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Cisco AS5800 Universal Access Server Dial Shelf Card Guide
78-7097-03 0A
Chapter 3 Channelized T3 Trunk Card
CT1/CE1 Trunk Card Overview
Clocking
All Cisco AS5800 access server trunk cards use the same transmit clock. This clock can originate from
the following sources:
• TDM clock source—A priority value from 1 to 50 that is applied to a clock source when multiple
clock sources are used
• External clock source—A clock source external to the access server
Clocks are prioritized by slot number (slots 0 to 5). The highest-priority clock is selected from the card
in slot 0 and used as the default clock. If this clock fails, the highest-priority clock from the card in slot 1
becomes the default clock, and so forth.
The trunk card then forwards the clocks to the dial shelf controller. The dial shelf controller selects the
highest-priority clock as the system primary clock, and the rest of the clocks remain in a prioritized
backup queue.
Instead of using the default algorithm for clock selection, you can specify clocks through global
configuration and select a maximum of two clocks per trunk card.
If you configure fewer than two clocks on a trunk card and all other configured clocks fail, clock
selection resorts to the default algorithm on that card and the second clock will be selected automatically.
CT3 Clocking
CT1/CE1 trunk cards are usually attached to an external device, such as a Digital Access and
Crossconnect System (DACS) or Add-Drop Multiplexer (ADM). This point-to-point link requires a
single clock source to which the CT3 link is timed. You must determine whether you want the CT1/CE1
trunk card or an external device to be used as the primary clock source and configure it accordingly
during the software configuration process, which is discussed in the “Configuration Commands” section
on page 3-12.
CT1 Clocking
The CT1/CE1 trunk card has 28 T1 framers that always get their clock from the line. As a result,
configuration of T1 clock sources is not allowed.
LED and Alphanumeric Indicators
The CT1/CE1 trunk card front panel is designed with LED and alphanumeric displays to provide trunk
card status. (See Figure 3-3.)