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PORT TYPES/INSTALLATION COMPATIBILITIES
6-13
channel signaling bits must be passed directly between two DS1/DMI ports without any switch
processing software interaction. Any DS1/DMI port, regardless of its operating mode, may be
switched into its corresponding transparent mode through administration. Additional details about
DS1/DMI port types can be found in the DSC feature reference.
SYSTEM 85 DS1 OR DMI-MOS, TRADITIONAL MODULES (ANN35)
The operating mode and supported port types for System 85 DS1 of DMI-MOS (ANN35) in
traditional modules are described next.
Operating Mode
DMI-MOS only works in trunk mode and it does not support line mode capabilities. The backplane
strap, which may optionally be used for DMI-BOS, must not be configured. Here, DMI-MOS
provides the functional equivalent of six analog circuit packs, each providing four ports, but using
message-oriented-signaling. Therefore, the DMI-MOS requires six slots: one for the actual circuit
pack and five as virtual slots. Each virtual slot provides four ports.
System 85 hardware allows a maximum of four trunk circuits per slot. Therefore, this mode only
uses four backplane time-slots from each of six carrier slots (24 time-slots producing 24 DMI-MOS
channels).
A maximum of two DMI-MOS trunk-mode circuit packs may be configured in each DS1 or MFAT
carrier. They may only be placed in slots 5 and 18. Virtual slots are the leftmost three slots of the
left quarter and the two slots immediately to the right of the real DMI-MOS in the right quarter of
the half carrier in which the interface is contained.
CAUTION: These virtual slots must be left vacant or damage to a port board and the DMI
could result.
With R2V4 and later versions, a DS1 or MFAT carrier may be configured with both DMI-MOS and
DMI-BOS circuit packs. Recall that the DMI-BOS circuit pack may be used to provide either
line+trunk mode or line-only mode. When the two are mixed within the same carrier, the
appropriate restrictions apply to each; refer to Operating Modes under the heading Generic 2
DS1/DMI-BOS.
A carrier equipped with two trunk mode DMI-MOSs will have four slots available for other port
boards in physical slots 3, 8, 16, and 21. Figure 6-2, Physical and Virtual Carrier Slot Relationships,
Line+Trunk Mode, shows the carrier slots, physical versus virtual slot locations, and their relationship
to trunk mode and/or line+trunk Mode use.