How to Discover Your Network Card Real Manufacturer
By Gabriel Torres e Cássio Lima on January 16, 2007

On-Board LAN

Sometimes you will need to know the real manufacturer of your network card, especially if your need some kind of support or its drivers. The problem is that the usually the manufacturer of the big chip found on your network card isn’t who manufactured the card. In this short tutorial we will teach you how to do that.

If your network card (also called LAN card, Ethernet card or NIC, Network Interface Card) is embedded on your motherboard – i.e., “on-board” – this procedure is quite easy and you have several options (if this is not your case, you can skip directly to the next page). Before talking about these options, there is something you need to know first. There are two options to create the on-board network card.

The first option is to use a separated network controller chip, like shown in Figure 1. In this case, you can use the drivers written for this chip, and get updated drivers on the chip manufacturer’s website.

Network Controller
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Figure 1: Network controller chip on a motherboard (in this example, a Realtek RTL8100C).

The second option is using a chipset that has already networking functions. In this case the chipset needs a small external chip to make the interface between the chipset and the network connectors (which includes coding data), also known as “physical layer”. This small chip is also known as “PHY” and it is usually smaller than a network controller chip (on Figure 2 you can see some unused solder markings around the PHY chip, where the manufacturer could use a full network controller instead of a PHY chip; compare the size of these markings to the actual chip used). Usually when your motherboard uses this approach, the drivers for the on-board network card are provided by the chipset manufacturer and not by the manufacturer of the PHY chip (there are some exceptions to this rule, though).

Network PHY Chip
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Figure 2: PHY chip on a motherboard (in this example, a Broadcom AC131 chip).

In summary, here is what you can do if your motherboard has on-board LAN:

On the next page we will explain what you can do if you have a “real” network card (i.e., an add-on card) and you need to find its manufacturer.

Real Network Cards

You have three options for getting drivers and support for real network cards:

On Ethernet networks (the kind of network most used) all network cards have a unique address called MAC (Media Access Control), which is stored inside the network card ROM memory. In theory there is no two network cards with the same MAC address (on some network cards you can change its MAC address, especially on on-board models; also some low-end motherboard manufacturers have the bad habit of shipping motherboards using the same MAC address on more than one board, which can cause trouble on your network).

When a machine needs to send data to another machine on the same network, it needs to know the MAC address of the target machine. When a data frame is sent over the network, only the target machine grabs it, as only it will have the target MAC address present on the “target MAC” field of the data frame.

The MAC address is a 48-bit (6-byte) address represented by a series of 12 hexadecimal digits. IEEE controls the attribution of MAC addresses and all manufacturers need an IEEE registration prior to start manufacturing network cards. This registration is called OUI (Organizationally Unique Identifier) and is a 24-bit (3 bytes) code. This OUI code is part of the MAC address. The rest of the MAC address is defined by the network card manufacturer, who should give a unique MAC address for each manufactured card, as already explained. For a better understanding, in Figure 3 you can see the structure of a MAC address.

MAC Address
Figure 3: MAC address structure.

A manufacturer can have more than one OUI code.

If you know the OUI code from the network card MAC address and are able to “decode” it – i.e., check on IEEE’s database what manufacturer has that code – you can easily find out who is the real manufacturer of your network card.

So the first step is to find out the MAC address of your network card. On Windows you can discover this very easily: click on Start, Control Panel and Network Connections. Double click your network connection (e.g., “Local Area Connection”). On the window that will pop up, click on Support tab and then on Details button. Your network card MAC address will be listed there as “Physical Address”, see Figure 4.

MAC Address
Figure 4: Finding out the MAC address of a network card.

As we mentioned before, the MAC address has 12 hexadecimal digits. You will only need to know the first six digits (first three bytes), which is the OUI code. In our example in Figure 4 they were 00-17-31.

The next step is going to IEEE’s website using the link below:

At this website, enter the three bytes under “Search the public OUI listing...” and hit Search! Then the IEEE search engine will tell you which company is proprietary of that OUI number – i.e., your network card manufacturer.

In our example, 00-17-31 belongs to ASUS, as we had an on-board network card on an ASUS motherboard.

Then it is just a matter of going to the manufacturer website to download drivers and/or get support. Click here to have a list of network card manufacturers and their websites.

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