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Chapter 6
Card and Service Configuration
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Redundancy Support by the MGX-SRM-3T3/C
The MGX-SRM-3T3/C can provide redundancy to service modules with T1 or E1 lines. For E1 or T1
modules, it can provide redundancy through the redundancy bus. For T1 modules only, it can provide
redundancy through the distribution bus. The redundancy and distribution buses impose different
requirements, but the common requirement is that all primary and secondary cards supported by a
particular MGX-SRM-3T3/C must reside on the same level of the card cage as that SRM.
The need for back cards and the choice of bus for redundancy support depends on whether the
MGX-SRM-3T3/C must provide bulk distribution:
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With redundancy provided by the SRM, no Y-cables are necessary because the MGX-SRM-3T3/C itself
passes the traffic to the redundant front card if a failure necessitates switchover. Conversely, any card
with 1:1 redundancy supported by Y-cabling does not require an SRM. For example, the FRSM-VHS
cards have 1:1 redundancy through a Y-cable. The MGX-SRM-3T3/C redundancy feature is particularly
important for cards that do not have Y-cable redundancy—the T1 and E1 service modules.
Configuring Redundancy Through the Redundancy Bus
For redundancy that utilizes the redundancy bus, the characteristics are:
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To configure redundancy through the redundancy bus:
Step 1
Execute addred on the active PXM1:
addred <redPrimarySlotNum> <redSecondarySlotNum> <RedType>
where:
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Release 1.1.31, Part Number 78-11215-03 Rev. B0, May 2001
TargetSlotNum
T1 service module slot number to be linked to the T1 line, in
the ranges: 3–6 and 10–13.
TargetSlotLineNum T1 line number in the slot to be linked, in the range 1–8.
With bulk distribution, the T1 service modules do not use back cards. The MGX-SRM-3T3/C uses
the distribution bus to support redundancy.
Without bulk distribution, the supported service modules must have back cards. The redundant card
set requires a special redundancy back card (the R-RJ48-8T1 or R-RJ48-8E). The primary card sets
use standard back cards (RJ48-8T1 or RJ48-8E1).
Both the primary and the redundant front cards must have back cards. The secondary back card must
be the version specifically designed to be redundant cards. Examples are the R-RJ48-8T1 and
R-RJ48-8E1, where the first "R" means redundant.
An MGX-SRM-3T3/C can redirect traffic for only one failed card at a time regardless of the number
of redundant groups you have configured to rely on that MGX-SRM-3T3/C for redundancy.
redPrimarySlotNum Slot number that contains the primary card of the card
pair, in the ranges 4–6 or 11–13.
Cisco MGX 8230 Edge Concentrator Installation and Configuration
Service Resource Module
6-51
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