Datasheet

Configuring Voice Ports
Configuring Digital Voice Ports
VC-69
Cisco IOS Voice, Video, and Fax Configuration Guide
controller E1 1/1 << description - connected to the PBX
framing crc4
linecoding hdb3
clock source line
ds0-group timeslots 1-15 type e&m-wink-start
The clock source line primary command tells the router to use this voice port to drive the PLL. All
other voice ports configured as clock source line are then put into an implicit loop-timed mode. If
the primary voice port fails or goes down, the other voice port instead receives the clock that drives
the PLL. In this configuration, port 1/1 might see controlled slips, but these should not force it down.
This method prevents the PBX from seeing slips.
Note When terminating two T1/E1 lines on a two-port interface card, such as the VWIC-2MFT, if
both controllers are set for line clocking but the lines are not within clocking tolerance of one
another, one of the controllers is likely to experience slips. To prevent slips, ensure that the
two T1/E1 lines are within clocking tolerance of one another, even if the lines are from
different providers.
• Dual Voice Ports (One Receives Clocking and One Provides Clocking)—In this scenario, the digital
voice hardware receives clocking for the PLL from E1 0 and uses this clock as a reference to clock
E1 1 (see Figure 20). If controller E1 0 fails, the PLL internally generates the clock reference to
drive E1 1.
Figure 20 Dual E1 ports—One Receiving and One Providing Clocking
The following configuration sets up this clocking method:
controller E1 1/0
framing crc4
linecoding hdb3
clock source line
ds0-group timeslots 1-15 type e&m-wink-start
!
controller E1 1/1
framing crc4
linecoding hdb3
clock source internal
ds0-group timeslots 1-15 type e&m-wink-start
E1 0
E1 1
Clock
Clock
26922
PSTN
PBX