[GRLUG] Ubiquiti issues

Adam Tauno Williams awilliam at whitemice.org
Tue Sep 9 16:17:56 EDT 2014

On Tue, 2014-09-09 at 15:52 -0400, Benjamin Flanders wrote: 
> Question:
> What would cause a client to be randomly unable to access or ping a
> certain server on the network, while other clients have no issue
> pinging said server, nor does that client have an issue pinging other
> servers.  It isn't just this laptop, I've witnessed this directly one
> other time a few weeks ago.

A bad switch, wigging out spanning-tree configuration, a bad switch,
overlapping MAC#s on the network, a bad switch, or a switch whose table
has overflowed [hard to believe these days]. 
> Background:
> Today I had a sales manager come to me saying that his internet was
> going up and down all morning, but he has had a strong connection the
> whole time(from the little icon in the system tray).  It was currently
> down so went over there and found that I couldn't ping the dns server,

Do you use managed switches?  Do you see errors of any kind?  Do they
report issues to a trap collector [an NMS?]?  If you have modern managed
switches they are likely trying very hard to tell you what the problem
> Mmm, I thought, I have wireshark at my desk on the other side of the
> office(as if I knew how to use it).  So I grabbed his laptop and went
> to my office.  Alas, when I got to my desk the laptop was not having
> any issues with pinging the dns server anymore.  I don't know if it
> was crossing into another AP (reconnecting to network), or just that
> it randomly started working.

Do you see errors?  Whatever the Windows equivalent of "netstat -i" is.

> Once I get the DHCP server on the linux box I'll truely see if my
> issue stops being getting an IP lease and starts to becoming a DNS
> issue.

I'd wager it is neither. 
Adam Tauno Williams <mailto:awilliam at whitemice.org> GPG D95ED383
Systems Administrator, Python Developer, LPI / NCLA

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