Configuring Clocking; Trunk-Card Ports; External Clock - Cisco AS5350 - Universal Access Server Configuration Manual

Chapter 3 Basic Configuration Using the Command-Line Interface

Configuring Clocking

The time-division multiplexing (TDM) bus on the Cisco AS5350 and Cisco AS5400 backplane can
receive an input clock from one of four basic sources on the gateway:
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Building Integrated Timing Supply (BITS) is a single building master timing supply. BITS generally
Note
supplies DS1 and DS0 level timing throughout an office. In North America, BITS are the clocks that
provide and distribute timing to a wireline network's lower levels.

Trunk-Card Ports

The TDM bus can be synchronized with any trunk cards. On the CT1/CE1 trunk card, each port receives
the clock from the T1/E1 line. The CT3 trunk card uses an M13 multiplexer to receive the DS1 clock.
Each port on each trunk-card slot has a default clock priority. Also, clock priority is configurable through
the dial-tdm-clock priority CLI command.

External Clock

The TDM bus can be synchronized with an external clock source that can be used as an additional
network reference. If no clocks are configured, the system uses a primary clock through a
software-controlled default algorithm. If you want the external T1/E1 clock (via the BITs interface) as
the primary clock source, you must configure it using the dial-tdm-clock priority CLI command; the
external clock is never selected by default.
The BITs interface requires a T1 line composite clock reference set at 1.544 MHz and an E1 line
composite clock reference set at 2.048 MHz.
OL-3418-02 B0
CT1, CE1, and CT3 trunk cards
An external T1/E1 clock source feed directly through the Building Integrated Timing Supply (BITS)
interface port on the motherboard
Free-running clock providing clock from an oscillator
Cisco AS5350 and Cisco AS5400 Universal Gateway Software Configuration Guide
Configuring Clocking
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