Electronic Design

OC-48/STS-16 Framer Manages Packet Protocols Over Sonet

The Internet Protocol is growing in wide-area networks (WANs). That doesn't mean that Sonet/ SDH systems are going away, though. These reliable, secure, and fast systems will continue to form the basis for most WANs. But triple-play services will require a new method for packaging all that data.

The XRT95L53 can handle the job. Developed by Exar Corp., this flexible Sonet/SDH framer and DS3/E3 mapper combines Generic Framing Procedure (GFP), virtual concatenation (VCAT), and the Link Capacity Adjustment Scheme (LACS) (see the figure). Vendors of multiservice access or provisioning platforms, Sonet/SDH add/drop and terminal multiplexers (ADM), layer 2 and 3 switches, and routers and storage-area network equipment can build flexible line cards to handle just about any packet format.

The chip integrates 48 clear-channel fractional DS3/E3 mappers, as well as VCAT and LCAS functions that allow the system to optimally map voice, video, and packet data over Sonet/SDH networks. An on-chip STS-1 (51-Mbit/s) cross-connect permits grooming at the STS-1 level to external devices enabling multiprotocol line cards required for next-generation ADMs. The XRT95L53 also incorporates flexible OC-48/OC-12/OC-3 SERDES, so the device can handle multiple applications concurrently at different data rates.

Also The XRT95L53 provides an optimal mix of legacy and next-generation features. That way, designers can build systems to support cutting-edge features like the General Framing Procedure (GFP) over DS3 and VCAT/LCAS without sacrificing the ability to do ATM over Sonet/SDH.

The chip supports packet mapping form Ethernet, PPP, Resilient Packet Ring (RPR), Multi-protocol Label Switching (MPLS), and any proprietary protocol a vendor may use. Using either the OIF SPI-3 interface or Exar's G-header interfaces, customers can map any type of data over Sonet/SDH on a per-channel basis.

Housed in a 780-pin BGA package, the XRT95L53 operates from 3.3- and 5-V supplies over the standard industrial temperature range. It costs $695 in 1000-unit quantities. Samples will be available within about 60 days.

Exar Corp.

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