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ATM Switch Router Software Configuration Guide
OL-7396-01
Chapter19 Configuring Circuit Emulation Services
Configuring T1/E1 Unstructured Circuit Emulation Services
Configuring Network Clocking for Unstructured CES
Circuit emulation services require that the network clock be configured properly. Unstructured services
can use synchronous, Synchronous Residual Time Stamp (SRTS), or adaptive clocking mode. For
instructions on configuring network clocking, see Chapter 3, “Initially Configuring the
ATM Switch Router.” For a discussion of clocking issues and network examples, refer to the network
clock synchronization and network clocking for CES topics in the Guide to ATM Technology.
Configuring Synchronous Clocking With an OC-12c Interface Module
When synchronous clocking is being used and propagated via an OC-12c interface module, be sure to
use the following configurations:
• For the Catalyst 8540 MSR, use the optional clocking module.
• For the Catalyst 8510 MSR and LightStream 1010 ATM switch routers, use feature card per flow
queueing (FC-PFQ).
Configuring a Hard PVC for Unstructured CES
A CES module converts CBR traffic into ATM cells for propagation through an ATM network. CBR
traffic arriving on a CES module port must first be segmented into ATM cells. This cell stream is then
directed to an outgoing ATM or CBR port.
Note As a general rule when configuring a hard PVC, you must interconnect a CBR port and an ATM port in
the same ATM switch router chassis.
Figure 19-1 displays unstructured circuit emulation services configured on an ATM switch router, using
ATM and CES interface modules to create a hard PVC. In this example, the hard permanent virtual
channel (PVC) also uses adaptive clocking, and this CES circuit enables bidirectional, unstructured CBR
traffic to flow between these two modules.
Figure 19-1 Hard PVC Configured for Unstructured CES
CES port adapterATM port adapter
Target switch
27213
Destination port
Port ID - ATM0/1/3
(Explicit VPI 0, VCI 100)
Source port
Port ID - CBR3/0/0
(implicit VPI 0, VCI 16)
00 123123
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