Specifications

MGX 8220 Service Modules 4-19
Circuit Emulation Service Module (8 port)
The CESM converts DS1/E1 or data streams into CBR AAL1 cells for transport across the ATM
network. The T1/E1 versions support a choice of structured or unstructured data transfer on a per
physical interface basis.
The CESM card supports loopback diagnostics features through the addchanloop and addlnloop
commands. Refer to the Cisco MGX 8220 Command Reference for details of these commands.
T1/E1 Structured Data Transfer
The T1/E1 structured data transfer mode supports:
• Synchronous timing only.
• nX64 Kbps Fractional DS1/E1 service with contiguous time slots. Any nX64 Kbps channel can
be mapped to any VC. Both SF and ESF framing modes are supported.
• For AAL1 interworking conversion only, CAS robbed bit for T1 (ABCD for ESF and SF frames)
and CAS for E1 (Channel 16).
• CCS channel transparently as data.
• Choice of partially filled cells.
• Idle Suppression/Detection for 1x64 CAS connections only.
T1/E1 Unstructured Data Transfer
The T1/E1 unstructured data transfer mode supports:
• Both synchronous and asynchronous clocking.
• T1 (1.544 Mbps) and E1 (2.048 Mbps) physical interfaces using either synchronous or
asynchronous timing. Asynchronous timing is supported using SRTS and adaptive clock
recovery.
• The special port type of “framingOnVcDisconnect”. This port type prevents a remote end CPE
from going to LOF by configuring a T1/E1 line in remote loopback mode when a connection
deletion/suspension is detected at the ATM interface.
• Ability to detect/display Yellow Alarm for T1 ESF framing.
An illustration of the 8 port CESM cards is provided in Figure4-10.