I have a core network in city A build based on two X440-24t connected in MSTP ring. I would like to connect my cisco switch located in city B through two Ethernet DWDM connections (provided by my ISPs) to my X440 (one link to each of X440). I would like to use MSTP to prevent loops (one link will be master and second one will be my backup). However there is still possibility that loops will occur (for instance in case of unidirectional connection caused by fiber failuer). Is there any option in Extreme like Loop guard from Cisco to prevent such situation?