The is going to be rather direct and blunt. Here on this forum they take a very dim view of spam or any other attempt to promote a product by using this form.
If I am mistaken, I apologize. I believe I know the product you are fishing for, is made here in the United States, and is called a mechanical Ethernet switch.
Frankly, I think it's a bad idea. Allow me to explain.
The KVM switch is often a mechanical device that is used by an administrator has to reduce the number of keyboards and monitors and mice on his desk at one time. This is not sort of thing that a user would normally use in day-to-day activities. Those kind of switches control either low speed devices, or devices that do not require synchronization for the kind of work the administrator does. When he throws the switch is monitor will momentarily lose sync, but he doesn't really care.
No then, If a user had to switch back and forth constantly between two computers than one monitor using a mechanical switch it would be very irritating. If for some reason a user needs to quickly switch between video sources, they ought to be synchronized.
Now here is why I am very critical of a mechanical Ethernet switch. There is no easy way for the user to know when the network is or is not active or when it might send another packet . Any chemical switch would certainly disturb the connection.
In the event that you and quickly need to go from one network to another, you can't. You could set up a patch panel and simply unplug the cord from one connection and plug it into another. That would be no better or worse than using a mechanical switch. Actually, it's probably a little better. When you switch to another network it's going to take a while for the connection to repair itself, unless you just happen to have a fixed IP address for your workstation. Even so, physically disconnecting your workstation from one network and plug it into another is very annoying to the network. It is much more elegant for the workstation to log off of one network and log on to another. That sort of thing can be done in software.
Now if you're testing security software, and the network you are working with are very important, you should rethink your entire project. If your network is serious you will not use it as a test ground for anything. You only test security issues with a special setup that keeps you absolutely off of your commercial network.
If this sounds very, very opinionated, it is. But I do believe my opinion is shared by others who currently are working in the IT industry. Administrators and technicians who need to do occasional testing on an active network will use patch cords and hit the network during that time when the disturbances are least likely to interfere with the work of others.
Anyway, if you wish to use mechanical switches to do what you're wanted to, they have been around for a long time. These types of switches are sometimes called
leaf switches. They are very reliable, have very low crosstalk, and can be configured or purchased either as make before break or break before make operation. They were/are commonly used both in the telecommunication industry and the broadcast industry are many years.
Yes, I am often very, very wrong. If so, somebody else will correct me.