A dcr-serial parameter option is available on the 12-port Serial Data Interface card, version 3, to support the SAToP serial virtual channel (vc) type of Cpipe. The dcr-serial option can be configured using the serial>clock-source command; it is only supported on synchronous RS-232 and RS-530 interfaces. See the 7705 SAR Interface Configuration Guide, ‟Serial Commands”, for more information about how to configure DCR serial. See the 7705 SAR Services Guide, ‟SAToP Serial”, for information about SAToP serial.
During the normal transport of serial data traffic across a 7705 SAR IP/MPLS network, the time reference used to clock the data in/out of the 7705 SAR to the end device is based on the 7705 SAR system clock.
Some encryption applications, however, require both end devices on an encrypted link to run off the same time reference. To meet this requirement, the dcr-serial option is used to transport the system clock but only in a single direction: from the DTE-designated port of a SAToP serial Cpipe to the DCE-designated port at the other end. The source of the service clock is referenced to the Rx Clk signal of the DTE port on the 12-port Serial Data Interface card, version 3. One end of the a SAToP serial Cpipe must be set to DTE while the other end is set to DCE.
Only one clock can be transported per port.
The clock recovered by DCR serial is suitable only for clocking data into the attached device, not as a source of network synchronization.
The input frequency clock tolerance must within 4.5% of the configured port rate.
Although DCR serial is supported on 600 b/s port speeds, clock deviations from a nominal 600 b/s port speed are not supported. This applies to both RS-232 and RS-530 ports.
There can be a maximum of 12 DCR serial timing instances per 12-port Serial Data Interface card, version 3.