Using WiFi bridge to locate servers in another room

With three rack servers (although only two are running), it is not really sane to keep them running in the same room as where I usually do my work. Yes, the R720 is actually quite silent because it is a 2U server, and the R430 is usually silent since it is not under load. But trying to run all of them in a single room can overload and trip the electricity breaker... so I thought about how to distribute them. The challenge is to run LAN cables all over the place, which is difficult since I don't want to drill any holes.

In the end, I settled on the "Media Bridge" operation mode found in Asus WiFi routers. What it does is basically allow you to connect devices via Ethernet to the router, and use that router to connect to another router via WiFi.

So I got myself a pair of Asus WiFi 5 routers. Yes, WiFi 5, not WiFi 6... because Asus only has ONE WiFi 6 router with 8 Ethernet ports, and it costs an arm and a leg. Why 8 ports? Because 8 ports allow me to connect two rack servers (each of them has 4 Ethernet ports plus an iDRAC port). Meanwhile, the RT-AC88U can be found at a much lower price on Yahoo! Auction, and it has 8 Ethernet ports. (The Asus GT-AC5300 also has 8 Ethernet ports, but as a "gaming" router, it gathers a lot more attention on the used/secondhand market and commands a correspondingly higher price. The higher speed on the 5 GHz band is also split between two SSIDs, so it will not be manifested when operating in "Media Bridge" mode since that mode allows only the use of a single SSID.)

The RT-AC88U will be the main router connected to the Internet. It operates in the router mode and is located in my work area, and connects to the R720, my desktop, and laptop via Ethernet. My original extension also connects to this router.

The other router is also a RT-AC88U router operating in the "Media Bridge" mode in another room and connects to the main router via WiFi. The R430 is connected to it via Ethernet, and in the future, I should be hooking up the R320 to it too (once I have determined a proper use case for it and gotten the required hardware).

 

My old RT-AC59U router is also operating in "Media Bridge" mode and it serves to connect the iDRAC of the R430 (and R320 eventually) to the home network at a theoretical speed of 867 Mbps.

 

Since the RT-AC88U has a max speed of 2167 Mbps over 5 GHz, this means I should be able to get at least 1 Gbps connection between all my devices. As the 4 Ethernet ports (1 Gbps each) on the R720 and R430 are in their own respective network bonds, this also means that the two servers can theoretically communicate with each other at up to 2167 Mbps (although I would be happy as long as they can achieve anything above 1 Gbps). The 4-port network bond for each server also means that, if I eventually get a pair of high-speed WiFi 6 routers (with 4804 Mbps at 5 GHz), I may even be able to push the theoretical limit to 4 Gbps. Anyway, these are theoretical speeds. I am getting an average connection speed of 1000 Mbps between the two RT-AC88U routers. (Update: iperf shows that the actual speed between the two servers is around 600 Mbps.)

Now to think of a use for the R320... 😅

Note: I know some Asus routers like the RT-AC88U have AiMesh support, which allows them to operate as a mesh to extend WiFi coverage in the house without having to set up "Media Bridge" mode. However, AiMesh nodes will then have to split their bandwidth between backhaul and WiFi extension, which effectively halves the wireless speed connection of wired devices connected to the node. In "Media Bridge" mode, the entire bandwidth is used for backhaul, which better serves my need to extend my network to a couple of wired devices in another room without having to run LAN cables.

A note about "Media Bridge" mode: I think this is what people usually call "repeater bridge" or "client bridge".

Note: I actually got a defective RT-AC88U when I was sourcing for the second router. Somehow, the MAC addresses on the 2.4 GHz radio shows that for the 5 GHz radio, and I get a weird case in which the router thinks it is transmitting at 2.4 GHz when it is actually transmitting at 5 GHz. And because it does not see a MAC address for its 5 GHz radio, it thinks it cannot transmit at 5 GHz. So I managed to get a third one (router only, without antennas and power supply) and reused the antennas and power supply from the defective second router. The RT-AC88U with a defective WiFi radio is likely to end up being a 9-port router if I need to connect more devices in the other room. This can be done by configuring the router to operate in AP mode, then turning off its radios (since they don't work anyway).

 

Note about link aggregation:

I have the NICs in my R720, R430, and R320 in a network bond. The four Ethernet ports of my R720 are connected to the main RT-AC88U. However, I had connected two of the ports on the R430 to the RT-AC88U media bridge and another two ports to the RT-AC59U media bridge. It gave me very intermittent connection with the R430, which I thought was due to poor WiFi signal. But when I connected all four Ethernet ports on the R430 to the RT-AC88U media bridge instead, I got a good and consistent connection. Lesson? For a network bond, connect the ports to the same router.