Switch stack cable

[Anukalp S]

Hi Experts.. need your input on a query.. " What will happen if we connect stack cable on same switch(from stack port1 to port2 same switch), will the switch go unresponsive OR will it function as normal" please suggest.

[balaji.bandi]

Its not suggest (its like you taking your Power Line and feed in to other socket of power - what is the outcome ? if you have breaker it trip - if not you have power outage and may be damage some electornic goods) - and its risk to damage switch or port.

Why do you want to do this  extreme practice ?

[Joseph W. Doherty]

Results likely depend on the platform.

Ideally, platform would "see" a self connected loop and block it.

If platform doesn't detect the self connected loop, results again, likely depend on the platform.  I would expect such results to possible be things like creating a L2 loop or perhaps needlessly sending data to the stack port to be ignored as it's received.

As an example of how platforms can differ, on the original 3750 series, switch placed all received frames on "ring" and source of frames removed by source switch member.  On such a switch, self connecting the two, same switch, stack ports might have no impact as switch is used to "seeing" all its frames returned to it.

On the later 3750X and -E models, they only placed unicast frames on the ring, as needed, and destination switch removed them.  So for unicast, at least, wouldn't expect switch's unicast frames to be sent out switch port.

However, for ether these two 3750 series, stack master election might be "confused" by seeing an "up" ring, but no other stack members.