Hey,
We are experiencing the same problems. We have a QFX5100 VC consisting of four members.
Currently, it behaves fairly unstable and we already had to reload it. We could ping servers connected to it from the outside but the servers could not ping out. There was not routing issue or something - seemed to be L2. :/ Pretty weird.
Has anyone of you already tried 15.1R4 or has some infos for a service release?