Management of I-Mux channels is as important as management of dedicated channels. Most inverse multiplexers support Simple Network Management Protocol (SNMP), including both public Management Information Bases and, often, the I-Mux manufacturer's proprietary MIB. Additionally, since inverse multiplexers establish temporary dial-up circuits, some form of security is a must. Security in typical inverse multiplexers includes password protection, dial-back, address restrictions, and packet filtering, which is based on predetermined inter network profiles.

MUX Makers There are a few well-known manufacturers of inverse multiplexers, and they are generally categorized according to the bandwidthplace they support. One of the earliest pioneers in the field of inverse multiplexing is Ascend Communications. Ascend's products tend to operate in the low range of bandwidths, creating composite circuits of up to four T-1 or ISDN PRIs. They also work at the Switched 56 level. At the higher end of the bandwidth spectrum, Digital Link (Sunnyvale, CA) creates T-3 bandwidth using multiple T-1 (up to eight) lines with its DL 3800 I-Mux. T3Plus Networking (Santa Clara, CA) also works at this high end. However, T3Plus takes T-1 to T-3 inverse multiplexing a step further, with emerging support for Asynchronous Transfer Mode (ATM) and Synchronous Optical Network (SONET) bandwidths. SONET will eventually allow bandwidths of up to 155Mbps as the transmission foundation for ATM transport-layer services.

Telco Systems (Fremont, CA), like Ascend, operates at lower bandwidths, combining up to 24 Switched 56 circuits. Videoconferencing is a key application for both Telco and Ascend. Inverse multiplexing can accommodate the sometimes high-bandwidth requirements of video by bundling lower-cost, lower-bandwidth channels into a pipe that sufficiently supports the video conferencing requirements. When the conference is over, the lines are released, saving significant money over full-time, dedicated, high-bandwidth circuits.

Globand and Bonding Inverse multiplexing techniques are becoming popular worldwide. Several countries have adopted a set of standards for bandwidth-on-demand 64Kbps services. These services, generically called Global Bandwidth on Demand (GloBanD) operate under different names in their respective home countries. Belgium, Denmark, Hong Kong, the Netherlands, Switzerland, Norway, Portugal, and Finland, to name a few, have set up formal GloBanD services. Many can be reached via MCI's international switchboard. In all countries but the United States and Hong Kong, GloBanD access is via European E-1 circuits (2.048-Mbps). In the United States and Hong Kong, access is via T-1 (1.544 Mbps) lines.

In addition to GloBanD, several inverse multiplexer manufacturers, representing the United States and Europe, have banded together to form BONDING--the Bandwidth On Demand INteroperability Group. These companies, including 3Net (Rancho Cordova, CA), Adtran (Huntsville, AL), Ascend, Newbridge (Herndon, VA), Promptus (Portsmouth, NJ), Telco Systems, Teleos Communications (Eatontown, NJ), Tylink (Norton, MA), and Motorola-UDS (Huntsville, AL), aim to develop a BONDING specification against which inverse multiplexers may be tested for compatibility between manufacturers. The standard has been approved by the Telecommunications Industry Association and is awaiting the approval of ISO.