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Configuring a Channelized T1/E1 Interface to Drop and Insert Time Slots

 

On channelized T1/E1 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, to replace channels coming through the Routing Engine. This feature, known as drop and insert, allows you to integrate voice and data on a single T1 or E1 link by removing the DS0 time slots of one T1 or E1 port and replacing them by inserting the time slots of another T1 or E1 port. It is not necessary to use the same time slots on both interfaces, but the time slots count must be same. The channels that are not configured for the drop-and-insert feature are used for normal traffic.

You can configure:

  • 30 channelized E1 time slots, with the 16th time slot operating as the signaling channel

  • 23 channelized T1 time slots, with the 24th time slot operating as the signaling channel

The signaling channel, or D-channel, must be part of the channels that are being switched through the drop-and-insert functionality. The Junos OS does not support switching of voice and data between ports by default.

Both ports involved in the drop-and-insert configuration must use the same clock source—either the router'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, and vice versa.

  • 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.

For more details about valid clock combinations, see the Junos OS Interfaces and Routing Configuration Guide.

To configure drop-and-insert time slots on a channelized T1 interface, include the partition statement at the [edit interfaces ct1-pim/0/port] hierarchy level with the timeslots statement and interface-type statements specified:

This configuration creates interfaces ds-pim/0/port:1, ds-pim/0/port:2, and ds-pim/0/port:3.

Use the same configuration to create drop-and insert time slots on a channelized E1 interface by including the partition statement and options at the [edit interfaces ce1-pim/0/port] hierarchy level.