[CentOS] OT - odd behavior of Cisco switch

[m.roth at 5-cent.us]

Les Mikesell wrote:
> On Thu, Feb 7, 2013 at 10:53 AM,  <m.roth at 5-cent.us> wrote:
>> >>
>>> Have you actually configured the switch, or did you just plug it in and
>>> get running?
>>
>> Unfortunately, *we* don't control these switches. They're from the
>> networking division, which actually controls networking throughout the
>> campus. We've had them in, they claim they looked at the switches
>> remotely, and everything's wonderful.... We'll see what happens next
>> week,
>> when I do the next offline backups.
>>
>> Btw, we are on our own VLAN. The switch is on it.
>
> Is the traffic in question to something directly connected to this
> switch and just appearing mirrored to the wrong port or perhaps
> broadcast to all of them?   Or is the actual destination on some other
> switch where this one shouldn't even be in the path?   If you want to
> track the problem down you need to look backwards from the target and
> figure out why the switches in between did not learn the correct path.
>  It is not likely to be related to the traffic bandwidth unless some
> intermediate link is flooded to the point that nothing works.

Let's try ASCII art:
(campus net)->[vlan]->[new switch in rm. 1]-> server 1
                    \                      -> server 3
                     \->[switch in rm. 2]->server 2

And he was seeing traffic between 1 and 2 on 3. And he tried another
server in rm. 1, and saw it.

Does that make it clearer?

      mark