MANHASSET, NY While the consumer electronics industry is yet to find a clear technology winner for digital home media distribution, some are clearly betting on Ethernet to become the answer for home networks by late 2009 and beyond.
IEEE 802 working groups are in the process of completing Ethernet AV, a set of modifications to existing Ethernet standards to make the protocol "rock solid" for transmitting streaming audio and video "with no clicks or pops," according to Rick Kreifeldt, vice president, Harman Professional Systems Development & Integration Group.
Today, common IT-oriented Ethernet networks, by design, use a best-effort protocol. They promise that data will traverse the network with zero errors, but offer no assurance that it will arrive in a timely fashion.
In contrast, emerging Ethernet Audio/Video Bridging (AVB) specifications -- consisting of 802.1AS, 802.Qat and 802.1Qav -- promise all of the following: 2 milliseconds guaranteed latency through seven Ethernet bridges; reservations for guaranteed bandwidth; and precise timing and synchronization services for timestamps and media coordination.
"There are two diverging drivers pushing Ethernet AVB," said Tony Jeffree, chairman of IEEE 802.1 Working Group.
One group, represented by companies like Harman and BMW, is hoping to build a standards-based reliable method of piping audio video for professional studios, concert stages and automotive applications, he said. Another is driven by Ethernet and WiFi router vendors, who hope to deliver low-latency, synchronized audio and video content to home networks, while taking advantage of lower prices for the already ubiquitous Ethernet.
Harman's Kreifeldt, for example, noted that his company is committed to rolling out Ethernet AVB-compliant products in all its business units -- including Harman/Becker Automotive Systems, Harman Pro Group and Harman Consumer Group.
Chip vendors such as Broadcom, Marvell and Xilinx are also reportedly eager to implement Ethernet AVB in their new Ethernet MAC hardware.
Of course, the IEEE AVB task group's effort is not the first attempt by the industry to develop a work-around for the lack of real-time support in the existing Ethernet.
DiffServ, for one, was created to add the concept of traffic priorities. Similarly, the industry developed the Real Time Protocol (RTP), a standardized IP-based method of delivering audio and video over the Internet.
However, neither attempt is satisfactory to Ethernet AVB proponents, because DiffServ does not guarantee end-to-end delivery of streaming data, while RTP, originally envisioned as a software application, is difficult to implement purely in silicon. Further, the larger stack required for RTP is said to make low-latency applications more difficult to realize.
Michael Johas Teener, plumbing architect / technical director at Broadcom, and chair of the IEEE 802.1 Audio/Video Bridging Task group, stressed, "Right now there is no interoperable way to guarantee bandwidth and latency, or to guarantee microsecond (or better) synchronization between endpoints on Ethernet, or on a bridged network consisting of 802 LANs. The AVB protocols allow all that, and, we believe, at a very small increase in complexity."
Further, the group developed Ethernet AVB to be "compatible not just with Ethernet but also with things that are not Ethernet," said Teener.