[ale] OT: ethernet port issues

[Boris Borisov]

We switched to different port on Cisco. Then on next visit we swapped PC
retaining the old hard drive. Unfortunately the Cisco is under control of
someone else and they claim cannot pull any logs only can see if MAC
address is on the port. Not really enough or they are lazy.

Same with cable not under my control.

I guess I can try spray contact cleaner.

You know how companies work. Ball gets thrown around the field. Is not me
is you :)

On Sat, Jul 24, 2021, 15:34 Steve Litt via Ale <ale at ale.org> wrote:

> Solomon Peachy via Ale said on Sat, 24 Jul 2021 14:40:31 -0400
>
> >On Sat, Jul 24, 2021 at 02:27:26PM -0400, Boris Borisov via Ale wrote:
> >>  PC looses connectivity with Cisco switch. When I go to site there
> >> is no LED lit on PC ethernet port. Once I unplug and plug cable back
> >> connection is restored.
> >>
> >> Possible causes?
> >
> >flaky port on switch, flaky port on PC, flaky cable?
>
> Probably even more possible causes, but the preceding is a good start.
> Now is the time to start diagnostic tests. IMHO easiest test is to
> spray electronics lubricant on both ends of the cable and in the ports
> of the switch and PC. Either you'll get lucky and it was just a matter
> of contact oxidation, or you'll rule that out.
>
> My next step would be to try different ports on the switch and see if
> the symptom changes.
>
> My next step would be to swap the cable with a known good cable ---
> that's usually easy, even if instead of running it thru the wall you
> just temporarily tape it to the floor.
>
> >
> >I don't know what sort of logging the cisco switch has, but if the PC
> >is running Linux there might be something useful in the logs when the
> >connection drops.
>
> If the switch doesn't have logging, you can make your own logging by
> creating your own daemon, written as a shellscript, to ping -c1, a
> known active computer on your LAN every 10 seconds. You write the
> shellscript exactly as you'd write it if you were running it from the
> command prompt. Runit, s6, OpenRC and systemd can all run a daemon that
> doesn't background itself. If you're using sysvinit, either run/respawn
> runit or s6 from /etc/inittab, or do it with cron, but I think you'd
> be limited to 1 measurement per minute (please correct me if I'm
> wrong). The runit init run script would look something like this:
>
> =====================================
> #!/bin/sh
> exec /path/to/my/shellscript
> =====================================
>
> The shellscript itself would look like the following:
>
> =====================================
> #!/bin/sh
> while /bin/true; do
>    ping -c1  192.168.0.14 > /dev/null \
>    || date  "+%Y-%m-%d@%H:%M:%S" > /var/log/mylog.log
> done
> =====================================
>
> >
> >Oh, other possiblities: adminsistrative action/policies on either
> >side, plus the ever possible spectre of plain ol' software bugs.
>
> I'd run it overnight running a live CD with a distro as different from
> the installed distro as possible, running the daemon from a command
> prompt. In other words, swap operating systems.
>
> Also, run it from the installed OS, freshly rebooted, with no
> software running, overnight. That would tend to rule in or out software
> you run on top of your installed OS.
>
> SteveT
>
> Steve Litt
> Spring 2021 featured book: Troubleshooting Techniques of the Successful
> Technologist http://www.troubleshooters.com/techniques
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