Nortel Networks BCM1000 manual Explaining Double Density, DS30 bus model

62Chapter 4 Selecting the media bay modules for your system

Figure 25 DS30 bus model

DS256 on MSC

DS30 blocks available to modules in a 2/6 split

DS30 bus 02

DS30 bus 03

DS30 bus 04

DS30 bus 05

DS30 bus 06

DS30 bus 07

Four offsets per bus

DS30 blocks

available to modules in a 3/5 split

DS30 bus numbers are set using the number 4, 5, and 6 DIP switches on the back or underside of the media bay modules. The exception is the FEM module. The FEM DIP switches turn on ports, each of which consumes one DS30 bus.

Explaining Double Density

BCM 3.0 software introduced the concept of single and double density for DS30 buses supporting station modules. On these buses the B2 bus blocks are reconfigured as B1 bus blocks, thereby, doubling telephone capacity. However, only DSM16+, DSM32+ and ASM/ASM8+ modules can support the second set of DNs. The DSM16+ and DSM32+ modules can be configured for either single density, which access only the top 16 DNs, or double density, which accesses all 32 DNs.

Default BCM 3.0 and newer systems are configured as Partial Double Density (PDD) systems, in that they maintain DS30 06 and 07 in the original configuration of 16 DNs per bus. This accommodates those systems which use Companion. The system can be set to Full Double Density (FDD) at system startup or once the system is setup. When the system is set to FDD, DS30 06 and 07 allow access to the second set of DNs, and they are no longer available for Companion operation.

Note: Devices that share a DS30 bus must be identical. Use two DSM 16+ modules set to double density on a single DS30 bus.

A DSM 32+ set to double density requires a full DS30 bus.

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