network connection often lost

[Lentes, Bernd]

----- 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
          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.


Bernd
 

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