STP Blocked Network Loop

B

bslow47

Young grasshopper
Jan 4, 2022
68
21
Texas
Good Morning all,
As always I appreciate all the help I receive from the board.
My UniFi USG router went out on me and find out they don't make them anymore as of 3 years ago and don't support them.
So I thought I would replace it for whatever took its place. The UniFi Cloud Gateway Ultra is what was recommended as a replacement.
After a little challenge, for me, I got the LAN back up but still have problems with the WAN. I connected everything the same way as I
had with the USG. Now it seams I have to log into the Gateway to see my topology and profiles rather than UniFi network application page.
Anyway, I now get a "STP Blocked Network Loop" error notification. I don't have a clue where to start with this. I am Gen X and I spoke floppy disc at one time.
A break down on my set up.
I have my new gateway connected to ISP. I have a switch connected to gateway. I have two desk tops connected to that switch (for ethernet) and another switch
that handles the security cameras and a LR access point.
On my topology page one of my desk tops has a pulsating circle around its icon that I don't know why. Maybe my STP problem but, I don't know.
I am also thinking that these problems are what is causing my WAN problems....
So, for starts, does anyone have a solution for my STP problem?

Thanks all
 
Update on the STP network loop. I discovered it is coming from one of my security camera ports (PoE). This particular camera is a different brand from the others but, it did not give me problems on the old USG router.
So does anyone know why one camera and/or port cause a network loop?
 
"STP Blocked Network Loop" means your Unifi gateway thinks there is a loop on your network. There's a small chance the STP (spanning tree protocol) notification is a false positive detection, but it is definitely worth investigating. A network loop causes serious performance issues, sometimes intermittently if something like STP is sometimes preventing the loop and sometimes not preventing it.

There are many ways a loop can be created, but the most common ways are:
  • If you connect two routers/gateways/switches together with two network cables, that creates a loop.
  • If you have 3 or more routers/gateways/switches, and you link them together in a literal loop as demonstrated in the picture below borrowed from this thread:

1755527605543.png

One of the links in a loop could even be wifi, for example if you have a wifi repeater that you connected to your network both wirelessly and wired, that could also cause a loop.

Generally it is safe to connect a PC to a network via multiple cables + wifi only because the PC does not bridge its network interfaces together the way a router/gateway/switch would.
 
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bslow47 said:
Update on the STP network loop. I discovered it is coming from one of my security camera ports (PoE). This particular camera is a different brand from the others but, it did not give me problems on the old USG router.
So does anyone know why one camera and/or port cause a network loop?
Click to expand...

Does that camera have wifi? How do you know that port is involved?
 
Insure that your wireless access point does not try to "mesh" with other mesh-capable wireless AP's on that same network segment.
 
bp2008 said:
Does that camera have wifi? How do you know that port is involved?
Click to expand...
Thanks for your reply,

The camera(s) is/are PoE and connected to a switch that is connected to another switch. They are not wifi. How I know the port is involved because on my topology that port was reded out with the same error message.
So I went back to look at it and it is no longer reded out but the error message is still present.
 
I did some googling, and it seems that ubiquiti hardware has issues where it sometimes has false-positive loop detections using STP (spanning tree protocol) and therefore it disables ports that are not part of an actual loop. Apparently you can turn off STP in the global settings to work around this issue. The switch would no longer detect and disconnect a real network loop of course, but that is better than constantly detecting loops that don't exist and shutting off ports for no reason.
 
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