Specifications

MGX 8220 Service Modules 4-31
Service Module Back Cards
Details of the CLI and individual commands are found in the Cisco MGX 8220 Command Reference
publication.
Service Module Back Cards
The available MGX 8220 back cards are as follows.
T1/T3 Backcards
The MGX 8220 shelf provides back cards for service modules that connect to 4 T1, 4 E1, 8 T1, and
8 E1 lines. Depending upon the number of ports and the type of line (T1 or E1) DB-15, BNC, RJ48,
and SMB connectors are used. The possible back cards (see Figure4-16) are:
• DB15-4T1-BC
• DB15-4E1-BC
• BNC-4E1-BC
• RJ48-T1-BC
• RJ48-E1-BC
• SMB-E1-BC
The back cards provide the physical line connections to either the T1 or E1 lines and communicate
with their front cards through the MGX 8220 backplane. A front card/back card set are always
installed in the same slot position.
X.21 Backcards
The FRSM-HS1 uses a backcard which supports 4 X.21 ports using DB-15 connectors.
DB15-4X.21-BC
The X.21 Physical interface specifies a DB-15 female connector (DCE type according to ISO 4903).
Pin functions can be controlled in software to change from DCE to DTE.
HSSI Backcards
The HSSI (High Speed Serial Interface) backcard supports two HSSI ports using a female SCSI-II
connectors.
DTE to DCE control is achieved through a combination software controls, and a "NULL MODEM"
connector.
Redundancy Backcards
When the SRM is used to provide 1:N redundancy for T1/E1 service modules, the standby
(redundant) card set uses a special redundancy backcard. Following are three types of redundancy
backcards: R-DB15-4T1, R-DB15-4E1, and R-BNC-4E1. The one you use depends upon the line
type (T1 or E1) and the E1 connector type (DB-15 or BNC) of your service module. (See Figure4-16
and Figure4-17.) When 1:N redundancy is invoked, the physical lines to the failed service module
backcard are still used. However, the signals are still routed to and from the redundant backcard.