I did some digging around and this is what I have found. IP unnumbered is not supported on the EX. If you try and configure it, this is themessage you get.
jp@EX-3200-1# show interfaces ge-0/0/18
unit 0 {
family inet {
##
## Warning: statement ignored: unsupported platform (ex3200-24t)
## Warning: referred interface must have address configured under family inet
##
unnumbered-address lo0.0;
}
}
After more searching, it doesn't look like this feature is on the roadmap either. If this is a feature you would like, please work with your SE to create an ehancement request (ER). Other folks are asking for this feature - so the more that ask the better the chance of having it developed for the EX.