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What is Imux?

Imux is an abbreviation for Inverse Multiplexing.

Multiplexing is a process of creating multiple data streams from one data stream. Inverse multiplexing is the opposite.

In communications a common multiplexed circuit is a T-1. Taking a 1.536Mbps data stream and breaking it into multiplexed 64Kbps circuits provides 24 individual data paths. A single data path can be used to carry a single phone or fax call. Video conferencing systems, however, in order to send enough bandwidth between one another to create moving video images in some degree of quality, require more than one such 64Kbps data path. Inverse Multiplexing or Imuxing enables this aggregation of multiple data paths into larger data paths.

How does an Imux work?

An inverse multiplexer or Imux uses an algorithm to aggregate data channels together. This algorithm when applied to H.320 use of switched digital circuits is called Bandwidth On Demand, or BONDING.

To understand what BONDING is, first it is important to understand that H.320 is the ITU recommendation for video conferencing using ISDN networks. ISDN or "Integrated Services Digital Networking" is a form of digital communications that can provide up to 64 kbits/second of bandwidth per ISDN channel.

In order for video conferencing systems to use ISDN to deliver dial-up digital bandwidth, some form of reverse multiplexing or bandwidth aggregation technique is required.

BONDING algorithms do this. These algorithms allow Inverse Multiplexing of channels to create call sessions in bandwidth increments of 64kbits/second. BONDING stands for "Bandwidth On Demand" and several Bonding algorithms were developed to create aggregated high bandwidth ISDN calls. BONDING is essential to H.320 video conferencing above 64Kbps.

What do I need to know about an Imux?

Imuxing is the use of BONDING as an aggregation technique to create higher than 56Kbps or 64Kbps call paths. In the Imux/BONDING process, individual calls are initiated and then aggregated. Of all the calls made in this process, the first call is the most significant. The Imux process requires at least one single call path to be successful before other call paths can be connected to it.

Therefore, in an H.320 environment, video conferences that fail to connect due to a BONDING or Imux failure may well have a problem with the first call connection. If you experience this failure type in your business organization, contact TKO VideoConferencing for assistance and we may be able to assist you.

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