We are seeing clock slips on t1 controller that is set for line clock primary. Show controller t1 indicates " Current port master clock: unknown".
Hardware/IOS is : System image file is "flash:c3640-js-mz.122-3.bin"
cisco 3640 (R4700) processor (revision 0x00) with 122880K/8192K bytes of memory.
We have several remote sites that are seeing the same thing, so we don't think it is a bad piece of hardware. Don't understand why port master clock is unknown, it should be recovered from line.
T1 link is over a satellite shot. The satellite modem at the remote sites recovers clock from the satellite side and slaves the side going to the router. All that looks good.
Any help or ideas appreciated...