If you have 3 spare (lab) switches just hook them up in the classic triangle where there are all hooked togther with a single patch, this is a classic redundancy setup that people use , with it is a built in loop that STP will prevent the loop on , somewhere within that setup you will see a blocked port thus eliminating the loop.
If you use the "spanning-tree bpdufilter enable" interface command on the trunk ports connecting the 2950 switches you will effectively disable spanning-tree on those ports.
As result of this, your switches will not be protected against the loop. Just put any broadcast frame into an access port and you will see the trunk ports blinking continuously, indicating the looped traffic.
If you issue the "show spanning-tree" command, you will not see blocked ports.
Probably you will have a difficulty of access to the console port as well, but you can break the loop by disconnecting a trunk cable.
Now if you issue the "spanning-tree bpdufilter disable" on the trunk ports, you will see that the spanning-tree algorithm works again and you will have one or more blocked ports.
This is actually a pretty cool feature, i didn't even know it existed until I was looking for a solution to advertise a subnet (prefix in BGP talk), only if a certain condition existed. This is exactly what conditional advertisements does
j ai une question j ai achete un routeur cisco 887VA-k9 , je le configuré avec la configuration ci- dessous
si je le lier avec mon pc portable sur l un de ses ports directement ça marche toute est bien ( la connexion internet + m...
Attached policy provides CLI access to the Cisco 4G router over text messaging. Two files are in the attached .tar file:
2. PDF with instructions on how to load and use the .tcl file.