Product review: Casting files across WANs

What's the most efficient way to distribute frequent large file updates to dozens, hundreds or even thousands of remote sites on a network?

You could opt to send content via File Transfer Protocol (FTP), but that's time-consuming and inefficient. For more capacity, you could distribute CD-ROMs, but that takes even more time, is error prone and requires human intervention. And with FTP and CD-ROM distribution, there's no guarantee that updated files will be installed.

Unlike these older methods, StarBurst Software's OmniCast 1.01 is designed to distribute files to multiple users while preserving bandwidth on your WAN links. OmniCast is just the ticket for geographically distributed networks with unattended remote sites.

OmniCast delivers information to multiple recipients at a site in the same amount of time, using the same amount of bandwidth it takes to get files to just one. It implements one-to-many file transfers using three tools: broadcast mode in a LAN environment; IP Multicast on segments with multicast-enabled routers; and StarBurst's new FanOut technology on WAN links without multicast.

However, because it carries a $US39,900 price tag, OmniCast is most valuable for organisations that regularly distribute large amounts of data to multiple locations. For small networks, it may be more cost-effective to upgrade existing routers to enable multicast.

OmniCast is a logical extension of StarBurst's earlier MultiCast file transfer application. With MultiCast, you could select the files you wanted to send and define to whom you wanted to send them, and MultiCast pushed the files across the network to the recipients.

However, MultiCast was a point-to-point approach and not a true multicast application. Multicast (the concept, not the product) is a collection of standards that specifies a way to send data from one site to many sites on a network. Multicast technology allows you to reach hundreds or thousands of remote machines in such a way that any branch of your network topology tree has only a single stream of data travelling across it. It requires that you use routers that understand multicast protocols.

OmniCast delivers multicast capabilities without multicast routers. The product allows you to organise files into packages, which include instruction files that execute automatically upon receipt to perform tasks such as software installation. OmniCast compresses packages for more efficient transport over wide-area links. You can schedule package transfers to occur during off hours or at regular intervals.

Remote sites can receive data, and also unicast data back to the headquarters site on a regular basis.

FanOut is StarBurst's new technology that mimics multicast routing technology. It runs on one or more strategically placed NT Servers distributed across an enterprise network. OmniCast sends a package to a FanOut server, which unicasts to one or more downstream FanOut servers typically located across separate wide-area links. The FanOut servers multicast the content across the LAN or other wide-area links to other FanOut servers. FanOut servers allow you to multicast the same data to many clients located across a wide area, while only sending the data across a wide-area link once.

A FanOut server can also be the OmniCast server, except on the uppermost FanOut in the tree because of port contention issues. A single FanOut server can, at one time, forward packets to 256 downstream FanOut servers.

OmniCast has three components: the Dispatcher, Administrator Console and User Console. The Dispatcher runs in the background to send and receive files. The Administrator and User consoles are separate processes that can run on the same machine as the Dispatcher or on any machine on the network.

The Administrator Console is used occasionally to establish privileges for users and define policies and system parameters.You can specify transfer rates that differ depending on time of day or the available bandwidth during different periods. You also use this console to assign English aliases to each remote client and organise them into groups.

The User Console is the primary interface of OmniCast in which you organise files into packages and schedule file transfers.

The Dispatcher, Administrator Console and User Console run on Windows 95, 98 and NT 4.0. The OmniCast receivers on the downstream side run on a variety of platforms, including Windows 95 and NT, IBM OS/2, IBM AIX, Sun Solaris, Sun Interactive Unix v/386, DEC Alpha Unix, SCO UnixWare and SGI Irix.

OmniCast is a complex product. You must understand multicast technology, as well as the product itself and all its components before attempting to install it. Each component has to be deployed on an appropriate server on your network. We spent a lot of time poring over the documentation to get each component installed and configured correctly. However, when we did, we found a system for file distribution that beats anything available today. By implementing Starburst's FanOut servers, you can take advantage of OmniCast without having a multicast-capable network.

Multicast is an underutilised, common-sense technology that enables users with geographically dispersed networks to increase the efficiency of file transfers. OmniCast is the best multicast software product we've seen.

Williams is a freelance writer and product improvement consultant in Alpine, Utah. He can be reached via e-mail at Dennis@ProductReviews.com

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