How do I know if I got a STP / Broadcast Storm problem with Sonos?

  • 8 October 2017
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I saw this video that explained to me the Spanning Tree Protocol and Broadcast Storms:

https://www.youtube.com/watch?v=IAIsFX1XPHo

Since I have multiple Sonos speakers connected with wire and some are wireless, and by connecting at least one speaker with wire will make that speaker the hub of the SonosNet, as I understand it.

So my setup might be applicable to the "Broadcast Storm" problem.

From what I understand, this can be prevented by two ways:
- Sonos has their own STP solution, so even if you mix wired and wireless speakers, "it should work", correct?
- You start using switches that supports STP (or one of the other variants RSTP/MSTP), which will notice duplicated packets and remove them, correct?

I have a router and from that I branch out to Netgear GS105 switches (which then might connect to other GS105 switches - I have know idea if they have STP support or not).

But my question is...
- How would I even know if I got "Broadcast Storm" problem in my home network?
- Everything seems to be working fine here, but maybe that's a false insurance.
- Is there a way to know if my current network setup mitigates "Broadcast Storms" created by Sonos speakers?

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4 replies

If your network isn't totally crippled, stop worrying
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Like John said, a broadcast storm will usually cause switches and/or routers to stop responding to anything else, making your network more or less stop working entirely. So if things are working, then you aren't having any problems with a broadcast storm.

Using switches that support STP can cause issues if some of the STP settings aren't set correctly. It could cause your Sonos devices to use wireless connections instead of wired ones, or block the STP packets that the Sonos devices send, leading to the broadcast storm issue.

The Netgear GS105 switches that you have are "dumb" unmanaged switches, so they don't have STP settings to worry about. STP settings can be found in many (but not all) "smart" switches (the "smart" designation indicates that most configuration is done through a web-based interface), and nearly all switches that are managed with some sort of command-line interface.
If you want to see what happens during a broadcast storm then take one cable and plug both ends into the same switch. This will loop the switch up. Give it some time and everything will slow to a crawl.

I just had to deal with this issue at one of our sites recently. One of our junior guys decided to disable spanning tree because it makes the ports come up faster. Well someone decided to clean up the loose cables and plugged both ends into the data jacks under their desk.
Userlevel 7
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One of our junior guys decided to disable spanning tree because it makes the ports come up faster. Well someone decided to clean up the loose cables and plugged both ends into the data jacks under their desk.
Not related to Sonos, but just wanted to offer some help :)

If it's possible with your switches (I know it's possible with Cisco, not sure about others)... Set BPDU Guard so that it is enabled by default when Portfast is on, then enable Portfast on the ports that your users connect to. Portfast will bring the port up faster, even with Spanning Tree enabled, and BPDU Guard will disable the port if it sees BPDUs (a looped port will cause BPDU's from one port to be seen on another, causing one of the ports to become disabled and stopping the loop). If you have devices that NEED to send BPDUs (like Sonos, or a downstream managed switch), then you disable Portfast, which in turn will disable BPDU Guard.