PM73121ꢀAAL1gator II
Data Sheet
PMC-Sierra, Inc.
PMC-980620
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AAL1 SAR Processor
1 SYSTEM APPLICATIONS
An essential function for ATM switches is to emulate existing Time Division Multiplexing
(TDM) circuits. Since most voice and data services are currently provided by TDM circuits,
seamless interworking between TDM and ATM has become a system requirement. The ATM
Forum has standardized an internetworking function that satisfies this requirement in the Circuit
Emulation Service (CES) Specification. The AAL1gator II is a direct implementation of that ser-
vice specification in silicon, including the complex N × 64 channelized service and support of
CAS.
1.1 Replacing a TDM Digital Access Cross-connect System (DACS) with an ATM System
In one public network application, a TDM DACS is replaced with an ATM system containing an
AAL1gator II. When the backbone trunk of a network is changed from TDM to ATM, the TDM
DACSs will probably be converted from TDM to ATM. The existing leased line services pro-
vided by the DACSs must then be provisioned with the ATM DACS. In this manner, TDM, frame
relay, and ATM circuits can be provided in a single network, as shown in Figure 4.
T1 Service
Fractional T1 Service
TDM Backbone
TDM DACS
Digital Data Service
T1 Service
Circuit Emulation
Card
Fractional T1 Service
ATM Backbone
ATM DACS
AAL1gator II
(PM73121)
DDS Service
Figure 4. Using the AAL1gator II as Part of a TDM DACS Replacement
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PMC [ PMC-SIERRA, INC ]
