A silly PC conversion question

[NC1]

This is probably not OpenWrt-specific, but I’d like to solicit some opinions anyway…

Let’s say we are converting a one-liter PC to a dual-port router. To make it specific, let’s say that the built-in NIC is Intel i217 or i219. We are adding a split-design second NIC (the kind where one half sits in a Wi-Fi card slot, the other half is attached to the case wall, and there’s a cable connecting them). Again, to make it specific, let’s say that the add-on NIC is Intel i210.

Now, the question: is there any reason to prefer designating one of those NICs as LAN or WAN? Or are they completely interchangeable, so you can invert the assignment with no change in performance and functionality?

[brada4]

eth0 (lan) will be one found first enumerating pci bus. Multi-port cards, like second-hand 4x gbe are much better for space saving.

[slh]

Yes'ish.

Even PCIe v1 x1 can do 250 MByte/s, so 2 GBit/s, meaning it just fits.

Personally I would use the onboard card as lan, as that one might do V-Pro/ AMT and similar extra features (which might be useful to your lan, but not the internet). In terms of performance, PCIe v1 will do and anything higher will be comfortable.

[NC1]

@slh

Personally I would use the onboard card as lan, as that one might do V-Pro/ AMT and similar extra features (which might be useful to your lan, but not the internet).

This aligns with what I was thinking to myself when I posted the question, except my reasoning was a little cruder. The original manufacturer developed the PC for use as a client device (networking-wise), so if an onboard NIC has features that are more useful in one role as opposed to the other (LAN vs. WAN), those features are more likely to be “LAN-helpful” than “WAN-helpful”. So my rule to date has been, onboard NIC is LAN, add-on NIC is WAN…

Thank you for sharing!

[NC1]

@brada4

Multi-port cards, like second-hand 4x gbe are much better for space saving.

I understand that, but my question was about one-liter PCs (and, indirectly, thin clients), which typically have neither connectivity nor internal space to hold a multi-port NIC. There are exceptions, such as Lenovo M720q / M920q / M920x, or Dell Wyse Extended models, or HP Txxx Plus models, but they are indeed exceptions.

Speaking of thin clients, I just put together a router based on HP T630 (regular, not Plus). Came out kinda neat:

I expected more trouble fitting the NIC in, but the device cooperated; even mounting holes lined up (I took out the removable VGA connector and mounted the add-on NIC in its place). This one worked out to be all-Realtek (the onboard NIC is Realtek, so I figured, let’s put in another one to match)…

[_bernd]

Just as a side node: If Money ist not the issue and you are located in the DACH region, then I can recommend https://www.ipu-system.de/

[RangerZ]

@NC1 Would you detail the items you used in your build?

How is it working in practice?

Also you indicated that you used the WIFI slot, but a quick Google seems to indicate there are items that may also work in the m.2 drive slots. Is there a reason you went one way over they other?

[NC1]

@RangerZ

Would you detail the items you used in your build?

Which one? I’ve done dozens. Here’s one of the latest, which I reported to David at Parky Towers:

How people have modified their HP t630 thin client

But I’ve done similar mods on Lenovo M600 / M700 / M710q / M910q, Dell Wyse 5070 Standard, Dell Optiplex 7050, and I am probably forgetting a few…

How is it working in practice?

In practice, you have to pay attention to several things. The add-on NIC consists of three parts, (1) the part that goes into the Wi-Fi slot, (2) the part that attaches to the case wall, and (3) the connecting cable. Part (1) is not always regulation-size, it can be longer and/or wider than a Wi-Fi card. Here’s an example:

Note how the contacts in the back of the card extend beyond its dimensions. In some cases, this results in an unresolvable collision with other components.

Part (2) may or may not install easily (or at all) into an existing opening in the case. There’s some risk and experimentation involved. In some cases, you need a 3D-printed mounting bracket. In others, you need to carefully remove excess metal from the device’s case.

Finally, part (3) must be long enough to connect the first two parts in their respective locations. This one is rarely a problem on one-liter PCs or thin clients though…

a quick Google seems to indicate there are items that may also work in the m.2 drive slots

I am having a hard time thinking of a device in the one-liter / thin client universe where this were geometrically possible. Getting a networking device to work in a slot designated for storage device typically involves an adapter card, which makes the setup much thicker and can lead to all sorts of collisions. For example, Lenovo M710q / M910q actually have their NVMe drive slots on the bottom of the motherboard. There’s no way to run a ribbon cable from there into the case, and the bottom cover comes very close to the SSD, so if you install the “sandwich” of the adapter card and the NIC, the bottom cover may not be able to close. In other cases, if you were to use the m.2 slot for networking, you would need to use a SATA drive for storage, and the SATA drive caddy typically sits right above the m.2 slot. So the likelihood of collision between the SATA drive and the add-on NIC is pretty high… HP T630 would appear to be an exception; it has two m.2 slots next to each other. So, like I already said, risk and experimentation…