Electronic Design

Add/Drop Multiplexer-On-A-Chip Targets Metro Optical Networks

The fastest-growing segments of the telecommunications market in the coming years will involve the access and metro edge, according to PMC-Sierra, where carriers want to offer value-added services to enterprises like Ethernet Virtual LANs. These sectors use Sonet interconnectivity, a highly effective but expensive transport method.

One of the key components in any Sonet ring is the add/drop multiplexer (ADM). PMC-Sierra reduced this complex rack-sized piece of equipment into two different single-chip solutions that can be packaged into the smaller "pizza box" form factor. The PM5337 ADM 622 and PM5338 ADM 622 PDH (plesiochronous digital hierarchy) chips give designers an efficient way to build robust, small-footprint carrier-class equipment, leading to faster time-to-market. The ADM 622 devices are optimized for OC-3/STM-1 and OC-12/STM-4 155 and 622-Mbit/s Sonet service.

The company integrated seven of its earlier chips into one package to form the complete ADM, less the optical transceivers. These chips incorporate Sonet/SDH framers and pointer processors, PDH mappers, expansion interfaces, and a cross connect. The ADM 622 also includes Ethernet-over-Sonet/SDH interfaces with layer 2 processing.

With these features, designers can easily add all of the characteristics that carriers look for—reliable transport of various client services via the carrier's existing infrastructure and flexible support for current and next-generation services—all with scalability. The devices include the standard Scalable Bandwidth Interconnect Transport (SBI-TR) bus, which connects directly to the company's PM4329 HDLIU 32 device and PDH client interfaces.

The ADM 622 devices have three DS3/E3, three EC-1, 28 T1, and 21 E1 standard telecom interfaces. The PM5337 also has eight 10/100 Ethernet ports and one Gigabit Ethernet port. Most common mapping services are fully supported. The layer 2 processor in the ADM 622 provides aggregation, grooming, and policing. It also provides Ethernet operations, administration, and maintenance (OAM) capabilities to enable next-generation services without needing an external Ethernet switch or network processor. Using this chip, carriers may provide service granularity in 1-Mbit/s increments rather than the usual 1.5-, 2-, or 51.84-Mbit/s increments usually associated with virtual concatenation.

The PM5337 and PM5338 are made with 0.13-µm CMOS and are housed in an 896-ball, 31- by 31-mm flip-chip ball-grid-array (BGA) package. Price and availability information must be obtained from the company directly.

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