Re: Ethernet switch disconnects devices directly connected to G1100
gs0b
Community Leader
Community Leader

In the diagrams you posted, you show the cable between the router and the switch as "outdoor cat6."  How long is this cable?  Is it running between buildings or outside somewhere?

Can you try putting a switch right next to the router, then plug the run to the other switch into it?

Re: Ethernet switch disconnects devices directly connected to G1100
Cang_Household
Community Leader
Community Leader

I want the original poster to make two observations.

Are the LED lights still lit when the disconnection happens? 

Are the LED lights on both switches flashing crazily when you know there is no significant amount of traffic on the line? If they do, this is a sign of layer 2 or 3 looping. I wish you have my Cisco switch, it detects loops by itself and displays on the port. A flashing yellow calling for attention.image

Reposting image: deliberately created a loop for demonstrating FiOS Network Extenders cannot be uplinked by both MoCA and Ethernet.

Are your dual interfaced-Macbook's connections bridged? If they are, this is essentially having a layer 2 loop between the WiFi and the ethernet switch. Since you said the WiFi still works, this possibility can be ruled out.

Re: Ethernet switch disconnects devices directly connected to G1100
mcar91
Newbie

After a few days of things working well, the issue cropped up again. I noticed the lights on the switch and the G1100 are flashing like crazy. On the Netgear switch, it’s the port my PC is using and the one running to the G1100. The port connected to my MacBook is not flashing (cuz it’s disconnected currently). 

any ideas on how to eliminate a loop on Windows? It’s only connected via Ethernet. WiFi on the machine is disabled. 

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Re: Ethernet switch disconnects devices directly connected to G1100
mcar91
Newbie

I also ran the Windows network troubleshooter and it says the Ethernet network doesn’t have a valid IP and the default gateway is not available. 

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Re: Ethernet switch disconnects devices directly connected to G1100
Cang_Household
Community Leader
Community Leader

@mcar91 wrote:

I noticed the lights on the switch and the G1100 are flashing like crazy. On the Netgear switch, it’s the port my PC is using and the one running to the G1100. 

any ideas on how to eliminate a loop on Windows? It’s only connected via Ethernet. WiFi on the machine is disabled. 


You definitely have a loop somewhere, otherwise the LEDs won't "flashing like crazy" when you know there isn't a significant amount of traffic.

For Windows bridging, go to Control Panel > Network and Sharing Center > Change Adapter Settings, see if there is a router icon as an adapter.

Re: Ethernet switch disconnects devices directly connected to G1100
mcar91
Newbie

@Cang_Household wrote:


You definitely have a loop somewhere, otherwise the LEDs won't "flashing like crazy" when you know there isn't a significant amount of traffic.

For Windows bridging, go to Control Panel > Network and Sharing Center > Change Adapter Settings, see if there is a router icon as an adapter.


I'm brand new to Wireshark so I just fired it up with all the default settings. I ran two captures and the results are on this link.

https://we.tl/t-l6bMRZrfbF

"wireshark_switch_no_router" is the PC connected to the switch and the switch is not connected to the router. In this state, the light on on the port connecting to the PC was flashing rapidly. Seemingly to nowhere. 

"wireshark_switch_connected_to_router" is the PC connected to the switch and the switch connected to the G1100. When I captured this, the problem was happening. The G1100's ethernet devices were down and the PC's internet connectivity was also down. 

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Re: Ethernet switch disconnects devices directly connected to G1100
Cang_Household
Community Leader
Community Leader

First of all, sharing device configuration on third-party platforms is very insecure.

For WireShark, you are capturing the loopback traffic. You should select the Ethernet adapter. Or, you have selected Ethernet adapter and we are seeing bunch of loopback traffic? If the latter is the case, that is a sign of layer 3 looping.

Your Adapter property shows the device does not have an IP address. Did you release the IP address? None of your adapter is bridged, which is good.

Re: Ethernet switch disconnects devices directly connected to G1100
mcar91
Newbie

Well things have gotten even stranger. Since the last time I posted, I replaced the G1100 with an Airport Extreme I had laying around. I also set the PC with a static IP address which I confirmed was working correctly. The network ran nicely for a few hours and then the same issue popped up. The lights on the switch were blinking like crazy and all the ethernet devices went down. The new behavior this time, though, is that all wifi devices ALSO went down.

So it's not the G1100's fault.

It's not the switch's fault because I've tried 2 TP-Link devices and a Netgear and they've all had the same behavior.

I feel like it MUST be the PC or the cable running between the router and the switch upstairs. The cable works... is it really possible the cable could just sometimes mess up the entire network?? 

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Re: Ethernet switch disconnects devices directly connected to G1100
Cang_Household
Community Leader
Community Leader

That's a broadcast/multicast storm. G3100/G1100's APs are smarter than Airport Extreme to block broadcast storms, probably.

Have you tried what I said in the previous post. I am not trying to be didactic here, I just want to be helpful.

Re: Ethernet switch disconnects devices directly connected to G1100
mcar91
Newbie

Yes, I also ran Wireshark on the ethernet adapter. I'm really not sure what I'm supposed to do with that captured data. I also posted on reddit and someone there mentioned it just looks like the PC is unable to get an IP address. Nothing about what may be causing the storm. 

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