Merlot Adds Quality of Service to Ethernet
Merlot Communications is bringing new Ethernet technology to ComNet that promises to make Ethernet deterministic with an ATM-like quality of service. Besides ASIC-based technology that it hopes will capture the interest of major Ethernet vendors, Merlot gave showgoers a glimpse of an integrated access device the company will introduce later this year. It turns out that IADs were a hot property at ComNet.
By: John Spofford
Merlot Communications Inc. is offering a way to integrate voice and data over high-speed local-area networks (LANs) that it claims is both simple and cost-efficient.
The network equipment vendor has developed a standards-based technology that gives the Ethernet protocol many of the Quality of Service (QoS) characteristics of asynchronous transfer mode (ATM), a protocol designed to transport simultaneously voice, video, and computer data information.
Merlot is packaging its technology in an application specific integrated circuit (ASIC) licensable by original equipment manufacturers. The company demonstrated the technology at the ComNet/DC tradeshow, hoping to interest Ethernet equipment manufacturers in the new technology. At its booth, Merlot ran a single voice line simultaneously with a digital video clip over a 10 Mbps switched Ethernet connection.
"Everyone is trying to pass delay sensitive traffic over data networks using voice compression, increased speeds while adding drivers or protocols," said Merlot president and CEO, Michael Centrella. "We looked at the problem and decide to take an approach that is much more practical."
Making an "Ethernet SAR"
The Merlot PDQ-Chip implements an Ethernet segmentation and reassembly (SAR) capability that conditions Ethernet networks so that delay sensitive traffic such as voice and video receive constant bit rate (CBR) priority over the less time-sensitive data. Each user on the LAN gets a separate real-time connection for voice and data.
The CBR traffic is directly mappable to the CBR ATM traffic type, according to Merlot. In this way, the technology could essentially extend the QoS of an ATM backbone into the LAN.
"In addition to any potential OEM deals, we also are developing an integrated access device (IAD) based upon the Merlot PDQ-Chip," Centrella.
Intended for small- to medium-sized businesses, Merlot's device will sit on the edge of the network either on the customer's premise or at a network service provider access point. The product will include multiple high-speed WAN interfaces including T-1, analog phone, ISDN, xDSL, or cable modem.
Hot Topic at ComNet
IADs offer a carrier or network service provider a way to offer small office/home office (SOHO) customers an all-in-one data networking and voice service. This market niche is heating up.
For example, AG Communication Systems and Paradyne Corp. unveiled the SuperLine Integrated Access System at ComNet. The SuperLine system consists of two components: the Superline Integrated Access Platform (IAP) manufactured by AG Communication and the SuperLine Integrated Access Device (IAD) made by Paradyne.
Using Paradyne's digital subscriber line (DSL) technology, SuperLine uses quadrature amplitude modulation to provide three independent phone lines on a single copper twisted pair. In addition, it reserves a 500 Kbps data channel on the same line. All three analog lines are compatible with the digital pulse code modulation methods used in the V.90 56 Kbps modem standard.
The SuperLine IAP resides in a service provider's central office or beside a remote digital loop carrier (DLC). The SuperLine IAD—a piece of equipment similar in size to a modem—is located in a customer's home or office. Superline will allow service providers to deliver a bundle of communications services to SOHO and residential customers that includes up to two additional phone lines and Ethernet data over the same copper wire used today for existing phone service.
Pairgain adds HDSL2 to Avidia
PairGain Technologies announced an upgraded Avidia System integrated access concentrator that supports HDSL2—an improved version of high-bit rate DSL (HDSL). Carriers have used HDSL for a number of years to deliver T-1 services over two pair of voice-grade copper. HDSL2 delivers the same 1.5 Mbps service over a single copper telephone line.
HDSL2 also is designed to co-exist in the same cable bundle with T-1, HDSL, ADSL, and ISDN without interference problems caused by electrical noise.
PairGain's new Avidia interface provides eight HDSL2 T-1 connections, each transmitting at a 1.544 Mbps symmetric rate. The Avidia System has 18 slots for plug-in channel cards providing ATM concentration, traffic management, and QoS for up to 144 HDSL2 T-1 ports carrying voice, data, and video.