Re: announcement of ext DIP prefix in BGP

Have you tried proxy ARP for the return traffic, check if this helps.

set interface interface proxy-arp-entry <ip_min> <ip_max>
unset interface interface proxy-arp-entry <ip_min> <ip_max>

http://kb.juniper.net/InfoCenter/index?page=content&id=KB17881&smlogin=true&actp=search

Thanks,

VIkas