase performance is to reduce the traffic needs. Specialised backup software can reduce the amount of data that needs to be transferred. Or moving the tapedrive or getting an extra dvd burner might be options as well. It's all in how you organize things.

I can't tell from here where there are additional bottlenecks, if any. If that machine is the slower of the two, check that it too has a reasonably fast NIC, and not a realtek. If it has an ISA 10Mbit card, you won't see gains. If the disk is fast in theory but the disk controller is not, you won't see gains either. And so on and so forth.

For example, someone complained his two fast machines with a good quality NIC each didn't get the full performance out of the shared internet link. Turned out the router/firewall/gateway was an old leftover box with two realtek cards in it. In that case, moving the realteks to the newer machines and putting the better cards in the gateway saw satisfactory improvements for little effort and no cost.

And then there's the network infrastructure to condsider. If you have an old 10Mbit hub to tie it all together, no amount of GigE NICs is going to help you, unless and until you also get a GigE switch.

That depends a bit on your traffic patterns. For example, GigE NICs driving a 100Mbit link can outperform fast ethernet NICs if the traffic consists of mostly small packets.

You probably will see some gains, especially if both the disk controller and NIC are on 64bit and/or 66MHz PCI. Whether it will likely be worth it someone else can say better than I can, altough that someone would probably need more detailed information as well. Whether it'll be worth it to you is something else again.

[1] The design is by digital, but intel acquired the plans and sold them under its brand for a while too.
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