i guess your question why connection between two 5500 is blocking as you expect them.
It is not as simple as that. It depends upon who the root is and the cost of getting to the root from the devices. In this case, the reason is probably because 3500XL is the root the SPT and link between A & B is blocking.
If you want to make the link go forwarding make one of the 5500 as the the root and now on of the link from the XL to the backup 5500 would block. Ofcourse there is COST of the links involved but i am assuming all links are equal.
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.