The IMUX-56/64 Module combines multiple ISDN B-channels using the BONDING Mode 1 protocol to support high bandwidth ISDN applications such as dial backup of Frame Relay or dedicated circuits. The BONDING capacity of the module is 60 DS0s or ISDN B-channels, which can be allocated according to the user's needs. For example, an ATLAS system can be configured toCONNECT eight B-channels USING BONDING as a dial backup link to a remote 512 kbps ISDN device, such as the ISU 512. Similarly, the module might be configured to implement two sessions at 512 kbps, 1 at 384 kbps, and 6 at 128 kbps. Table 1 shows how many sessions can be supported at typical BONDING rates.The IMUX-56/64 Module has no external network or user interfaces. Network traffic is passed to it though other ATLAS modules such as the Octal BRI Module or the Quad T1/PRI Module. Similarly, traffic is passed to the user through modules such as the Quad Nx56/64 module. This partitioning allows the BONDING module to serve as a resource for multiple user devices. When combined with the ATLAS 800PLUS and Frame Relay software, the Nx56/64 IMUX module can offer high speed dial backup around the network in Frame Relay applications. This same capability can be applied to providing dial backup of failed dedicated circuits or other network connections. Other applications that may call for the IMUX-56/64 Module include image transfer and video-conferencing. The IMUX-56/64 Module is compatible with the ISDN dial backup options of ADTRAN's Express 5000 series products as well as the IQ family of frame monitoring CSU/DSUs. It is also compatible with ISDN access products such as ADTRAN's ISU 128 and ISU 512, as well as the ISDN dial backup options of the TSU family of T1 access devices.