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path ds1|e1 clock source
path ds1|e1 framing
Use the no version to remove the timeslots from the channel group.
See path ds1|e1 channel-group timeslots.
Use to configure the transmit clock source for the T1 or E1 interface.
Select a clock as follows:
Specify the keyword line to use a transmit clock recovered from the line's
receive data stream.
Specify the keywords internal module to use the line module's internal
clock.
Specify the keywords internal chassis to use the router's clock.
You can usually accept the default option, line, to use a transmit clock recovered
from the line's receive data stream, except in rare cases such as back-to-back
router tests. When performing back-to-back router tests, configure one end of
the line as internal and the other end as line.
On a cOC3/STM1 I/O module, you can configure some interfaces with internal
clock sources and others with line clock sources. However, all interfaces with
internal clock sources must use either the router's clock or the module's clock.
You cannot configure some interfaces on the I/O module to use the router's clock
and others to use the module's clock.
To change the clock source of the interfaces on a cOC3/STM1 I/O module from
the router's clock to the module's clock or vice versa, first change the clock
source of all ports to the line setting, and then to the new internal clock setting.
Example
host1(config-controll)#path 12 e1 1/4/1 clock source line
Use the no version to restore the default value, line.
See path ds1|e1 clock source.
Use to configure the framing format for a T1 or an E1 interface.
For T1, specify esf (extended superframe) or sf (superframe). The default is esf.
The HDLC idle character differs from non–E Series implementations. For T1
interfaces, if you configure SF, the router sets the HDLC idle character to 0xFF.
If you configure ESF, the router sets the HDLC idle character to 0x7E.
For E1, specify crc4 or no-crc4. The default is crc4.
Choose a framing format that is compatible with the framing format at the other
end of the line.
Example
host1(config-controll)#path 12 e1 1/4/1 framing no-crc4
Chapter 4: Configuring Channelized OCx/STMx Interfaces
Configuration Tasks
127
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