Nortel Networks 400 4.0, BCM200 manual Assigning DS30 resources

114Chapter 8 Installing a media bay module (MBM)

Assigning DS30 resources

MBMs are assigned to DS30 buses in a specific hierarchical manner. This section describes the preferred order of positioning for each type of MBM.

The following are some general notes about assigning MBMs:

•The DIP switches on the DDIM are used to set the DS30 designation for the DTM part of the MBM. The MBM automatically assigns an additional DS30 for the data part of the DDIM. You cannot choose DS30 7 for the DDIM because the data MBM would not be accessible. The same applies to DS30 6 if your system is set to a 3/5 split. Refer to “DDIM switch settings” on page 122.

•If you chose a 3/5 bus split for your system, DS30 7 cannot be used by any MBM. For MBMs that require two buses, this means that you cannot set the DIP switches to DS30 6 for those MBMs because the second level of lines falls into DS30 7, which is not accessible (see Figure 68 on page 115).

•Refer to “Understanding DS30 numbers” on page 109 for more information about 2/6 and 3/5 DS30 bus splits.

•DSM32 MBMs require two DS30 numbers. When you assign the first DS30 number to a DSM32, the MBM automatically adds the next DS30 number. For example, if you assign DS30 2 to a DSM32, it uses DS30 2 and 03. However, you cannot choose DS30 7 for the DSM32 because the second level of DSM lines would not be accessible. The same applies to DS30 6 if your system is set to a 3/5 split. Refer to “DSM switch settings” on page 130.

•DSM 32+ MBMs can be set to either single or double density. When they are set to double density, the MBM only requires one DS30 bus.

•The DIP switches on the 4x16 are used to set the DS30 designation and offset for the CTM part of the MBM. The MBM automatically assigns the first half of the next bus for the 16 DSM lines. However, you cannot choose DS30 7 for the 4x16 because the DSM lines would not be accessible. The same applies to DS30 6 if your system is set to a 3/5 split. Refer to “4x16 switch settings” on page 126.

•The CTM8 uses two offsets on a DS30 bus. You assign the first offset to the MBM, and the second offset is automatically selected. This means that you can choose offset pairs 0-1, 1-2, or 2-3. Because the MBM requires two offsets on the same DS30, you cannot select offset 3. Refer to “CTM switch settings” on page 123.

•Not all MBMs are available to all systems. Refer to “Selecting MBMs for your BCM system” on page 105 for specifics about each MBM.

Note: Remember, if you have chosen a 3/5 bus split for your system, DS30 bus 7 is no longer available for MBMs.

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