Ethernet down a few times per day

English Network/Internet
1

Hi all,
I’m having a “weird” problem… the ethernet connections in one machine are going down a few times per day. They get up again soon after, but this is not so great.
Ideas? This is not critical, but not great, and I would like to understand the issue and fix it.
Thanks!

details:
openSUSE Leap 15.5
Linux 5.14.21-150500.55.52-default #1 SMP PREEMPT_DYNAMIC Tue Mar 5 16:53:41 UTC 2024 (a62851f) x86_64 x86_64 x86_64 GNU/Linux

Network:
Device-1: Intel Ethernet I219-LM driver: e1000e
IF: eth1 state: up speed: 1000 Mbps duplex: full mac:
Device-2: Intel I210 Gigabit Network driver: igb
IF: eth0 state: up speed: 1000 Mbps duplex: full mac:

the network connections are configured with wicked using DHCP (always receiving the same IPs addresses)

# dmesg -T | egrep "Link is [D|U]"
[Mon Apr  8 23:30:48 2024] igb 0000:02:00.0 eth0: igb: eth0 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: RX/TX
[Mon Apr  8 23:30:48 2024] e1000e 0000:00:1f.6 eth1: NIC Link is Up 1000 Mbps Full Duplex, Flow Control: Rx/Tx
[Tue Apr  9 08:05:42 2024] igb 0000:02:00.0 eth0: igb: eth0 NIC Link is Down
[Tue Apr  9 08:05:42 2024] e1000e 0000:00:1f.6 eth1: NIC Link is Down
[Tue Apr  9 08:05:48 2024] igb 0000:02:00.0 eth0: igb: eth0 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: RX/TX
[Tue Apr  9 08:05:52 2024] e1000e 0000:00:1f.6 eth1: NIC Link is Up 1000 Mbps Full Duplex, Flow Control: Rx/Tx
[Tue Apr  9 10:03:16 2024] e1000e 0000:00:1f.6 eth1: NIC Link is Down
[Tue Apr  9 10:03:20 2024] e1000e 0000:00:1f.6 eth1: NIC Link is Up 1000 Mbps Full Duplex, Flow Control: Rx/Tx
[Tue Apr  9 15:05:42 2024] e1000e 0000:00:1f.6 eth1: NIC Link is Down
[Tue Apr  9 15:05:42 2024] igb 0000:02:00.0 eth0: igb: eth0 NIC Link is Down
[Tue Apr  9 15:05:50 2024] igb 0000:02:00.0 eth0: igb: eth0 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: RX/TX
[Tue Apr  9 15:05:55 2024] e1000e 0000:00:1f.6 eth1: NIC Link is Up 1000 Mbps Full Duplex, Flow Control: Rx/Tx
[Tue Apr  9 20:05:41 2024] igb 0000:02:00.0 eth0: igb: eth0 NIC Link is Down
[Tue Apr  9 20:05:42 2024] e1000e 0000:00:1f.6 eth1: NIC Link is Down
[Tue Apr  9 20:05:50 2024] igb 0000:02:00.0 eth0: igb: eth0 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: RX/TX
[Tue Apr  9 20:05:52 2024] e1000e 0000:00:1f.6 eth1: NIC Link is Up 1000 Mbps Full Duplex, Flow Control: Rx/Tx
[Wed Apr 10 05:47:08 2024] e1000e 0000:00:1f.6 eth1: NIC Link is Down
[Wed Apr 10 05:47:08 2024] igb 0000:02:00.0 eth0: igb: eth0 NIC Link is Down
[Wed Apr 10 05:47:15 2024] igb 0000:02:00.0 eth0: igb: eth0 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: RX/TX
[Wed Apr 10 05:47:19 2024] e1000e 0000:00:1f.6 eth1: NIC Link is Up 1000 Mbps Full Duplex, Flow Control: Rx/Tx
[Wed Apr 10 05:58:54 2024] e1000e 0000:00:1f.6 eth1: NIC Link is Down
[Wed Apr 10 05:58:54 2024] igb 0000:02:00.0 eth0: igb: eth0 NIC Link is Down
[Wed Apr 10 05:59:03 2024] igb 0000:02:00.0 eth0: igb: eth0 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: RX/TX
[Wed Apr 10 05:59:04 2024] e1000e 0000:00:1f.6 eth1: NIC Link is Up 1000 Mbps Full Duplex, Flow Control: Rx/Tx
[Wed Apr 10 19:55:15 2024] e1000e 0000:00:1f.6 eth1: NIC Link is Down
[Wed Apr 10 19:55:20 2024] e1000e 0000:00:1f.6 eth1: NIC Link is Up 1000 Mbps Full Duplex, Flow Control: Rx/Tx
[Thu Apr 11 00:58:52 2024] igb 0000:02:00.0 eth0: igb: eth0 NIC Link is Down
[Thu Apr 11 00:58:52 2024] e1000e 0000:00:1f.6 eth1: NIC Link is Down
[Thu Apr 11 00:58:58 2024] igb 0000:02:00.0 eth0: igb: eth0 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: RX/TX
[Thu Apr 11 00:59:04 2024] e1000e 0000:00:1f.6 eth1: NIC Link is Up 1000 Mbps Full Duplex, Flow Control: Rx/Tx
[Thu Apr 11 03:58:52 2024] igb 0000:02:00.0 eth0: igb: eth0 NIC Link is Down
[Thu Apr 11 03:58:52 2024] e1000e 0000:00:1f.6 eth1: NIC Link is Down
[Thu Apr 11 03:58:58 2024] igb 0000:02:00.0 eth0: igb: eth0 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: RX/TX
[Thu Apr 11 03:59:02 2024] e1000e 0000:00:1f.6 eth1: NIC Link is Up 1000 Mbps Full Duplex, Flow Control: Rx/Tx
 #
2

I would be checking the cabling and termination, as well as other connected network appliances (including logs).

3

It is very unlikely that this is a hardware/cabling problem because this machine has two network adapters, two ethernet high quality cables (they are in fact different, one CAT-6 and another CAT-7 cable). And both eth0 + eth1 are having the same problem at the same time:

20:05:41 ] igb .. eth0 NIC Link is Down
20:05:42 ] e1000e .. eth1: NIC Link is Down
...
20:05:50 ] igb .. eth0 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: RX/TX
20:05:52 ] e1000e .. eth1: NIC Link is Up 1000 Mbps Full Duplex, Flow Control: Rx/Tx

I’m much more inclined to a software configuration problem… but I’m yet to find clear evidence. I could try to put the network in debug mode…

4

I am with @deano_ferrari that this looks more like a hardware problem.

For the log, grepping for the problem is good but once you found it, check for all relevant messages around the time the problem happened.

5

The problem seems to be caused by a firewall that is blocking some DHCP packets regarding renewal of leases. And as it seems, after some retries, the links go down and up again in order to “restart” the lease process… sending a discovery request and so on.
Investigation ongoing :slight_smile:

6

Select “auto negotiate” in settings for speed/standard selection.
Try to use non-Intel (Realtek) NIC.

7

The issue was caused by a network/firewall misconfiguration (that was blocking some DHCP packets) that in turn caused a router to “restart” the affected links. And this of course translated to a loss of network signal for some nodes (for a few seconds periodically).
Problem solved.

8

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