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Cisco MGX 8220 Installation and Configuration
Release 5.0, Part Number 78-6430-03 Rev. D0, November 2003
Chapter
Circuit Emulation Service Modules
Circuit Emulation Service Modules

Circuit Emulation Service Module (4-port)

The 4-port Circuit Emulation Service Module (CESM) is a two-card set consisting of a CESM front
card and a 4-port back card for T1 or E1 lines. The E1 line mo dule cards are further categorized by BNC
or DB15 connector type. The thre e p ossi b le lin e modules are
•LM-DB15-4T1
•LM-DB15-4E1
•LM-BNC-4E1
Up to 10 CESMs may be installed in a shelf in slots 5 through 14. A 1:N redundancy is supported
through the SRM-T1E1 board.
The main function of the CESM cards is to provide a constant bit rate (CBR) service for T1/E1 ports
over ATM BPX 8620 network.
The CESM converts DS1/E1 data s treams into CBR AAL1 cells for transport across the ATM network.
The CPE clock source should be configured in “loop” mode.
CESM card supports either 4 T1 or 4 E1 ports. Each T1 or E1 port supports a single synchronous
unstructured data stream with a data rate of 1.544 Mbps or T1 and 2.048 Mbps for E1. Data rates are
not configurable. A single CESM card supports up to four connections.
Timing for the two ends of a CBR connection (termination at the MGX 8220 shelf) must be the same
Stratum reference .
Performance monitoring of user applied structure (framing) is not supported.
The 4-port CESM card supports loopback di agnostics features t hrough the addchanloop and addlnloop
commands. Refer to the Cisco MGX 8220 Command Reference for details of these commands.
An illustration of the CESM card is provided in Figure4-14.