3Com 3031 Command Reference Manual page 197

Fundamental CT3 Interface Configuration Commands 197
The length of the cable for CT3 interface connection refers to the distance
between the router and the cable distribution rack.
Example
Set the cable length to 50 feet for the interface T3 1/0/0.
[3com-T3 1/0/0]cable 50
clock
Syntax
clock { master | slave }
undo clock
View
CT3 interface view
Parameter
master: Adopts the internal clock mode.
slave: Adopts the line clock mode.
Description
Using the clock command, you can set the clock mode on a CT3 interface. Using
the undo clock command, you can restore the default clock mode on the
interface.
By default, the CT3 interface adopts the line clock mode (slave).
The clock is selected depending on the connected remote device. If it is a
transmission device, the local end will use the line clock.
If the CT3 interfaces on the two routers are directly connected, one router should
use the internal clock whereas the other router uses the line clock.
Example
Configure the CT3 interface with internal clock.
[3com-T3 1/0/0]clock master
controller t3
Syntax
controller t3 interface-number
View
System view
Parameter
interface-number: CT3 interface number.