Separate connections over 1 network cable

Solution 1:

The issue with your proposed or current solution is that you lose a lot of bandwidth by splitting the cable, going from 1000 Mbps to 2 x 100 Mbps.

The obvious solution would be to work with VLANs. It would allow you to achieve most of your goals.

Note that I can, due to a lack of experience with PoE, not speak to the PoE part of your requirements, however you mentioned that PoE is not that important. I cannot say if my proposed solution would allow PoE or rule it out, however.

Working with VLANs will allow you to:

• Work with just one cable between roof and ground floor.
• Not lose any bandwidth
• Keep your LANs A and B completely separated.

What you need for that is a device that is capable of 802.1q based VLANs. Some examples of devices, that usually are VLAN capable, are:

• Managed switches
• 'Smart' switches
• Some WiFI Routers

You will need two of those devices. One will be on the roof and one in the ground floor. I will call them SwitchRoof and SwitchGroundFloor

This is what the configuration will look like:

SwitchRoof

• Port 1: connects to ISP modem
• Port 2: connects to roof AP
• Port 3: connects to ground floor (all pairs, 1000 Mbps)

SwitchGroundFLoor

• Port 1: connects to USG
• Port 2: connects to ground floor switch*
• Port 3: connects to roof (all pairs, 1000 Mbps)

• Note, depending of your physical layout and setup, this device (SwitchGroundFLoor) and the ground floor switch can be the same device. Likely, the Unifi switch in the ground floor is 802.1q VLAN capable and you would not need to get an additional device for the ground floor.

How to configure the switches (both on the ground floor and on the roof)

VLANs

• VLAN ID 1 will be your LAN (B)
• VLAN ID 2 will be your ISP/modem (A)

Port configuration

• Port 1 will be untagged in VLAN2
• Port 2 will be untagged in VLAN1
• Port 3 will be a trunk port with VLAN1 tagged and VLAN2 tagged

How does this work? The connection between roof and ground floor will be called a trunk. If data belongs to VLAN1 (B) it will be tagged as such and sent over the trunk and the receiving switch will remove the tag and send it out to port 1. Likewise, if data for VLAN2 (A) is sent over the trunk, it will be tagged as such and the receiving switch will forward it to port 3.