MBP - Second WiFi Adapter possible?

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Level 1

8 points

MBP - Second WiFi Adapter possible?

I need to connect to two networks simultaneously for a project I'm working on, and therefore I need two WiFi adapters on my Macbook Pro. I will use the built-in adapter to connect to our 10.x.x.x network, and then I need a second WiFi adapter to connect to our 192.168.2.x network. The project I'm working on transforms packets from one network into messages on the other network, and therefore must connect to both networks simultaneously. Can a Macbook Pro support two WiFi adapters? My plan is to purchase an MacOS compatible USB WiFi dongle (assuming they exist) and use that. This was easy not impossible to do on a Windows box, but obviously I don't want to go backwards if I don't have to. The Windows compatible dongle does not appear to work on the Mac.

MacBook Pro

Posted on Apr 5, 2017 2:04 PM

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Answer 1

Apr 5, 2017 3:06 PM in response to DThompson551

must connect to both networks simultaneously.

The Mac sends packets bound for the Internet to the Topmost, Working Interface showing in:

system preferences > Network

There is no ability to do load-sharing or any other division of packets bound for the Internet. Only if the Topmost Interface stops working will the list be re-ordered to use a different Interface.

If you have a device on your local network that has a local Address (not a Router) such as a network Storage device, that can successfully be placed on you local network with a manual IP address and you can talk to it directly through a second Network Interface.

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Answer 2

Apr 5, 2017 2:54 PM in response to DThompson551

You can't connect to two networks at the same time. Your computer will not know when and how to connect to which. A router can bridge two networks but you have to define the route in the router. I'm not sure if consumer level routers can do this or if it requires an enterprise level router.

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Answer 3

DThompson551 Author

Level 1

8 points

Apr 5, 2017 4:23 PM in response to DThompson551

Brillant ! It turns out that I am able to use the old WiFi USB Dongle that I had on the Windows box. It required some new drivers for Sierra that were well hidden. But now it appears to work. The drivers were located here:

http://static.tp-link.com/TL-WN725N(US)_V2.2_160822_Mac_1475910227538e.zip

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Answer 4

tjk

Level 9

51,192 points

Apr 5, 2017 2:14 PM in response to DThompson551

Hi,

They certainly exist: https://eshop.macsales.com/item/Edimax/EW7822ULC

The problem to overcome is how to get the Mac to "see" two different networks at the same time; I believe that would need to be software and I don't know if it exists.

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Answer 5

DThompson551 Author

Level 1

8 points

Apr 5, 2017 2:40 PM in response to tjk

I agree tjk. That is exactly the problem to overcome. Maybe I just need to purchase that dongle and see if it works. That seems like a potential waste of time an money though. I'd like to hear from someone who has either done it, or knows it will or will not work.

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Answer 6

DThompson551 Author

Level 1

8 points

Apr 5, 2017 3:24 PM in response to BobTheFisherman

I hear you Bob. But I can do it on a Windows laptop. It seems like I should be able to do it on a Mac.

As for knowing how and when to connect to which network, that's really easy. Each adapter is on a separate network with separate addressing. The 10.x.x.x network is on adapter A. The 192.168.x.x network, that's on adapter B. There's no confusion on this aspect of the project. The 192.168.x.x network is not connected to the internet and there are no 192.168.x.x machines on the internet.

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Answer 7

DThompson551 Author

Level 1

8 points

Apr 5, 2017 3:36 PM in response to Grant Bennet-Alder

Thanks Grant - We're in agreement on the topmost working interface being the one that connects to the Internet, in my case through the 10.x.x.x network. I am not doing load-sharing or division of packets bound for the Internet.

And you're saying is that I should be able to connect to a second, private local network, in my case the 192.168.x.x network if I get a second network interface. Where you threw me is when you said 'not a router', because clearly I need to connect to that router in order to get to things on that network, right?

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Answer 8

Apr 5, 2017 3:59 PM in response to DThompson551

It seems like it should be true that you need a Router. But it is not. (Please forgive me if this seems like splitting hairs.)

For example, when you have devices on the same subnet (think file sharing or Printing to a local Network printer) those packets go DIRECTLY to the other device, because they do not need Address translation to be sent to the right station.

What you need is a Switch -- the part of a Router that stores and forwards packets to other devices. Although there is a Switch built into every Router, you do not need or want it to Route anything -- just send it along to the stated destination, WITHOUT changing its address.

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Answer 9

Apr 5, 2017 4:06 PM in response to DThompson551

Wait, I just re-read my other answer. You may not need another Interface if you set your network up correctly.

Packets bound for the Internet are sent to the Address of the Router, so that it can perform Network Address Translation and act as your agent on the Internet. (e.g., 10.10.0.1)

Packets sent to any other address on your local network do not get Routed, but merely stored and forwarded locally, using only the Switch function of your Routers and Switches, not Routing.

I have a Network Printer on my Network at xxx.yyy.zzz.17 I can send stuff to it anytime, and its traffic does not go on the Internet.

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Answer 10

DThompson551 Author

Level 1

8 points

Apr 5, 2017 4:33 PM in response to Grant Bennet-Alder

Of course, for the setup I'm talking about, it needs two interfaces. These are two separate, unconnected networks. It is impossible to get from one to the other. That's by design. Nothing on the second network can get to the internet without passing through the app I'm writing on the Mac.

Your network printer, on the other hand, can, and probably does talk to the internet. The stuff you send to it for printing doesn't, but if it's a wireless printer then at a minimum it likely sends stats to its hive.

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