Make way for multicast

Most audiences have yet to experience what has been hailed as the solution to sending live media streams over IP to large numbers of viewers -- multicast technology. Although it has been accompanied with due hype in network-savvy circles, few businesses have enough information about multicasting to make informed decisions about it -- how they can best understand employ the technology and reap the benefits of one of the most efficient ways to deliver content?

Multicast technology is a fundamentally different way to distribute media from the way we view streams today, which is via unicast technology. Simply put, multicast refers to a single stream that is delivered from a host and then replicated by the network at points closest to the viewers. In the unicast model a separate stream is sent from the source to each end user. For this reason, unicasting uses bandwidth inefficiently and bottlenecks occur because of the volume of streams sent out.

All this results in the common streaming problems, where networks become overloaded and media feeds fail. Multicasting solves these issues, although it must be remembered that ISPs currently derive their revenues by billing per megabyte of data. Multicasting would render this billing model redundant, pointing a finger in the direction of those slowing deployment.

Multicasting is an ideal way to deliver live content. Currently, the two most popular models of delivering content, caching and pushing content to the edge of the network and closest to the end user, both have latency accompanied with their delivery models. But multicasting can send a live feed continuously and instantly.

So, with all these great promises, why aren't we using multicast technology on the internet? Well, there are a number of reasons, the first being the cost to upgrade to a multicast-enabled environment. In order to deliver media in a pure multicast model, all of the routers, networks and end-user technologies must be upgraded. The upgrade would need to be made at all the ISPs as well as the client workstations, so it is a job with a substantial price tag.

Another inhibitor to multicast adoption is the inability for service providers to monitor audience behaviour in a multicast scenario. In unicasting it is theoretically simple to monitor the users' behaviour as there is an individual stream of data sent to each user. Audience monitoring provides valuable information to service providers including audience size and user response including advertising click-through rates. With this information, webcasters can show their advertisers a return on investment, which is increasingly important in the currently flat market of online advertising. Unfortunately, multicast technology as it stands today cannot offer this valuable information.

But that is not to say that multicast monitoring will not be possible in the future. Paul Hodgins, CEO of Virtue Broadcasting, the company that delivered Madonna's webcast from Brixton Academy, said: 'It will be possible to monitor the audiences, but right now it's really behind what we can do with unicasting.' Hodgins claims that developments for monitoring multicasting are underway by streaming giants including RealNetworks.

Another solution to the problem of monitoring audience behaviour in the multicast environment is to ask the user to fill in a direct marketing form when he logs on to view the content. David Radoff, director of corporate communications at Digital Island said: 'More businesses are moving towards getting users to do something online and getting a direct response or registration form filled in.' He added that American Express recently sponsored concert webcast events and asked users to apply for a credit card before viewing the concert, which was a highly successful way of registering new customers for the company.

Despite these solutions, multicasting is currently too problematic to be used successfully as an internet broadcasting tool. The largest inhibitor is the interoperability issue with all the points of traffic on the internet being multicast-enabled. Howard Appleton, technical services manager for Akamai Northern Europe said: 'There are about 7,000 ISPs on the internet and there is a lack of economic drive on their part to upgrade.' Of course, Europe presents it's own set of consumer problems as different incumbents overlap and geographical differences assert themselves. Over the past three years, multicasting has largely been developed and used within the corporate intranet environment. Hodgins agrees: 'In the enterprise it is technically more plausible to deploy multicast - we mainly see multicasting being used today over intranets and that's where it is successful.'

A number of enterprises currently use multicast technology for live keynote speech broadcasts, training and one-way conferencing. Within a corporation it is relatively easy to ensure that the network and end users are multicast-enabled, so the interoperability issues are resolved. As an additional benefit, businesses using multicast do not waste their precious bandwidth, which makes a multicast upgrade worth the investment. Radoff said that Digital Island multicasts for Cisco Systems, which uses its intranet for e-learning events for its employees.

In the future, multicasting will undoubtedly become more popular, and is likely to cross over from intranet into internet broadcasting events. Hodgins explained: 'Eventually, multicasting will be adopted, it just makes sense for live broadcasting. But I don't see it happening for about 2 or 3 years.' Many of the network operators are installing multicasting equipment, including Interroute, one of the largest pan-European IP networks. Until multicasting becomes more widely adopted, businesses will continue to throw away bandwidth to resolve the issues of the poor quality audiences receive from live media streaming on the internet.

And overall, the decisions have to be based on sound business models. Said Radoff: 'It is a question of economics. How many big live events are there a year, and will you have enough customers? This year we found that on demand media was far more popular with our customers.' Digital Island has its own private network, and Radoff said that if the company was to upgrade to multicast, it would install the technology on that network. He concluded: 'We are evaluating multicast technology for our network, but I don't think we've said if we have committed to it yet.'

A mixed message then - while clearly the way forward for webcasting to large audiences, the technology seems to be in front of market demand, as usual. Whether business demand will force ISPs into adopting it is yet to be seen, but as multicasting attacks their revenue streams, this seems unlikely in the short term. This said, if enough corporations accept multicast as a defacto, then ISPs may have a harder task to defend their position -- it seems there is all to play for. Louise Carroll

Interested in this topic? Check out the Streaming Media Europe 2001 Media and Entertainment conference track!