Specifications

4-16 Cisco MGX 8220 Reference, Release 4.1

Circuit Emulation Service Module (4 port)

The 4 port Circuit Emulation Service Module (CESM) is a two-card set consisting of an CESM

function module front card and either a 4 T1, 4 E1 line module back card. The E1 line module cards

are further categorized by BNC or DB15 connector type. The three possible line 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. 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 streams 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.

An illustration of the CESM card is provided in Figure4-9.