network connection often lost
Lentes, Bernd
bernd.lentes at helmholtz-muenchen.de
Tue Oct 11 14:41:18 UTC 2016
----- Am 10. Okt 2016 um 20:20 schrieb Bernd Lentes bernd.lentes at helmholtz-muenchen.de:
> ----- On Oct 10, 2016, at 3:54 PM, Karl Auer kauer at biplane.com.au wrote:
>
>> On Mon, 2016-10-10 at 15:38 +0200, Lentes, Bernd wrote:
>>> i have two ubuntu boxes: 16.04.1 LTS and 12.04.2 LTS.
>>> Both are loosing network from time to time.
>>
>> When one of the two is working, save the outputs from "ip addr show"
>> and "ifconfig". Then when it stops working (loses connection) capture
>> the outputs again. Send us both sets.
>>
>> Are you using IPv4 or IPv6? Or both? Are both systems in the same
>> subnet?
>>
>> Does this happen even while data is being actively transferred, or only
>> if you leave them be for a while? How long does it take before the
>> problem occurs - is it regular?
>>
>> Regards, K.
>>
>
> Hi Karl,
>
> we use IPv4. Not in the same subnet. I have the impression that it happens
> while no or just a bit data is transfered. As i said, i loose existing ssh
> connctions,
> but not when i'm using them, but when i don't use them.
> Although i think there is still a bit traffic like keep-alives ...
> I can't say how long it takes, i experienced loss already maybe half an hour
> after
> login. Until now i couldn't recognize any rhythm.
>
>
> This host has currently connection:
>
> root at PC62470:~# cat /etc/os-release
> NAME="Ubuntu"
> VERSION="12.04.2 LTS, Precise Pangolin"
> ID=ubuntu
> ID_LIKE=debian
> PRETTY_NAME="Ubuntu precise (12.04.2 LTS)"
> VERSION_ID="12.04"
>
> root at PC62470:~# ifconfig
> eth0 Link encap:Ethernet HWaddr bc:ee:7b:5d:ed:54
Now it has no connection, which means i can't ping it or connect with ssh.
> inet addr:10.35.23.16 Bcast:10.35.23.255 Mask:255.255.255.0
> inet6 addr: fe80::beee:7bff:fe5d:ed54/64 Scope:Link
> UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
> RX packets:99810423 errors:0 dropped:0 overruns:0 frame:0
> TX packets:84674472 errors:0 dropped:0 overruns:0 carrier:0
> collisions:0 txqueuelen:1000
> RX bytes:7390181641 (7.3 GB) TX bytes:127587678438 (127.5 GB)
>
> lo Link encap:Local Loopback
> inet addr:127.0.0.1 Mask:255.0.0.0
> inet6 addr: ::1/128 Scope:Host
> UP LOOPBACK RUNNING MTU:16436 Metric:1
> RX packets:3 errors:0 dropped:0 overruns:0 frame:0
> TX packets:3 errors:0 dropped:0 overruns:0 carrier:0
> collisions:0 txqueuelen:0
> RX bytes:264 (264.0 B) TX bytes:264 (264.0 B)
>
> root at PC62470:~# ip addr show
> 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN
> link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
> inet 127.0.0.1/8 scope host lo
> inet6 ::1/128 scope host
> valid_lft forever preferred_lft forever
> 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP
> qlen 1000
> link/ether bc:ee:7b:5d:ed:54 brd ff:ff:ff:ff:ff:ff
> inet 10.35.23.16/24 brd 10.35.23.255 scope global eth0
> inet6 fe80::beee:7bff:fe5d:ed54/64 scope link
> valid_lft forever preferred_lft forever
>
>
> The other host (also with connection):
>
> root at pc65472:~# cat /etc/os-release
> NAME="Ubuntu"
> VERSION="16.04.1 LTS (Xenial Xerus)"
> ID=ubuntu
> ID_LIKE=debian
> PRETTY_NAME="Ubuntu 16.04.1 LTS"
> VERSION_ID="16.04"
> HOME_URL="http://www.ubuntu.com/"
> SUPPORT_URL="http://help.ubuntu.com/"
> BUG_REPORT_URL="http://bugs.launchpad.net/ubuntu/"
> UBUNTU_CODENAME=xenial
> root at pc65472:~#
> root at pc65472:~#
> root at pc65472:~# ifconfig
> enp0s31f6 Link encap:Ethernet HWaddr 90:1b:0e:8f:1b:67
> inet addr:10.35.34.125 Bcast:10.35.34.255 Mask:255.255.255.0
> inet6 addr: fe80::dd2:9f41:7c2b:c7a8/64 Scope:Link
> UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
> RX packets:1068468 errors:0 dropped:2 overruns:0 frame:0
> TX packets:28494 errors:0 dropped:0 overruns:0 carrier:0
> collisions:0 txqueuelen:1000
> RX bytes:126530560 (126.5 MB) TX bytes:6179320 (6.1 MB)
> Interrupt:16 Memory:f7000000-f7020000
>
> lo Link encap:Local Loopback
> inet addr:127.0.0.1 Mask:255.0.0.0
> inet6 addr: ::1/128 Scope:Host
> UP LOOPBACK RUNNING MTU:65536 Metric:1
> RX packets:3947 errors:0 dropped:0 overruns:0 frame:0
> TX packets:3947 errors:0 dropped:0 overruns:0 carrier:0
> collisions:0 txqueuelen:1
> RX bytes:562550 (562.5 KB) TX bytes:562550 (562.5 KB)
>
> root at pc65472:~#
> root at pc65472:~#
> root at pc65472:~# ip addr show
> 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group
> default qlen 1
> link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
> inet 127.0.0.1/8 scope host lo
> valid_lft forever preferred_lft forever
> inet6 ::1/128 scope host
> valid_lft forever preferred_lft forever
> 2: enp0s31f6: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state
> UP group default qlen 1000
> link/ether 90:1b:0e:8f:1b:67 brd ff:ff:ff:ff:ff:ff
> inet 10.35.34.125/24 brd 10.35.34.255 scope global dynamic enp0s31f6
> valid_lft 250510sec preferred_lft 250510sec
> inet6 fe80::dd2:9f41:7c2b:c7a8/64 scope link
> valid_lft forever preferred_lft forever
>
>
> When one looses connection i will provide you with the desired information.
Now it lost connection. Because it's not a graphical environment i could not
copy and paste, so i made a real screenshot.
Find it here: https://hmgubox.helmholtz-muenchen.de:8001/f/fddd5371c0/?raw=1
For me everything looks ok. ethtool says is detects a link.
The adapter seems to be up. But i can't ping it.
OMG. I just went to the box and it answers now to pings.
I didn't change anything, just made the three commands you see in the photo.
I don't have any idea.
William, i think it's not the switch because the two hosts i have the proplem with
are attached to different switches.
Bernd
Helmholtz Zentrum Muenchen
Deutsches Forschungszentrum fuer Gesundheit und Umwelt (GmbH)
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