Polycom® RMX 1800 Administrator’s Guide
5-14 Polycom, Inc.
Cascading Conferences - H.239-enabled MIH Topology
H.239 Multi-Hierarchy (MIH) cascading is available to Collaboration Server users enabling
them to run very large conferences on different MCUs in multiple levels of Master-Slave
relationships using an H.323 connection.
Multi-Hierarchy (MIH) Cascading is implemented where the cascaded MCUs reside on
different networks, whereas Star Topology Cascading requires that all cascaded MCUs reside
on the same network.
MIH Cascading allows:
• Opening and using a content channel (H.239) during conferences.
• Full management of extremely large, distributed conferences.
• Connecting conferences on different MCUs at different sites.
• Utilizing the connection abilities of different MCUs, for example, different
communication protocols, such as, serial connections, ISDN, etc.
• Significant call cost savings to be realized by having participants call local MCUs which
in turn call remote MCUs, long distance.

MIH Cascading Levels

The cascading hierarchy topology can extend to up to four levels (Figure5-5), where the
most common configuration includes up to three levels.
Figure 5-4 MIH Cascade - a Sample 3-Level Cascading Configuration
Although participants in MIH Cascading conferences can connect using H.323, SIP and ISDN, the
MIH Cascading Links must connect via H.323.