Connecting the T640 Router to an External Clocking Device

1. Attach an electrostatic discharge (ESD) grounding strap to your bare wrist, and connect the strap to one of the ESD points on the chassis.
2. Plug one end of the cable into the appropriate EXTERNAL CLOCK INPUTS port on the SCG.
3. Plug the other end of the cable into the T1 external clocking device.
4. Repeat the procedure for the other EXTERNAL CLOCK INPUTS port on the SCG.
5. Verify that the LINK LED for each port is lit steadily green.
6. Configure the port. See the synchronization statement for M Series and T Series in the Junos OS System Basics Configuration Guide .
7. Issue the show chassis synchronization command to check the status of the port.
   user@host> show chassis synchronization

   user@host> show chassis synchronization
   
       Clock Synchronization Status :
         Clock module on SCG 0
           Current state            : master
           Current clock state      : locked to external-a
             Selected for           : 2 hours, 28 minutes, 4 seconds
             Selected since         : 2006-02-17 01:12:58 PST
           Configured sources
             Source      Priority   Deviation    Last deviation   Status
                                    (in ppm)     (in ppm)
             external-a  primary    measuring    -0.10            in-use
             external-b  secondary  -0.10        -0.10            qualified
       Clock Synchronization Status :
         Clock module on SCG 1
           Current state            : backup
           Current clock state      : locked to master SCG
             Selected for           : 19 hours, 49 minutes, 14 seconds
             Selected since         : 2006-02-16 07:51:48 PST
           Configured sources
             Source      Priority   Deviation    Last deviation   Status
                                    (in ppm)     (in ppm)
             external-a  primary    -0.25        -0.25            qualified
             external-b  secondary  -0.25        -0.25            qualified