DLNA Basics

Two obstacles help explain why so few consumer electronics (CE) devices are networked. First, home networks are less widely deployed than one might imagine. Second, standards to allow disparate CE devices such as TV sets and stereos to communicate have been slow to arrive.

The Digital Living Network Alliance (DLNA) is changing that game. Founded in 2003 by Sony and Intel and originally called the Digital Home Working Group, DNLA aims to promote wired and wireless interoperable networking of PCs, CE and mobile devices.

Some 220 member companies support the Alliance, including the top 10 CE manufacturers and the top five chip manufacturers. Twenty-five companies serve as "promoter members," including Comcast, whose New Media Development Group joined in March 2007. Time Warner Cable is listed as a member company.

The Alliance has matured to the point where several CE devices in 2006 were certified with DLNA logos, meaning these products will work with other DLNA-certified products of other manufacturers. The Alliance also has four test labs, located in the United States, Japan, Belgium and Taiwan, and seems to have geared up for an onslaught of new devices seeking the certification. What is DLNA? As a CE communications standard, DLNA represents the content negotiation and sharing portion of a much broader Universal Plug and Play (UPnP) standard that deals with the lower level intercommunications between disparate networked devices.

A DLNA device works like any other network device by discovering other DLNA-enabled hosts, but then goes on to learn their capabilities and exposes these features on the device’s control display. Through DLNA, a media server can be located and then summoned to play or display a stored family photo, movie, music file, etc. That is the extent of the v1.0 DLNA specification.

Think of a DLNA server as a multi-room digital video recorder (DVR) on steroids. Moreover, it’s one that a subscriber can buy in interchangeable devices from a host of vendors. In fact, DLNA’s second specification (v1.5), released in late 2005, defines 10 new device classes.

In the future, as DLNA’s technical capability and vocabulary expand, the spec will add digital media printing and the ability to push images to a network attached storage (NAS) device, manage media with a mobile device, and leverage quality of service (QoS) between devices. Already, however, a consumer who purchases, say, a DLNA-certified Blu-ray Disc (BD) player and exposes it to a home media server can easily switch between a high definition (HD) movie and some other media accessible over a home network. So what? For decades, CE devices haven’t worked together, so why should that change now? For one, it’s already changing. Consider the high-definition multimedia interface (HDMI). (See the May 2007 issue of Communications Technology for more on HDMI.) Before HDMI, each manufacturer developed its own proprietary cables and signaling (e.g., Panasonic’s HDAVI and Pioneer’s SR) that none could ever agree upon.

With DLNA, the CE industry is working together again, using standard networking (Ethernet) and requiring interoperability testing to use the DLNA logo. Using Ethernet allows CE manufacturers to build upon existing standards, silicon and know-how to enable rapid development

DLNA’s vocabulary and installed base should expand dramatically in the coming years because of the rising interest in networking CE devices in the home, especially because DLNA is a desirable feature of any new CE device that hosts either an Ethernet jack or has built-in Wi-Fi.That makes it something that cable operators – and broadband service providers of all stripes – will put on their near-term radar.

Just as operators have increased the number of programming choices and on-demand and interactive options, they can also help expand and extend DLNA to increase consumer choices. Together, DLNA and UPnP provide a nest of interoperable and inter-accessible technology within each networked home, essentially creating a desirable island of rich media functionality within the home. New bridges The types of bridges that are possible with DLNA, however, may differ significantly from legacy bridge offerings.

Today’s video, wireless, voice, and even Internet services all maintain a fairly significant data center management component that requires integration above the data center to bridge features of one service to another. The conventionally understood way to bridge these services requires a physical technology bridge, such as IP Multimedia Subsystem (IMS), to connect one service to another; an operations/business support system (OSS/BSS) bridge to package, activate and bill for these services; and finally, one or more service-specific communications bridge(s) for various service elements to communicate with each other to produce the desired functionality (while preferably not interfering with another service).

This process ends up being rather complicated and formalized, which is why you don’t see cross-service functionality rapidly flowing out of service provider development shops.

The bridging of DLNA devices, however, is "opportunity based" in that it merely requires the presence of two or more DLNA capable devices on a home network. Those devices could include telephones, fax machines, home security systems, TV sets, stereos, set-top boxes, along with more traditionally networked devices such as computers.

The scope of possible devices could make DLNA appear as something of a threat, the flexing of CE manufacturers’ muscles to show that bridging services can just as easily happen within the home as in the data center. It also could reduce the bridging-role of service-provider equipment such as the set-top box or modem. Perhaps more importantly, once networked, other DLNA devices could bridge this network of devices to other Internet-based services, such as I-Tunes, MovieLink and others.

As service providers of all stripes place DLNA equipment in the home (including set-top boxes), consumers will use it over time, rather than immediately. This creates a look-ahead opportunity, or innate capability, waiting to be tapped.

Currently, DLNA creates an island of networked media within the home – just begging to be taken to the next level. While DLNA has aspirations to connect to the unmanaged Internet, this is beyhond its current scope and presents a unique opportunity. Here’s a set of recommendations for embracing DLNA, expanding its current vocabulary and extending its uses outside its currently restricted domain:

• Continue engaging with the standards group to ensure that their devices placed in consumer homes adhere to DLNA. The key is to push the envelope of DLNA capabilities that would increasingly leverage their penetration of premium services, such as HD content.

• Enable user interfaces to discover other DLNA equipment available on the consumer home network, such as digital surround receivers, and give consumers the option to route the sound of their TV programming accordingly.

• Extend DLNA by hosting ultra-reliable, virtual DLNA devices such as media servers that offer consumers such benefits as lifetime storage for media, continuously updated DLNA capability, and even restricted sharing or bridging between two or more subscriber homes.

• Implement DLNA on digital phone service or provide translation bridges between DLNA and other lower data rate communications such as ZigBee to further open up the home for increasing innovation. Treasure chest DLNA is an opportunity for service providers to assert themselves as the masters of media within consumer homes at a time when CE manufacturers are beginning to open up their "treasure chest" and expose all their goodies for someone to finally pull it all together into one cohesive system.

The key here is that the TV set – or home theater system – is still the center of entertainment and represents the highest quality viewing or listening experience within the home. In recent years, the PC has challenged these occasionally, but it just can’t deliver the same entertainment quality.

DLNA creates the bridge for these personal and portable media to flow back into the TV set and home entertainment system where they can be enjoyed to the fullest extent possible.

Portable media will still have its place, as will the PC, but trend-setting audiophiles and videophiles see the dust settling around more traditional uses for CE devices like the stereo and the TV set. DLNA only modifies these devices slightly by extending them and has the capability to be the fundamental cornerstone that will lead to simplifying the interoperability of devices and media applications within the home. Bruce Bahlmann is VP Data Technologies at Sedna Services.