I have a thinkpad, and for some reason my wifi firmware crashes at random times, I can't fix it.
Other annoying problem: if I start my computer with the jack plugged in, unplugging it doesn't switch to speakers.
After five years I discovered why my network goes down (2020)
11–20 of 38 posts
Re: After five years I discovered why my network goes down (2020)
#12I recently solved a 5-10 year bug in a similar vein. My local network DHCP shared an IP space with the VPN to which I have been connecting. This was causing intermittent and "unexplainable" connection issues that were ultimately due to plain old IP-address collisions.
Sadly, the immense joy that I felt upon resolution is mysteriously lacking from this person's post.
Edit: DHCP not DNS
Re: After five years I discovered why my network goes down (2020)
#13We had Dell laptops with the dock. If you undocked the laptop under the right circumstances, which we could never determine, the dock would go into a mode where it would start spamming IEEE 802.3x PAUSE frames into the network as fast as it possibly could.
Our switches didn't handle this correctly and would forward the PAUSE frame as it if it were a broadcast. When this happened, the entire network would cease to function until the offending dock was found and disconnected.
Re: After five years I discovered why my network goes down (2020)
#14Why would a MAC address duplication "lock up" your whole network? I would guess that at worst that particular laptop would either intermittently get packets or not get packets at all. Which is bad, but not a "lock up". Other stuff should still work.
Ethernet switches keep track of which ports have which MAC addresses behind them. This is stored in the CAM table of a layer 2 switch. When duplicate entries occur, this result in MAC address flapping and switches have different ways of handling this, which may result in network instability.
Re: After five years I discovered why my network goes down (2020)
#15I've drop down two networks in my life,
First time I run a dhcp server by accident and suddenly went sideways but the blast radius was small,
Second time and more interesting one, My campus had a mac address allow list; when I got a new computer and didn't want to handle the process of updating my access access permission, I just run a script to change my mac to the old known address.
Later, I also sold the old computer to another colleague which didn't bother to register as well since everything was working. Long story short, we keep disconnecting each other.
One day I was, "c'mon, I'll fix this". Opened wireshark and started to capture network traffic. I've got a list of mac addresses from the pcap dump and every time I got disconnected, I ran the script spoofing my address to the next one in my list.
That worked fine until the day I spoofed the mac address of a central managed switch that shit itself out of the network.
:)
Re: After five years I discovered why my network goes down (2020)
#16I don't understand networking enough or maybe what docks actually do. What was the OOP's solution?
Re: After five years I discovered why my network goes down (2020)
#17I used to have a dell vostro notebook that every time I logged into the network with windows, it would drop every other device on the wifi. Funny thing, is that if I used linux, the router would be alright and not collapse. Never found out the reason. In the end I divorced the wife and she got that notebook. Wifi is weird.
nice ! not only did you get rid of both issues, you made sure they interact with each other for maximum chaos
Re: After five years I discovered why my network goes down (2020)
#18I have a dumb 1gb switch that hangs semi randomly but very seldom. Not all devices go throuh it,so the first time it happend was crazy to debug. Because I didn't keep track of which devices go throuh the switch and which ones go direct to one of the 4 ports of the router.
And when I found out: "Mother f
Re: After five years I discovered why my network goes down (2020)
#19I find it curious that the wifi interface and the USB/ethernet interface are using the same MAC address. Nothing keeps a computer from being attached with both at the same time, in which case this would definitely break things.
Also, doesn't Apple do MAC randomization on WiFi by default? So, it should be using the same MAC that already exists on the machine already.
Re: After five years I discovered why my network goes down (2020)
#20I find it curious that the wifi interface and the USB/ethernet interface are using the same MAC address. Nothing keeps a computer from being attached with both at the same time, in which case this would definitely break things.
Probably DHCP lease cache problem.