Technical Documentation

Configuring the JUNOS Software to Support Channelized DS3-to-DS0 Naming for Channel Groups and Time Slots

You can configure 28 T1 channels per T3 interface. Each T1 link can have up to eight channel groups, and each channel group can hold any combination of DS0 time slots. To specify the T1 link and DS0 channel group number in the name, use colons (:) as separators. For example, a Channelized DS3-to-DS0 PIC might have the following physical and virtual interfaces:


where x is a T1 link ranging from 0 through 27 and y is a DS0 channel group ranging from 0 through 7. (See Ranges for Channelized DS3-to-DS0 Configuration for more information about ranges.)

You can use any of the values within the range available for x and y; you do not have to configure the links sequentially. The software applies the interface options you configure according to the following rules:

  • You can configure t3-options for t1 link 0 and channel group 0 only; for example, ds-/0/0/0:0:0.
  • You can configure t1-options for any t1 link value, but only for channel group 0; for example, ds-0/0/0:x:0.
  • There are no restrictions on changing the default ds0-options.
  • If you delete a configuration you previously committed for channel group 0, the options return to the default values.

To configure the channel groups and time slots for a channelized DS3 interface, include the channel-group and timeslots statements at the [edit chassis fpc slot-number pic pic-number ct3 port port-number t1 link-number] hierarchy level:

[edit chassis fpc slot-number pic pic-number ct3 port port-number t1 link-number]channel-group channel-number timeslots slot-number;

Note: If you commit the interface name but do not include the [edit chassis] configuration, the Channelized DS3-to-DS0 PIC behaves like a Channelized DS3-to- DS1 PIC: none of the DS0 functionality is accessible.

Note: The FPC slot range depends on the platform. The maximum range of 0 through 7 applies to M40 routers; for M20 routers, the range is 0 through 3; for M10 routers the range is 0 through 1; for M5 routers, the only applicable value is 0. The Multichannel DS3 (Channelized DS3-to-DS0) PIC is not supported on M160 routers.

Bandwidth limitations restrict the interface to a maximum of 128 channel groups per T3 port, rather than the theoretical maximum of 8 x 28 = 224.

There are 24 time slots on a T1 interface. You can designate any combination of time slots for usage, but you can use each time slot number on only one channel group within the same T1 link.

To use time slots 1 through 10, designate slot-number as in this example:

[edit chassis fpc 0 pic 1 ct3 port 5 t1 22]channel-group 7 timeslots 1-10;

To use time slots 1 through 5, time slot 10, and time slot 24, designate slot-number as in this example:

[edit chassis fpc 2 pic pic-number1 ct3 port 0 t1 8]channel-group 4 timeslots 1-5,10,24;

Do not include spaces in the list of time slot numbers.

Published: 2010-04-26