i would still like to see output from "show route", "show arp no-resolve", "show ethernet-switching table" after trying to ping to see if layer2, arp and mac learning actually works.
Extra tests:
"monitor traffic interface irb.XXX no-resolve" to see if arp requests, ping requests and similar shows up.
Please provide the output from your tests. It's a lot easier to help when specific information is provided.
Which software version are you running on the SRX1500's?