Cisco Cisco Packet Data Interworking Function (PDIF) Guía De Administador
System Settings
▀ Configuring Transmit Timing Source
▄ Cisco ASR 5000 System Administration Guide
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Configuring Transmit Timing Source
This feature is only for application services that use SDH or SONET over optical (OLC/OLC2) or channelized
(CLC/CLC2) line cards.
(CLC/CLC2) line cards.
In general, the SPIO automatically provides clocking based on the system clock. However, some application services
that use SDH or SONET require greater clocking precision to ensure synchronous transmission. The timing source
options include Building Integrated Timing Supply (BITS) and line-timing.
that use SDH or SONET require greater clocking precision to ensure synchronous transmission. The timing source
options include Building Integrated Timing Supply (BITS) and line-timing.
BITS-timing accepts external clock signals from a BITS source that relies on Stratum 1 or GPS timing signals for high
accuracy.
accuracy.
Line-timing recovers the transmit timing from a specified port on an OLC/OLC2 or CLC/CLC2. This method of timing
requires that the SPIO be equipped with the optional Stratum 3 clock module.
requires that the SPIO be equipped with the optional Stratum 3 clock module.
The timing is then distributed via the SPIO to all line cards in the chassis.
Important:
To use BITS-timing, the SPIO card must include the optional BITS E1 BNC or T1 (DS1)3-pin
timing interface. For additional interface information, refer to the ASR 5000 Installation Guide.
You can enable and configure up to four timing sources: two BITS-timing and two line-timing sources. Having more
than one timing source assures redundancy. When enabled BITS-timing always takes priority over line-timing for
system clocking.
than one timing source assures redundancy. When enabled BITS-timing always takes priority over line-timing for
system clocking.
Configure BITS as the Timing Source
Use the following example to configure BITS as the timing source:
configure
port bits slot#/port#
mode {e1|t1} framing type
no shutdown
end
For additional information, refer to the BITS Port Configuration Mode Commands chapter of the Command Line
Interface Reference.
Interface Reference.
Save the configuration according to the steps in Verifying and Saving Your Configuration.