Understanding Channelized Interface Drop-and-Insert
On channelized T1/E1/ISDN PRI interfaces configured for channelized operation, you can insert channels (time slots) from one port (for example, channels carrying voice) directly into the other port on the PIM, replacing channels coming through the Routing Engine. This feature, known as drop-and-insert, allows you to integrate voice and data channels on a single T1 or E1 link.
The drop-and-insert feature allows you to remove the DS0 time slots of one T1 or E1 port and replace them by inserting the time slots of another T1 or E1 interface. This process saves you the cost of two lines.
Although you need not use the same time slots on both interfaces, the time slot count must be the same.
You must ensure that the signaling channels (port 16 for an E1 interface and port 24 for a T1 interface) are also part of the channels that are being switched through the drop-and-insert functionality. Junos does not support switching of voice and data between ports by default. The channels that are not configured for the drop-and-insert feature are used for normal traffic.
Both ports involved in the drop-and-insert configuration must use the same clock source—either the device's internal clock or an external clock. The following clock source settings are valid:
- When port 0 is set to use the internal clock, port 1 must also be set to use it.
- When port 0 is set to use its external clock, port 1 must be set to run on the same clock—the external clock for port 0.
- When port 1 is set to use its external clock, port 0 must be set to run on the same clock—the external clock for port 1.
