NMC-RX 7.2.x User Guide, Vol. 1 > Configuring the System > Line Module Redundancy Groups

Line Module Redundancy Groups

The NMC-RX software can recognize line module redundancy groups on a device and display which module is active and inactive (spared for). A redundancy group folder is created in the Instance Explorer, and the line modules in that group are placed in the folder.

Table 18 contains some common redundancy group terms.

 Table 18:  Line Module Redundancy Group Terms 

 Term
 Description

 Redundancy group

 Group of line modules that contain a spare and one or more primary line modules in adjacent slots. To have a redundancy group, you must install a special midplane that allows the spare line module to take over (or spare) for any of the primary line modules. Redundancy groups come in several sizes from 2 to 6 line modules. For example:

  
 2-module group is referred to as 1+1 (1 primary + 1 spare) redundancy
  
 3-module group is referred to as 2+1 (2 primary + 1 spare) redundancy
  
 6-module group is referred to as 5+1 (5 primary + 1 spare) redundancy



 Spare line module


  
 Line module in the lowest-numbered slot of the redundancy group. The spare takes over when a primary line module goes offline.
  
 Not configurable (except for admin status)



 Primary line module


  
 Active line module that is not a spare
  
 When offline, primary line modules are spared for by the spare line module in the group
  
 Configurable when online and when being spared for by a spare line module
  
 If there are multiple offline primary line modules, only one can be spared for by a spare line module



 Sparing for


  
 Spare line module takes over for a primary line module
  
 When the primary line module is offline, the state of the spare line module changes from standby to online. This process is also called switchover or failover.




 

Example 1

In this example, slot 5 has a spare line module in standby mode, and slot 6 has a primary line module that is online in a 1+1 redundancy group. Note that the group is issued an ID (5).

Example 2

In this example, slots 5 through 7 are in a 2+1 redundancy group. The spare line module in slot 5 is currently sparing for the primary line module in slot 6, which is inactive. The primary line module in slot 7 is also inactive, but because the spare line module is already sparing for slot 6, slot 7 is colored red and labeled Offline.