single cable connected to same switch.

[Jignesh1]

Hello Guys,

What will happen if we connect single cable on two different port (port 1 and port 2) of same switch.

1st condition

1-> both port are in same vlan 10 and PVST is working.

2->both port are in different vlan (10 & 20) and pvst is working.

2nd condition

1->on both port port fast  and bpdu gaurd is enabled.

my assumption are:

1st condition 

1-> it will not form loop. pvst will block one port

2-> it will form loop as both vlan will be having diferent stp instance and they       wont be able to know

2nd condition

1- it will not form loop as bpdu gaurd on one of port will drop the bpdu

can any one help on this

[dialerstring]

This wouldn't be a good thing as this could cause network instability in your environment.  This happened years ago at one of my remote offices and it caused problems. I'm assuming this is a lab.

[Jignesh1]

hi dialerstring,

Thanks for replying i am curious to know what will happen, not implementing anywhere.

What will be the output ??