Spanning Tree Protocol (STP) interrupting network traffic (streaming)

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Kanji-San

Regular Contributor
I have been hunting down a sporadic issue where (audio) streaming activity has been interrupted on my network. I think I finally tracked it down to my Samsung Smart TV which generates this in the syslog every time it's turned on or off:

Code:
Sep 11 12:37:44 kernel: eth1 (Ext switch port: 0) (Logical Port: 8) (phyId: 8) Link UP at 100 mbps full duplex
Sep 11 12:37:44 kernel: br0: port 1(eth1) entered listening state
Sep 11 12:37:44 kernel: br0: port 1(eth1) entered listening state
Sep 11 12:37:46 kernel: br0: port 1(eth1) entered learning state
Sep 11 12:37:48 kernel: br0: topology change detected, propagating
Sep 11 12:37:48 kernel: br0: port 1(eth1) entered forwarding state
Sep 11 12:37:51 kernel: eth1 (Ext switch port: 0) (Logical Port: 8) (phyId: 8) Link DOWN.
Sep 11 12:37:51 kernel: br0: port 1(eth1) entered disabled state
My understanding is this is due to the spanning tree protocol (STP) which is enabled in my router (RT-AX88U). I have two unmanaged switches and an AiMesh node in my network.

My Samsung TV is the only device triggering this. I am not quite sure what happens but it seems like this is the reason my streaming is interrupted for several seconds since this is at the exact same time the TV is switched off or on. Does this make sense?
 

coxhaus

Part of the Furniture
STP will stop network storms in your network. I am not sure why a TV device could cause a loop? Usually it is a couple of cables plugged into a switch that causes a loop.
 

Kanji-San

Regular Contributor
STP will stop network storms in your network. I am not sure why a TV device could cause a loop? Usually it is a couple of cables plugged into a switch that causes a loop.
I don't think the TV causes a network storm. As a matter of fact, I don't think there are any network loops or problems except the TV triggers something STP-related which disturbs the network.
 

ColinTaylor

Part of the Furniture
I don't believe this is anything to do with STP. You can try turning off STP on the router but my guess is that you will still see the same messages.
 

coxhaus

Part of the Furniture
Maybe you have some bad STP code.

I have seen networks run with storms in them. They tend to be slow to respond.
 

Kanji-San

Regular Contributor
I don't believe this is anything to do with STP. You can try turning off STP on the router but my guess is that you will still see the same messages.
You are right. I disabled STP in the router and these messages still show up. Why does no other devices connected to the router generate these messages?
 

Kanji-San

Regular Contributor
What other Ethernet devices do you have directly connected to the router's LAN ports?
An A/V receiver, Apple TV, PS3, and an unmanaged switch.
 

ColinTaylor

Part of the Furniture
An A/V receiver, Apple TV, PS3, and an unmanaged switch.
I would have expected the same sorts of messages if you physically unplugged any of those devices. Can you try unplugging the Apple TV?
 

Kanji-San

Regular Contributor
I would have expected the same sorts of messages if you physically unplugged any of those devices. Can you try unplugging the Apple TV?
I agree, I would expect the same messages for other devices.
I unplugged the Apple TV box and these are the only messages that I get:

Code:
Sep 12 10:03:19 WLCEVENTD: Disassoc B8:53:AC:44:31:DE
Sep 12 10:03:19 WLCEVENTD: Disassoc B8:53:AC:44:31:DE
Sep 12 10:03:19 hostapd: eth7: STA b8:53:ac:44:31:de IEEE 802.11: disassociated
Sep 12 10:03:19 hostapd: eth7: STA b8:53:ac:44:31:de IEEE 802.11: disassociated
 

ColinTaylor

Part of the Furniture
I agree, I would expect the same messages for other devices.
I unplugged the Apple TV box and these are the only messages that I get:

Code:
Sep 12 10:03:19 WLCEVENTD: Disassoc B8:53:AC:44:31:DE
Sep 12 10:03:19 WLCEVENTD: Disassoc B8:53:AC:44:31:DE
Sep 12 10:03:19 hostapd: eth7: STA b8:53:ac:44:31:de IEEE 802.11: disassociated
Sep 12 10:03:19 hostapd: eth7: STA b8:53:ac:44:31:de IEEE 802.11: disassociated
Is that the MAC address of your Apple TV? It shows it being disconnected from WiFi not Ethernet. Or maybe it failed over to WiFi when you unplugged the Ethernet (you would have an association message in the log) and then failed back when you reconnected it?
 

Kanji-San

Regular Contributor
Is that the MAC address of your Apple TV? It shows it being disconnected from WiFi not Ethernet. Or maybe it failed over to WiFi when you unplugged the Ethernet (you would have an association message in the log) and then failed back when you reconnected it?
Sorry, this is not the MAC address of my Apple TV. This is an iPhone and unrelated to this.

However, I solved the mystery why only my Samsung TV showed these Link UP and DOWN message in the syslog. The RT-AX88U has 8 Ethernet ports and they are grouped like this:

InterfacePhysical Port
eth0WAN
eth1LAN 4
eth2LAN 3
eth3LAN 2
eth4LAN 1
eth5Bridge of LAN 5 - 8
eth62.4 GHz Radio
eth75 GHz Radio
source: https://wu.renjie.im/blog/network/ax88u-vlan/

My Samsung TV was plugged into LAN 4 which is eth1. Only eth1-4 show these Link UP and DOWN messages because LAN 5-8 seem to be a hardware bridge and don't show these messages. All my other devices were plugged into LAN 5-8.

It seems like my streaming interruptions might be unrelated to STP and rather caused outside my network.
Thanks everyone for the help :)
 

thecheapseats

Regular Contributor
generally, STP is there to mitigate nonsense/mis-configuration oversights - and is your friend... others may disagree... whatever...
 

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