[nycbug-talk] Can RTSP and dumb switches coexist?

Miles Nordin carton at Ivy.NET
Thu Oct 18 10:42:39 EDT 2007

>>>>> "ap" == Alex Pilosov <alex at pilosoft.com> writes:

    ap> b) dumb switches *must* comply with 802.1d (the STP protocol)
    ap> anyway.

there are some, i dunno, ``moronic'' switches that don't even do that.
The ones I've seen are ones without fans: the 4-port switch in the
back of the PIX 501, and some 8-port 3com gigabit switch.  When I
plugged a loopback cable between port 1 and 2 on these switches, they
looped and stormed and went nuts.

The problem someone told me about was, users buy them to use in their
cubicles, end up with spaghetti cables, and accidentally use a nest of
Moronic Switches to connect two wall ports into a loop.  I don't know
what happens in this case.  I would expect RSTP to detect it even with
'port-fast' on, and STP to detect it only with 'port-fast' off, but
I'm not sure.

And no matter what the expensive switches do, I think this is still a

   |                      |
   | dumb / smart switch  |-+
   |  STP or RSTP         |X|  <-- loud fan
     | ^
     | ^
     | | flooded garbage
     | ^
     |    +-+ <-- crossover cable
     |    | |
 | moronic switch |         +-+=
 +----------------+---------| |
                  wall wart ^^^
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