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Cisco MGX 8850 Multiservice Switch Installation and Configuration
Release 1.1.31, Part Number 78-11223-03 Rev. B0, May 2005
Chapter 2 Module and Service Descriptions
Frame Relay Service Modules
CESM for T3 and E3 lines
The MGX-CESM-T3/E3 supports unstructured data transfer over a single T3 or E3 physical port at
speeds of 44.736 Mbps (T3) or 34.368 Mbps (E3). Only synchronous timing is supported.
MGX-CESM-T3/E3 is a two-card set consisting of a front card and either a T3 back card or an E3 back
card. Each back card provides two T3 or E3 ports (each port consists of two BNC connectors). Only port
one is available on the back card when used with the CESM-T3/E3 front card. 1:1 redundancy is
supported through a Y-cable on the line module back cards.
• Figure 2-26 on page 2-52 is an illustration of the MGX-CESM-T3/E3 front card.
• An illustration of the CESM back card for T3 lines is shown in Figure 2-27 on page 2-53.
• An illustration of the CESM back card for E3 lines is shown in Figure 2-28 on page 2-54.
CESM-T3/E3 Features
CESM cards support circuit emulation services using standards-based adaptation layers over ATM. The
CESM-T3E3 uses AAL1 for T3 or E3 unstructured transfer mode operation, per the ATM Forum’s
Circuit Emulation Specification, Version 2.0:
• Unstructured support: supports T3/E3 unstructured data transfer.
• Synchronous clocking: synchronous timing is the only mode that is supported. The clock must be
derived from the shelf.
• Onboard BERT: BERT support using on board BERT controller. BERT commands executed on
T3/E3 card.
• Maximum number of connections is one. In the unstructured mode, one logical port is used to
represent the T3/E3 line and one connection is added to the port to emulate the circuit.
• Programmable egress buffer size and CDV tolerance settings are supported for flexible support of
jitter and latency requirements.
• Bit count integrity is maintained when AAL1 lost-cell condition is detected.
• The CESM card provides ingress/egress data and signaling trunk conditioning per VC as per ATM
Forum CES V2.0.
• T3/E3 CESM cards can be Y-cabled to provide 1:1 hot standby redundancy of the CESM.
• CESM cards are supported by standards-based management tools, including SNMP, TFTP (for
configuration/statistics collection), and a command line interface. The Cisco WAN Manager and
CiscoView tools also provide full graphical user interface management support.
T3 Interfaces
T3 interfaces are supported as follows.
• One DSX-3 (44.736 Mbps +/-40 ppm) interfaces with dual female 75-ohm BNC coaxial connectors
per port (separate RX and TX)
• B3ZS line coding
• Pulse shape conforming to ANSI T1.102
• T3 bit error rate tester (BERT) and extended loop-up, loop-down pattern generation and verification
• 1:1 redundancy with Y-cabling for T3 CESM cards of the same type
• LOS alarm detection/generation support
• Transmitter loop-timed to receiver or synchronized to shelf