Nortel Networks 400 4.0 User Manual

Chapter 8 Installing a media bay module (MBM)

BCM200/400 4.0 Installation and Maintenance Guide

Offsets are assigned using DIP switches 1, 2, and 3 on the MBM. 

 shows a DS30 broken down into four offset groups of four (single density) 

or eight (double density) lines each. 

Figure 65   Offsets are part of DS30 channel line groups

 shows the DS30 bus requirements of each MBM. Note the differences between MBMs 

set to single density and MBMs set to double density.

Note: MBMs that do not, or cannot, share DS30 buses always assign the offset as 0 
(zero). As well, if the MBM requires more than one bus, such as the 4x16 or the DDIM, 
only the first DS30 is set on the DIP switches. The next consecutive DS30 bus is 
automatically assigned by the MBM.

Note: When you enable a station MBM for double density, the line numbers double.

Note: If you choose a CTM8, DDIM, or 4x16, there are some restrictions on the offsets 
you can choose. Refer to the DIP switch settings in 

and 

Offsets have 

4 lines (single-density) 

8 lines (double-density)

1 DS30 bus

16 lines/32 time slots (single-density) 

32 lines/32 time slots (double-density)