Unable to create loop

This post was last edited by mesbah at 2018-12-26 09:58. Please check if STP enabled :-

<HUAWEI> system-view


[HUAWEI] stp enable

# Edit STP, RSTP, MSTP, or VBST on GE1/0/1.
<HUAWEI> system-view
[HUAWEI] interface gigabitethernet 1/0/1
[HUAWEI-GigabitEthernet1/0/1] undo stp disable

@Skynet_india hello sir, if you mean you created a physic loop by connecting two ports to a hub, and the CPU usage is normal, please notice that MSTP is enabled by default on switch, this will make one of the interface under discarding state, if you wanna a real loop, you can try diable stp on the switch and send a broadcast packet into switch, by then, check the CPU usage, you should get a high CPU usage.
by the way, please DO NOT try this in real network.

Friend,

I have disabled the stp globally, but stil no traffic is passing on physically connected interfaces.

i have disabled stp globally, and checked the status " display stp brief " no interface is showing.

I have disabled the stp on a switch and created a loop using hub, but still no changes in cpu usage.

I am testing in ensp simulator.

@Skynet_india hello!

I've just tested and found it worked when I created a loop using hub. Please refer to my method.

Topology as per below:

Ping 10.1.11.2 (which can't exist in the topology) and capture the packets on the interface G0/0/2. In no more than 1 second, hundreds of thousands ARP request packets are captured, shown as below:

By the way, when the loop occurs, the CPU usage is 4%; the value is 1% with no loop.