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Managing the flow of streaming media

August 6, 1999
Web posted at: 10:30 a.m. EDT (1430 GMT)

by Jason Meserve

Network World Fusion

(IDG) -- As end users demand more multimedia on the network, network managers are faced with the dilemma of how to upgrade their networks to handle it.

The easiest solution on the LAN is to throw more bandwidth at the problem. But if you're dealing with a WAN and large numbers of geographically dispersed users, this solution is impractical.

That leaves the option of managing your existing bandwidth.

"None of this stuff is going to fly unless there is some sort of measure to protect the integrity of the network," says Andrew Davis, managing partner at Wainhouse Consulting Group in Brookline, Mass. "There needs to be a limit on the number of simultaneous users and the amount of bandwidth being sucked up. Without these limitations, no sane network administrator would deploy streaming media because they're afraid of a crash."

ISPs are typically more concerned with live broadcasts bogging down a network, such as the Victoria's Secret broadcast earlier this year. But enterprise managers tend to worry more about video-on-demand applications, says Amit Pandey, director of NetCache marketing for Network Appliance.

For video-on-demand applications, the key is to get the content as close to the end user as possible. Theoretically, the less distance a stream has to travel, the better the quality will be. But while this sounds simple enough, actual shipping products to distribute streams across a network are few and far between.

SightPath of Waltham, Mass. is shipping a suite of tools for pushing rich media content out to the fringes of the corporate network. The SightPath Studio collects standard media (MPEG 1 and 2, Real, Microsoft Media Player, QuickTime and others) for distribution to SightPath Appliances, which sit on the local area network and can connect up to 20 simultaneous viewers.

The key to the appliances is that content can be pushed down to them overnight, when network load is typically at its lowest. End users connect via a standard Web browser and media player (such as RealPlayer and Microsoft Media Player.) Each connection request is directed to the nearest SightPath Appliance.

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StarLight Networks, meanwhile, offers a "traffic shaping" middleware tool called StarWorks that is designed to keep streaming data flowing at a constant rate. StarLight's technology layers on top of standard streaming media protocols and breaks data into the right size pieces so that data may be sent across the network evenly.

"Spikes and stuff are what bog down the network," says David Edwards, vice president of engineering at StartLight in Mountain View, Calif.

Internet Video Technologies Burstware product streams data to a PC, creating a localized cache on the fly. The technology uses the maximum bandwidth allocated to send on-demand video down to the client as quickly as possible.

Burstware uses a server, conducts that sit on the network and monitor performance and a proprietary player for viewing and listening to streaming media. The player supports MPEG, QuickTime, MP3 and WAV formats. The server and conductors sit on either a Sun Solaris or Windows NT 4.0 server, while the player is available for Windows 95, 98 and NT.

Though Burstware began shipping back in February, it is still in early adopter phase. TVN Entertainment, a pay-per-view movie service provider in Burbank, Calif., recently licensed some of Burstware's technology for possible use in its operations.

"We're doing the final evaluations of the Burstware product," says Greg Pasetta, a senior vice president at TVN. "Like the economies of it and the way it can manage bandwidth."

Pasetta is looking at it as a way to manage the pipes between his organization and the cable head ends that his company services. Right now, the company is multicasting single events down to cable companies using its own network of 15 satellites. Pasetta hopes Burstware will enable him to better mange his bandwidth and send down multiple files to multiple clients.

Working with RealNetworks, Inktomi has developed a Media Cache option for its Traffic Server product. Version 1.0 of the Media Cache stores Real media at the LAN level. When a user requests a file, the cache is checked first at the LAN level, if the file exists, it is streamed directly from the cache.

If the file is not in the cache, the request is passed on to the origin server where it is delivered to the end user via the cache. The file is then stored for future use at the local level. The Media Cache contains the RealServer G2 enabling it to stream at levels ranging from 28.8K to broadband.

"When you stream to all end users you need to replicate the stream for each employee or customer," says Inktomi's Haslam. "Instead, you can carry the stream once across the network to our cache, saving bandwidth and keeping your infrastructure investment. The end user is not subject to delay between them and the origin server."

Haslam says the cache has built in intelligence to keep files up to date. It can utilize an encrypted back-channel connection for "chunking" files down to the cache quickly. Using a proprietary administration protocol the cache can connect back to a RealServer G2 to authenticate and validate users before delivering content.

Network Appliance is working with Microsoft on a similar offering that supports the Media Player technology. NetCache is a hardware-based system being built from the ground up, says Network Appliance's Pandey.

"We're building this from the ground up by taking select elements of the server, only what is necessary for an end-point cache and streaming," Pandey says. "We don't want to put the whole server on a box. If you look at most streaming servers they are huge, somewhere around one million lines of code. Taking all that code and putting it on a box is extremely inefficient."

Pandey says NetCache just entering the demonstration phase with a commercially available product shipping late this year.

While Inktomi and Network Appliance are only supporting one format at the moment, both expect to expand to other formats in the near future.

Live, from New York...

The current Internet fad of live broadcasting will begin to sweep corporate networks. CEOs with far-flung outposts can use the technology to give briefings and state-of-the company addresses.

For live video, there are basically two management options: IP Multicast or signal splitting.

In a multicast network, a single stream is sent out to a single session address. The stream is then routed to all subnets that have clients requesting to view or listen to the broadcast. Multicast-enabled clients, such as RealNetworks RealPlayer, need only tune to the specified multicast address. Multicast can support thousands of users with a single stream.

In a standard streaming model, each client would attempt to connect to the server resulting in one stream per client, or unicasting. Without a high-powered server and a fat pipe through the network, unicasted live events quickly degrade under heavy load.

Many agree that multicast is the way to go when doing a live broadcast across the network. The only problem is the entire network of routers must be multicast-enabled. This is easy if one owns the entire network and can ensure multicast availability. But for streams that must travel across the Internet, multicast is no longer a viable option, as there is no way to ensure that each router in the path is multicast-enabled.

Multicast Backbone (MBone) is an experimental overlay network that allows for IP multicasting across the public Internet. However, because MBone is a volunteer cooperative, its commercial use is limited.

The Pentagon uses IP multicast internally for its broadcast, with unicasted streams supporting remote outposts and users, says Connie Leonard, chief of the Web and electronic conferencing division with the undersecretary of defense for acquisition and technology. Last month Leonard's group supported 16 streamed events over a five-day period as part of the Pentagon's "Acquisition and Logistics Reform Week."

Leonard estimates roughly 3,000 people tuned into the events over the Internet. For the most part, content was streamed out at 28.8K, save for a few people that could support 100K bit/sec streams.

"In a number of cases with the military out in the field, their networks cannot accommodate a lot of connections though the Internet, so for them there were some network restrictions that would not allow them to participate," Leonard says.

She hopes that over time, more of the sites will become multicast enabled, allowing her group to provide more services for distant end-user communities.

A splitting image

Splitters provide an alternative to IP multicast for live broadcasts by taking a single stream coming from the origin server and splicing it into multiple streams at the LAN level based on client demand. In this case, a single stream is sent across a WAN or the Internet to the splitter, where it is rebroadcasted into multiple unicast streams across a LAN.

Local users are connecting to a device on their high-speed LAN, not connecting all the way across a slower WAN or Internet connection. This allows the origin server to service more users, since clients are connecting to local servers to receive broadcast. Splitters merely redirect broadcasts, they do not cache them for on-demand viewing.

RealProxy from RealNetworks is one of the few solutions available for splitting live broadcasts. Available commercially as an option to the RealSever G2 or as an SDK for third party developers, RealProxy pulls in one stream and can replicate it out to many clients using unicast or multicast, according to Brian Cohee, product manager of core technologies for RealNetworks.

"You can't pull multiple 1.5 megabyte streams across the Internet or you'll get a lot of packet loss," Cohee says. "[With RealProxy] pull in one pristine stream and split out to other clients."

RealProxy offers a work around for users wanting to multicast across the public Internet. The software includes a lightweight accounting connection back to the origin server to validate client access and track viewership, Cohee says.

"Quite frankly, a lot of companies that I've talked to say, 'Ok, [streaming media] is great, we understand it will save us money ... but we need help deploying because of the network issues,'" Davis says. "All the HR managers are wanting this stuff, but the network administrators are swamped."

Davis hopes that as the year 2000 passes more companies will have the resources and mind set to start focusing on new applications and technology, rather than worrying about the Y2K problem.

By then, most of the caching/bandwidth management technologies being developed or released should be mature enough for the enterprise space.

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July 23, 1999
Apple tackles Net TV
July 22, 1999
Ethernet alternative makes streaming video affordable
June 18, 1999
More jobs for streaming media
May 12, 1999
Microsoft launches its answer to MP3
April 15, 1999
Find streaming media on the Web
March 22, 1999

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