Specifications

Configuring and Managing Cisco Access Servers and Dial Shelves
How to Configure Dial Shelves
DC-117
Cisco IOS Dial Technologies Configuration Guide
• Detection of component failures
• Error and warning messages
DSC redundancy provides maximum system availability by preventing loss of service if one of the DSCs
fails. There is no load sharing between the Broadband Inter-Carrier Interfaces (BICI). One BIC is used
as a backup, carrying only control traffic, such as keepalives, until there is a switchover.
Before starting this configuration task:
• Your Cisco AS5800 router shelf and dial shelf must be fully installed, with two DSC cards installed
on the dial shelf.
• Your Cisco AS5800 access server must be running Cisco IOS Release 12.1(2)T.
• The external DSC clocking port must be configured identically on both router shelves and must be
physically connected to both DSCs. This assures that if a DSC card needs replacing or if the backup
DSC card becomes primary, clocking remains stable.
Synchronizing to the System Clocks
The time-division multiplexing (TDM) bus in the backplane on the dial shelf must be synchronized to
the T1/E1 clocks on the trunk cards. The Dial Shelf Controller (DSC) card on the daily shelf provides
hardware logic to accept multiple clock sources as input and use one of them as the primary source to
generate a stable, PPL synchronized output clock. The input clock can be any of the following sources:
• Trunk port in slots 0 through 5—up to 12 can be selected (2 per slot)
• An external T1 or E1 clock source fed directly through a connector on the DSC card
• A free-running clock from an oscillator in the clocking hardware on the DSC card
For dual (redundant) DSC cards, the external DSC clocking port should be configured so that the clock
signal fed into both DSCs is identical.
To configure the external clocks, use the following commands from the router shelf login beginning in
global configuration mode. One external clock is configured as the primary clock source, and the other
is configured as the backup clock source.
Command Purpose
Step 1
Router(config)# dial-tdm-clock priority value
Configures the trunk card clock priority. Priority range is a
value between 1 and 50.
Step 2
Router(config)# dial-tdm-clock priority X
{trunk-slot Y port Z } external {t1 | e1}
[120-ohm]
Selects the T1/E1 trunk slot and port that is providing the
clocking source. T1/E1 selection is based on the incoming
signal. Select the impedance. The default impedance is
75-ohm.
Step 3
Router(config)# dial-tdm-clock priority value
external t1
or
Router(config)# dial-tdm-clock priority value
external e1
Configures the T1/E1 external clock on the dial shelf
controller front panel. T1/E1 selection is based on the signal
coming in. Priority range is a value between 1 and 50.
Step 4
Router(config)# Ctrl-Z
Router#
Verifies your command registers when you press the return
key. Enter Ctrl-Z to return to privileged EXEC mode.
Step 5
Router# copy running-config startup-config
Saves your changes.