Under the agreement, the companies will jointly promote and sell RealServer technology to customers of IBM's Unix-based e-commerce software, letting them use digital streaming to enhance their Web sites and internal communications, RealNetworks said.
The specific terms of the deal were not disclosed.
"Internet media helps e-businesses connect with their customers by adding an element of excitement and emotion to their online content," Tom Hull, vice president of media systems at RealNetworks, said in a statement.
For that Seattle-based company, the agreement means access to new customers as it faces competition from software kingpin Microsoft, which also offers server software. Microsoft's software works only with servers running Windows, which competes with Unix.
Last month, RealNetworks unveiled a similar deal with Hewlett-Packard to produce and sell servers that can be used to distribute streaming audio and video files.
IBM and HP also make servers based on Windows.
Unix servers built by Somers, N.Y.-based IBM recently were used to run the official Web site of this year's Sydney Olympics, the computing giant said.