Clocking mode is defined at the adapter card level. There are three clocking modes available: differential, adaptive, and dcr-acr, which is a mixture of both differential and adaptive. The dcr-acr option enables differential and adaptive clocking on different ports of the same card or chassis. Differential and dcr-acr clocking modes also support a configurable timestamp frequency. To carry differential clock recover information, the RTP header must be enabled on the SAP.
The following chassis, cards, and modules support all clocking modes:
16-port T1/E1 ASAP Adapter card
32-port T1/E1 ASAP Adapter card
7705 SAR-M (variants with T1/E1 ports)
7705 SAR-X
7705 SAR-A (variant with T1/E1 ports)
T1/E1 ports on the 4-port T1/E1 and RS-232 Combination module
When the timestamp frequency is configured for differential or dcr-acr mode on a 4-port T1/E1 and RS-232 Combination module, the configured value takes effect on both modules installed in the 7705 SAR-H.
The following cards support differential clocking mode only:
4-port OC3/STM1 / 1-port OC12/STM4 Adapter card (DS1/E1 channels)
4-port DS3/E3 Adapter card (clear channel DS3/E3 ports and DS1/E1 channels on channelized DS3 ports (E3 ports cannot be channelized)); differential clocking mode on DS1/E1 channels is supported only on the first three ports of the card
Use the following CLI syntax to configure adaptive clocking mode.
config>card>mda#
clock-mode adaptive
no shutdown
Use the following CLI syntax to configure differential clocking mode or a combination of differential and adaptive clocking modes with a timestamp frequency.
config>card>mda#
clock-mode {differential | dcr-acr} [timestamp-freq {19440 | 25000 | 77760 | 103680}]
no shutdown