multi-link CE-PE connections

hi,

what is recommended way to support/detect the following VPLS (mis)configuration. For simplicity assume Ethernet attachment circuits.

	-------------------------
	|  PE		|
	|		|
	------------------------
	 P1/	\ P2
	   /	 \
	------------------
	| HUB        |
	-----------------
	     |
	     |
	----------------
	|  CE	|
	--------------

1: it is a misconfiguration. don't do it
2: vendors are running proprietary link-level protocols to break the local loop (P1<->P2) at the PE. one of the ports (P1 or P2) is blocked at any one time..
3: what if it is not a misconfiguration but customers want to do this intentionally to provide redundant PE-CE links ?

Thank you

shanthi kiran
Luminous Networks
Cupertino CA