Pl use below commmands to get the details about packet loss.
"show system statistics" will show you drops in RE due to no buffers/TCP auth errors/rate limit/no socket etc
"show pfe statistics error" will show you drops inside PFE ASIC
"show pfe statistics traffic" will show you drops due to no matching route (normal discard)
"show interface queue <interface-id>" will show you RED drops and tail drops in both egress and ingress queues (if ingress queues are supported on the HW used).
"show interface <interface-id> media detail" will show you drops due to SA/DA MAC filtering; FIFO, CRC errors etc.
and also reference
http://www.juniper.net/techpubs/en_US/junos14.2/topics/concept/using-show-commands-for-packet-drops.html
https://kb.juniper.net/InfoCenter/index?page=content&id=KB28175&smlogin=true
http://www.juniper.net/techpubs/en_US/junos11.4/information-products/topic-collections/security/software-all/monitoring-and-troubleshooting/index.html?jd0e24088.html