Electronic Design

Ethernet-Over-Sonet/SDH Mapper Offers Carrier-Class Features

Ethernet dominates the local-area network (LAN) space. However, carriers continue to use legacy plesiochronous digital hierarchy (PDH) T1/T3 formats. Also, Sonet and synchronous digital hierarchy (SDH) still dominate the metro-area network (MAN) and widearea network (WAN) arenas. Making the LAN and MAN worlds compatible requires the ability to put Ethernet packets efficiently into the synchronous optical system formats of Sonet and SDH.

PMC-Sierra's next-generation PM4390 Arrow M8xFE mapper chip addresses the needs of metro and last-mile Ethernet access, Internet Protocol (IP) digital-subscriber-line access multiplexers (DSLAMs), and 3G wireless backhaul. Applications include access and metro Ethernet adddropmultiplexers, multiservice provisioningplatforms, terminal multiplexers, and next-generation Ethernet switches.

The PM4390 Arrow M8xFE offers PDHlike performance monitoring for last-mile Ethernet access. The integrated support for Ethernet operation, administration, and maintenance (OAM)—as defined by the 802.3ah Ethernet in the First Mile (EFM) standard—provides link monitoring and fault signaling. This enables remote performance monitoring comparable to legacy T1/E1 services, minimizing truck rolls since the carrier can perform provisioning and some troubleshooting and maintenance.

With the chip's integrated rate limiting and policing capabilities, carriers can offer enterprise customers flexible service models like Ethernet Private Line and Ethernet Virtual Private Line services. The integrated packet manipulation supports standardsbased very large-scale neighborhood or multiprotocol label switching (MPLS) encapsulation, enabling internetworking-with next-generation IP/MPLS converged metro core networks.

The chip addresses the growing number of Ethernet ports in last-mile access in DSLAMs and 3G wireless basestation uplinks. These high-volume, cost-sensitive access backhaul applications were the main drivers for integrating packet multiplexing and OAM capabilities. By eliminating the need for an external packet processing element, it's one of the most cost-effective data-mapping solutions available.

The PM4390 Arrow M8xFE can be built into an Ethernet line card of various configurations, including private line, aggregation, or grooming (see the figure). It handles up to eight Ethernet 10/100 ports or one Gigabit Ethernet (GE) port. The interface is the standard Serial Media Independent Interface (SMII) or Gigabit Media Independent Interface (GMII) between the external Ethernet physical-layer chips and the internal media-access controllers.

The chip handles the Ethernet packet encapsulation via the Generic Framing Procedure and virtual concatenation into Ethernet over Sonet/SDH format. It also integrates grooming, aggregation, and Ethernet OAM functions. The output can be configured as a single 622.08- or 2488.32-Mbit/s serial Sonet/SDH interface or a multidrop 8 77.76-MHz parallel TelecomBus Interface. These interfaces are compatible with low-voltage differential signaling (LVDS).

The package is a 31- by 31-mm 896-ball flip-chip ball-grid array. The core runs at 1.2 V with 2.5 V and/or 3.3 V for I/O.

Contact PMC-Sierra for pricing.

PMC-Sierra Inc.

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