networking - Ethernet port re-transmission frequently
2014-07
Earth Engine
We have a laptop that uses its Ethernet port to connect to a device-local network, and wireless for Internet.
Recently we installed Wireshark to diagnose some network problem. We found a lot of TCP re-transmission packets (which indicated as dark or red or other unconformable colors).
Our observation is that this only happened in the Ethernet port. Even it is connected to the Internet it is still the same situation. However the same thing does not happen in the wireless link.
Also, the re-transmission happened very frequently and usually repeated 4 times. For example, we observed 4 continuously duplicated SYN before any other packets (interval less than 200ms). This is unusual, since I think TCP re-transmission shall only happen when time-out occurs.
It looks like the source is in the laptop end, because 1) the above SYN packets were sent from the laptop; 2) when connecting to Internet, connections to all over the world have the same problem.
There is no noticeable effects in the application level. But I wonder what is wrong with this Ether port? What shall we do to fix this?
Azz
I have had a similar issue before, where I would see duplicate TCP packets being sent, about 3 per packet if I recall.
The issue I had was with drivers/software installed in Windows.
To rule out the possibility of it being a hardware issue, boot up in a linux LiveCD and verify whether the issue occurs then. If not, it's likely a driver/application issue in Windows (I'm assuming Windows here, correct me if I'm wrong).
How I found mine, was by going to Control Panel -> Network and Sharing Center -> Change Adapter Settings.
From there, right click on the adapter and click Properties.
You should see a window like this:
The problem I had, was that there was a piece of software installed (particularly, a wireless hotspot application) that was causing the repeated TCP packets.
My recommendation is to look under your network adapter, and try to find items that do not look like they came with Windows, temporarily disable them (one at a time), and perform the tests with Wireshark again to see if the problem has gone away.
Ian
I've got a XFX 680i motherboard that is about 2 years old now. You'll see it has 2 on-board gigabit ethernet ports.
Starting maybe a week or so ago, my internet connection would go down, and I'd have to Disable and Enable the network connection in the Network Properties page of Windows 7 to get it to come back up again. Then some random time span would pass, and I'd have to do it again. Could be minutes, could be hours or days.
This section of the story is probably unrelated, but, yesterday my hard drive crashed. Eh, hard drive was a couple years old, fine. That's life. So I get a new drive, pop it in, reinstall, yada yada.
Now the network is going down every few minutes, on both ports. My laptop, when plugged into the same router ports with the same ethernet cables, is rock solid.
OK, must be the ports, I reason to myself....
So I go out, buy a new Gbit ethernet PCI card and install it.... (don't even get me started on Linksys not putting out Vista / Win 7 drivers for the EG1032... bastids). So yeah, no drivers for Windows 7. Luckily the Windows 7 Realtek drivers work for it. So I get those installed and get the network up.
Rock solid network, no more issues.
So, it's pretty clearly narrowed down to the ethernet ports themselves on the motherboard have gone bad. Well, to be more precise, whatever it is that's controlling both ports has gone bad.
I've tried installing and uninstalling the nForce ethernet drivers. No change. Nvidia's Network Access Manager was causing problems with certain application's ability to connect to the internet, however.
Anyway, what exactly is my question...
What is it on the motherboard that controls the ethernet ports, and why might it start failing in this way (works for a little bit, then requires a Disable / Enable cycle to reconnect)?
edit - oh, and my mouse scroll wheel went out too! ... what a monday...
David Spillett
Both network ports on the same board going odd at the same time is not unexpected - they will both be running from the same controller chip.
It could be that the controller chip on the motherboard is on the way out, but I doubt it as that chip will be controlling much else at the same time and you are not seeing problems with other devices. I could be wrong there, of course. My suspect would be a driver issue rather than a hardware one, especially since resetting the network devices without a power cycle does the trick (at least temporarily).
Mun
It might be unrelated, but I had a similar type of problem when using the Windows 7 Beta on my laptop, where both my wireless and ethernet connections would stop working. The only way to get it working again was to reboot - even disabling and re-enabling didn't solve the problem. Eventually I gave up with the beta because of it, but I've been using the RC for a while now and that's been fine.