In Junos, we can use RPM (real-time performance monitoring) to monitor link quality.

1. give a name to the ping probe and test name
   edit services rpm probe ping-probe test test-ping
2. set probe type
   set probe-type icmp-ping
3. set probe count for each test and interval between each ping (in second)
   set probe-count 10
   set probe-interval 1
4. set source and target address (must be the interconnect IPs if you want to detect link quality)
   set target address 192.168.1.1
   set source address 192.168.1.2
5. set the thresold for sucessful probe
   set thresolds total-loss 2
   set std-dev-rtt 50000
   where std-dev value is in micro second, not millisecond (1000 micro = 1 milli)

Optionional:

1. log the result in a remote monitoring (Syslog) server for generating alerts.
   top
   set system syslog host 172.168.0.1 daemon any
   set system syslog host 172.168.0.1 match rmopd
   where rmopd is the daemon name for ping probe