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Mapper supports all protocols

Posted: 26 Oct 2005 ?? ?Print Version ?Bookmark and Share

Keywords:exar? mapper/framer? infineon technologies? ethernet-over-sonet? eos?

Exar is expecting their new mapper/framer, which is actually part Infineon Technologies AG, to jumpstart its entry into the Ethernet-over-Sonet (EoS) market.

In April, Exar purchased a significant chunk of Infineon's Optical Networking (ON) business. The acquisition gave Exar additional know-how and a system engineering team that launched the company into the EoS market, said Sid Yenamandra, Exar's senior manger, Ethernet and Sonet/SDH product line.

The first device in this upcoming family of mappers (EXtendAR 48) is aimed at the packet portion of the ON arena. There are no other EoS framer packets that permit any type of packet data to be mapped and transmitted over legacy systems, according to Yenamandra. "No one else is integrating 48 channels of DS3/E3 mapping on a single chip with virtual VCAT/LCAS and legacy framing functionality," he said. In the past, this function required two framers.

The legacy market is all related to the Sonet protocol, without any Ethernet. Consequently, there are plenty of framers available for Sonet. Now, however, there is demand to map Ethernet over the legacy infrastructure to deliver triple-play applications (voice, video and data), and EXtendAR 48 enables mapping of packet Data over Sonet, Yenamandra said.

Highly integrated devices are blossoming in the networking arena. Essentially, Exar's mapper is a system-on-chip (SoC) that is taking customers to the next level for triple-play applications. This mapper is universal because even though it will mostly be used in Sonet infrastructures, the device can be mapped to any type of Ethernet.

In order to incorporate next generation protocol features, companies have had to remove some of the old functions to add new oneswhen using the same package. Exar, however, built its architecture from scratch, and then developed protocol engines that are said to be unique in the way they incorporate all of the old and new protocol features. "We've compacted the legacy functions into highly integrated engines so we could fit both the old and new functions in the same package," Yenamandra said.

Exar's XRT94L55, for instance, which is about a year old, is a legacy framer in a 780 PBGA, which measures 37.5-by-37.5mm. The new device, meanwhile, utilizes the same package size, but incorporates legacy features, as well as Ethernet features.

One of the key features of the new mapper is that it supports flexible mapping Ethernet and can map other traffic over Sonet too. To do this, Exar implemented a special protocol, called the G-header interface, which enables it to map any type of proprietary data into Sonet. It is a protocol that was developed using SPI-3 as the electrical interconnect. It has future proofed the EXtendAR 48M device, Yenamandra said. "Every day new protocols or another packet data comes out that needs to be mapped over Sonet. We built in a level of flexibility so if there are changes, you can input the new information using our G-header protocol," he explained.

In terms of integration, the STS-1 cross connect, which is typically an external function, is now on-chip. "We can hold 2.5 Gigabits/s worth of traffic in this device so you can groom the data down to the STS-1 level," Yenamandra said. This enables the device to add/drop data at STS-1 levels, and thereby provides superior functional performance at lower granularities.

The functional block diagram below shows three different ways to use the mapper in EoS system applications. The first one is the most cost effective for designers. The second diagram gets more into Ethernet switching and the third one is for full, triple-play services.

- Bettyann Liotta


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