Service Resource Module; General Installation Requirements For The Mgx-Srm-3T3/B; Bulk Distribution And Redundancy Support - Cisco MGX 8850 Installation And Configuration Manual

Service Resource Module

This section describes how installing a Service Resource Module-3T3 (MGX-SRM-3T3/B) can
impact the installation of the service modules it supports. The MGX-SRM-3T3/B (or "SRM" for
brevity) can provide 1:N redundancy for the T1 and E1 cards and bulk distribution for T1 cards. It
has no communication with higher speed service modules, such as the MGX-FRSM-2CT3 and
MGX-FRSM-HS2/B. See Figure 4-43 for an illustration of the card set.
The multifunction SRM has the following capabilities:
•
A de-multiplexing function called bulk distribution carries traffic across the distribution bus
between the T3 lines on the MGX-SRM-3T3/B and the T1 service modules. Bulk distribution
can greatly reduce the number of T1 lines coming into the enclosure and the number of T1 back
cards.
•
1:N redundancy support for service modules with RJ-48 connectors.
•
Bit error rate testing (BERT) for T1 and subrate service module lines.

General Installation Requirements for the MGX-SRM-3T3/B

The following are card-level characteristics that apply to any SRM installation:
•
A non-redundant setup requires an MGX-SRM-3T3/B card set in slot 15 and a card set in slot 31.
The PXM in slot 7 controls the SRMs in slots 15 and 31.
•
An optional, redundant PXM in slot 8 controls the redundant SRMs in slots 16 and 32.
•
If the switch has a primary SRM pair for the primary PXM and the switch also has a redundant
PXM, it must have a redundant pair of SRMs.
•
An MGX-SRM-3T3 and the service modules it supports must reside in the same bay (upper or
lower half) of the card cage.
•
The distribution bus does not support slots 9, 10, 25, and 26, so any service module that uses bulk
distribution or relies on the distribution bus for redundancy cannot reside in these slots.

Bulk Distribution and Redundancy Support

The use of bulk distribution affects the requirements for SRM and service module back cards:
•
With bulk distribution and 1:N redundancy support by way of the distribution bus, the service
modules do not use back cards.
•
For just 1:N redundancy by way of the redundancy bus, the supported service modules must have
back cards—including one special redundancy back card. E1 redundancy requires the
R-RJ48-8E1 line module, and T1 redundancy requires the R-RJ48-8T1 line module.
For bulk distribution, the T3 lines connect to an external multiplexer. The T1 lines on the other side
of the multiplexer connect to the CPE. The SRM converts the received traffic from its T3 lines to T1
channels and sends the data to linked service modules. For instructions on linking T1 channels and
card slots to the MGX-SRM-3T3/B, see Chapter 6, "Card and Service Configuration."
For bulk distribution of T1 lines, note the following about the MGX-SRM-3T3/B:
•
Each T3 line can support up to 28 T1 channels.
•
The maximum number of T1 channels the it can support at one time is 80.
Service Resource Module
Enclosure and Card Installation 4-49