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[SOLVED] Unstable LAN wired connection

Linux Kernel, Network, and Services configuration.
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andoru
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[SOLVED] Unstable LAN wired connection

#1 Post by andoru »

I previously asked for assistance here:
https://reddit.com/r/linuxquestions/com ... onnection/

I seem to have some problems getting a second-hand machine (HP Elite 8200) to properly connect. The connection is very unstable, many times not being able to load any pages in the browser, getting pings over 200ms, and getting many 408 HTTP errors.

I've checked Debian and Linux Mint so far, and both have this issue. I also wanted to try booting into a live session of both System Rescue CD and Gentoo as per the suggestions of the commenters in that reddit post, but I was unable to make the PC boot into those two either from grml-rescue nor from a pendrive.

I've checked the ethernet port in the back of the machine, and it is intact, the cable isn't damaged as I've tried it with another machine, and it works as expected.
Also there are no signs that the motherboard and it's components are damaged (bloated capacitors, stains, blown chips, corroded traces, etc)

What I currently assume to be the culprit: the network interface on the machine is broken/dead in a way that's not obvious. Or there's something misconfigured somewhere (either router, BIOS or in the OS), or the driver for the network interface (which is an Intel 82579LM) is buggy.

Now I know that the former cannot be fixed without replacing the whole machine or getting a network card, but could someone suggest what I could try to diagnose software-wise, in case it's the latter case?

Thank you in advance!

EDIT: tl;dr - The culprit was the cable. It's not damaged, and I can connect other devices to it and it works, but this particular NIC doesn't really like it. I'll be changing the cable with a CAT6 one and hopefully I won't have this issue.

EDIT2: Changed the old cable with a Cat 6a S/FTP one, and now the NIC works properly.
Last edited by andoru on 2018-04-21 15:34, edited 4 times in total.

Dai_trying
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Re: Unstable LAN wired connection

#2 Post by Dai_trying »

If you could install inxi and post the output of inxi -n it might help diagnose your problem.

Also I noticed you mentioned something about gigabit connection in the reddit post which makes me think you might need the tg3 firmware which I believe is in the package firmware-misc-nonfree

andoru
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Re: Unstable LAN wired connection

#3 Post by andoru »

Alright, will install inxi and post the output.

The network interface is gigabit capable, but the connection itself is only 100mbps.
I'm a bit queasy about installing nonfree stuff, but I'll try it and see if it improves anything. Thank you!

EDIT: Love your username!

Segfault
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Re: Unstable LAN wired connection

#4 Post by Segfault »

In cases like this I usually reach for my trusty 2 GB USB stick with latest SystemRescueCD on it. Just to test if issue is with installed Linux or hardware.

andoru
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Re: Unstable LAN wired connection

#5 Post by andoru »

As I previously mentioned, I tried booting System Rescue CD from within gldr-rescue, and since that didn't work, I then wrote it to a USB pendrive, but the machine just won't boot it...
I was lucky enough that both the Debian netinstall iso, and Linux Mint's iso work with this machine. I have no idea why the others don't budge...

EDIT: I cannot grammar.

Dai_trying
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Re: Unstable LAN wired connection

#6 Post by Dai_trying »

andoru wrote:I'm a bit queasy about installing nonfree stuff, but I'll try it and see if it improves anything. Thank you!
It's one of those things with firmware, you sometimes need the non-free firmware to be able to use some hardware properly, but you can always disable the non-free repository once you have the required firmware (if it is actually needed which hopefully we will find out), and you're welcome.
andoru wrote:EDIT: Love your username!
Thanks, Me too :D


andoru
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Re: Unstable LAN wired connection

#8 Post by andoru »

Dai_trying wrote:If you could install inxi and post the output of inxi -n it might help diagnose your problem.

Also I noticed you mentioned something about gigabit connection in the reddit post which makes me think you might need the tg3 firmware which I believe is in the package firmware-misc-nonfree
Haven't got the chance to try installing the firmware, but here's the inxi output:

Code: Select all

$ inxi -n
Network:   Card: Intel 82579LM Gigabit Network Connection driver: e1000e
           IF: eno1 state: up speed: 100 Mbps duplex: full
           mac: --:--:--:--:--:--
Ah, didn't see that earlier.
The isohybrid method did not work for some reason, but mouting the ISO and running the script from the root path of the image produced a bootable pendrive.
However sadly, the connection is unstable in SystemRescueCD too...

Dai_trying
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Re: Unstable LAN wired connection

#9 Post by Dai_trying »

andoru wrote:

Code: Select all

$ inxi -n
Network:   Card: Intel 82579LM Gigabit Network Connection driver: e1000e
           IF: eno1 state: up speed: 100 Mbps duplex: full
           mac: --:--:--:--:--:--
That appears to be using the correct driver/firmware so I cannot offer much more help I'm afraid, what I would try though is a live-Cd of a distro based on Buster to see if it happens with the testing version or if it might have updated versions which fix your issue. Sorry I couldn't help more but I hope you find a fix.

Segfault
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Re: Unstable LAN wired connection

#10 Post by Segfault »

The MAC address is not showing, there is something broken in hardware or BIOS/firmware.

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Re: Unstable LAN wired connection

#11 Post by Dai_trying »

Segfault wrote:The MAC address is not showing, there is something broken in hardware or BIOS/firmware.
I must admit I thought OP removed it for privacy reasons but I agree it could be an issue. It might be worth getting the latest firmware from the Intel site to see if that works better...

Segfault
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Re: Unstable LAN wired connection

#12 Post by Segfault »

There cannot be any privacy issues with ethernet MAC address, it is a Layer 2 attribute, it is used only on LAN.

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Re: Unstable LAN wired connection

#13 Post by p.H »

Dai_trying wrote:Also I noticed you mentioned something about gigabit connection in the reddit post which makes me think you might need the tg3 firmware which I believe is in the package firmware-misc-nonfree
andoru wrote:Network: Card: Intel 82579LM Gigabit Network Connection driver: e1000e
IF: eno1 state: up speed: 100 Mbps duplex: full
mac: --:--:--:--:--:--
Err, I seriously doubt that this Intel NIC needs any tg3 (Broadcom) firmware.
Is it the output "as is" or did you hide the MAC address ? Please don't, or at least leave the first 3 bytes (manufacturer's OUI) untouched.
Dai_trying wrote:you can always disable the non-free repository once you have the required firmware
Why would you want to do this ? What about security updates ?
Segfault wrote:There cannot be any privacy issues with ethernet MAC address, it is a Layer 2 attribute, it is used only on LAN.
You're wrong. MAC addresses can appear in autoconfigured global (ie public and routable) IPv6 addresses.

By the way, has anyone suggested to check related messages in the kernel logs ?

Segfault
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Re: Unstable LAN wired connection

#14 Post by Segfault »

You saying the MAC address of my NIC will be seen after umpteen hops on the internet when using IPv6?

BTW, PCI ID is much better identifier when in comes to hardware identification. By PCI ID you can grep the kernel sources or search the kernel driver database at cateee.net.

Example:

Code: Select all

00:1f.6 Ethernet controller [0200]: Intel Corporation Ethernet Connection (2) I219-V [8086:15b8] (rev 31)
Heading over to cateee.net I can see the driver for my NIC 8086:15b8 has been in the kernel since kernel version 4.1.

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Re: Unstable LAN wired connection

#15 Post by p.H »

Segfault wrote:You saying the MAC address of my NIC will be seen after umpteen hops on the internet when using IPv6?
Yes, it may, depending on how the global IPv6 address assigned to the interface is generated.
Segfault wrote:BTW, PCI ID is much better identifier when in comes to hardware identification.
MAC address and PCI ID do not have the same purpose at all.
PCI ID is more like a part number.
MAC address is more like a serial number.

Segfault
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Re: Unstable LAN wired connection

#16 Post by Segfault »

Segfault wrote:BTW, PCI ID is much better identifier when in comes to hardware identification.
MAC address and PCI ID do not have the same purpose at all.
PCI ID is more like a part number.
MAC address is more like a serial number.
I never said they have same purpose. You said it would be nice to have first 3 bytes to see the manufacturer.

I'm going to read up on IPv6 now. Even if you are right I still see no privacy issue.

andoru
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Re: Unstable LAN wired connection

#17 Post by andoru »

Dai_trying wrote:I must admit I thought OP removed it for privacy reasons but I agree it could be an issue.
That is correct, I redacted the MAC address for privacy concerns
Dai_trying wrote:It might be worth getting the latest firmware from the Intel site to see if that works better...
I did that, compiled the driver, removed the one that came with the distro and made sure it was removed from cache too (with update-intramfs -u), made sure the latest version is used with modinfo (it should be 3.4.0.2), and rebooted just in case the old drivers weren't properly flushed. Unfortunately, the connection is just as unstable as before.
p.H wrote:Is it the output "as is" or did you hide the MAC address ? Please don't, or at least leave the first 3 bytes (manufacturer's OUI) untouched.
No, as I mentioned above, the MAC address was redacted by me.
Here's the first three bytes of the address: 3c:d9:2b:--:--:--
p.H wrote:By the way, has anyone suggested to check related messages in the kernel logs ?
Let me know what you want me to look for, and what commands to use.
Segfault wrote: BTW, PCI ID is much better identifier when in comes to hardware identification. By PCI ID you can grep the kernel sources or search the kernel driver database at cateee.net.
Here you go:

Code: Select all

# lspci -vvv -n -s 00:19.0
00:19.0 0200: 8086:1502 (rev 04)
	Subsystem: 103c:1494
	Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR+ FastB2B- DisINTx+
	Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
	Latency: 0
	Interrupt: pin A routed to IRQ 30
	Region 0: Memory at fe400000 (32-bit, non-prefetchable) [size=128K]
	Region 1: Memory at fe428000 (32-bit, non-prefetchable) [size=4K]
	Region 2: I/O ports at f080 [size=32]
	Capabilities: [c8] Power Management version 2
		Flags: PMEClk- DSI+ D1- D2- AuxCurrent=0mA PME(D0+,D1-,D2-,D3hot+,D3cold+)
		Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=1 PME-
	Capabilities: [d0] MSI: Enable+ Count=1/1 Maskable- 64bit+
		Address: 00000000fee002f8  Data: 0000
	Capabilities: [e0] PCI Advanced Features
		AFCap: TP+ FLR-
		AFCtrl: FLR-
		AFStatus: TP-
	Kernel driver in use: e1000e
	Kernel modules: e1000e
Last edited by andoru on 2018-04-13 16:34, edited 1 time in total.

Segfault
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Re: Unstable LAN wired connection

#18 Post by Segfault »

It always pays off to address the problem and use common sense.
Which is not the case here.
We know now the proper driver is loaded, thus all the talk about identifying the hardware and finding correct driver is empty talk.
Then the output of a command was intentionally mangled leading us in wrong direction. There is no privacy issues publishing your MAC address. And even if there was stripping the info should have been mentioned.
Useful info we know:
The cable is proven good.
The connector was inspected, no fault found.
Potentially useful info not seen:
Output of ethtool -S.
Whether the latest firmware has been flashed in or not.

shep
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Re: Unstable LAN wired connection

#19 Post by shep »

I'll mention that your problem could be in router rather than your client.

I had a problem with dropped Static IP/DHCP connections that was actually caused by the router. The connection "leases" are renewed periodically and may fail during renewal. My router was flashed with OpenWRT/LEDE firmware but my understanding is that it was an Atheros/SoC IPV6 issue with the router hardware. My ISP still uses IPV4 and my LAN is IPV4, so I disabled IPV6 in the router and the problem went away.

andoru
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Re: Unstable LAN wired connection

#20 Post by andoru »

Segfault wrote:It always pays off to address the problem and use common sense.
Which is not the case here.
And by that you mean?
Segfault wrote:And even if there was stripping the info should have been mentioned.
Alright, my bad.

Segfault wrote:Potentially useful info not seen:
Output of ethtool -S.
Whether the latest firmware has been flashed in or not.
Well, I ran that command, but that only shows the session statistics for the NIC, here you go:

Code: Select all

# ethtool -S eno1
NIC statistics:
     rx_packets: 975
     tx_packets: 1913
     rx_bytes: 198426
     tx_bytes: 799058
     rx_broadcast: 99
     tx_broadcast: 19
     rx_multicast: 42
     tx_multicast: 204
     rx_errors: 0
     tx_errors: 0
     tx_dropped: 0
     multicast: 42
     collisions: 0
     rx_length_errors: 0
     rx_over_errors: 0
     rx_crc_errors: 0
     rx_frame_errors: 0
     rx_no_buffer_count: 0
     rx_missed_errors: 0
     tx_aborted_errors: 0
     tx_carrier_errors: 0
     tx_fifo_errors: 0
     tx_heartbeat_errors: 0
     tx_window_errors: 0
     tx_abort_late_coll: 0
     tx_deferred_ok: 0
     tx_single_coll_ok: 0
     tx_multi_coll_ok: 0
     tx_timeout_count: 0
     tx_restart_queue: 0
     rx_long_length_errors: 0
     rx_short_length_errors: 0
     rx_align_errors: 0
     tx_tcp_seg_good: 0
     tx_tcp_seg_failed: 0
     rx_flow_control_xon: 0
     rx_flow_control_xoff: 0
     tx_flow_control_xon: 0
     tx_flow_control_xoff: 0
     rx_csum_offload_good: 636
     rx_csum_offload_errors: 0
     rx_header_split: 0
     alloc_rx_buff_failed: 0
     tx_smbus: 1
     rx_smbus: 168
     dropped_smbus: 0
     rx_dma_failed: 0
     tx_dma_failed: 0
     rx_hwtstamp_cleared: 0
     uncorr_ecc_errors: 0
     corr_ecc_errors: 0
     tx_hwtstamp_timeouts: 0
     tx_hwtstamp_skipped: 0
It's weird how it doesn't mention any dropped packets or errors/failures, as I went through a lot of dropped packets and connection timeouts during the session.

I'll assume you meant ethtool -i, since that displays firmware info for the interface:

Code: Select all

# ethtool -i eno1
driver: e1000e
version: 3.4.0.2-NAPI
firmware-version: 0.13-4
expansion-rom-version: 
bus-info: 0000:00:19.0
supports-statistics: yes
supports-test: yes
supports-eeprom-access: yes
supports-register-dump: yes
supports-priv-flags: no
shep wrote: The connection "leases" are renewed periodically and may fail during renewal.
You mean DHCP binding? I do have all the PCs in the network assigned a static LAN IP bound to their MAC addresses in the router. Not sure if this is what you mean.
shep wrote:My ISP still uses IPV4 and my LAN is IPV4, so I disabled IPV6 in the router and the problem went away.
My ISP does use IPv6, and it works on the other PCs on the LAN, so I'm not sure. I also can't seem to find a way of disabling IPv6 in the router settings... :/

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