Security problem in PPPoE connection

Hi, We are facing problem with PPPoE in ethernet access network. To provide high speed access, 10Mbps/100Mbps ethernet is used as access method. But, we found some guy 'steal' some other's account by listening to broadcasting packets, and they also set up 'phishing' PPPoE server to catch those PPPoE authentication packets. With ATM DSLAM,we could solve this by binding account with PVC. With ethernet, although we could seperate subscribers into VLANs there is more than 100 subscribers within one VLAN. What's your method to deal with such problem? Will CHAP in PPPoE help? thanks Joe __________________________________ Do you Yahoo!? Yahoo! Movies - Search movie info and celeb profiles and photos. http://sg.movies.yahoo.com/