pls run a deep inspection on the packets at switch, especially on MAC encap. There will be a field that is creating an issue between the 2. You may not able to change this field as its specific to vendor, but you maybe able to identify the error field and will help you with the journey... HTHs. :-)

 

----------------------------------------
        |           IP delivery header         
        |        destination addr       
        |    IP proto = MAC type of the UDL    
           ----------------------------------------
         |            Payload packet            
         |             MAC packet               
           ----------------------------------------