Mike's PBX Cookbook

51,61,81 Block Diagrams

Meridian large system components and logical connections:

Option 51C

The Option 51C has a single Core/Network module, supporting a Half Network Group (16 Loops, 0-15). The core is not redundant. PRI/T1 cards go in the Network section of the Core/Net module.

Intelligent Peripheral Equipment (IPE) modules contain the station and analog trunk cards (anything with a TN). IPE Modules are standard.

Full size: Option 51C

Option 51C Block Diagram

Option 61C

The Option 61C adds a second Core/Network module for core redundancy, and expands the system to 1 Full Network Group (32 Loops, 0-31). The two cores are connected via an "interprocessor bus". As with the 51C, PRI/T1 cards occupy a loop slot in the Network section of the Core/Net module.

Shelf 0 and 1 Control Bus's are connected via J3 and J4 from the 3 Port-Extender cards (3PE), and not via A,B,C cables as with the Option 81C.

Full size: Option 61C

Option 61C Block Diagram

Option 81C

The Option 81C, with IGS, supports up to 5 Network Groups 0-4 (160 Loops, 0-159). The diagram shows two Network Groups: 0 and 1. ABC cables are used to connect the Control Buses in each group.

From Release 25, a dual-ring Fiber Network may replace the older IGS (intergroup switching) cards and module, expanding an Option 81/81C from 5 to 8 network groups, or from 160 to 256 loops. A NTRB33 FIJI card is installed in each Core/Net or Network module (not shown).

Full size: Option 81C

Option 81C Block Diagram

Click image to view, or right-click and select "Open Link in New Window/Tab". Alternatively, open the PDF version.

On the Buses

Not those buses, the 'system' buses:

Network BusVoice and data time slots. For example, path for phone conversations, tones, and music on hold.
Signal BusSignaling state changes (eg. off-hook or dialing from IPE equipment) to Peripheral Signal cards.
Control Bus
(24 bit)
Direct link from any network card to the Three-Port Extender (3PE) card in the same network group.
Used by the Peripheral Signal card to alert the Call Processor (CP) of changes in the signaling state.
(32 bit)
Link between the active Call Processor (CP) and the other core components, eg. hard/floppy drive, etc.
Instructions to and from the active CP, pass through a CNI card in the Core, to a Network 3PE card.
IPE BusOn the backplane of each IPE module, the link from the IPE cards to their Controller card.
From the Controller card, timeslots are sent to or from a Superloop card.
Source: Nortel Training Material
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