Mitel MiVoice Manual page 17

Figure 10: Daisy-chained MBGs to save bandwidth
The upstream server can be deployed in either a Gateway or a DMZ configuration.
Warning: Management of all remote office sets must be done on the upstream (main office) server only.
When the downstream server is put into mode, it will automatically disable all MiNet and SIP connection
restrictions, and pass all connection attempts up to the upstream server for authentication.
The remote office (downstream) MBG can also be configured for either a Gateway or DMZ deployment. Note
that there is no restriction on the location of the remote office sets; they do not have to be on the LAN. It may be
desirable to configure certain teleworker sets to connect to remote office MBGs (rather than the main office
MBG) in order to cause direct of those teleworkers' calls to sets in the remote office. This case requires Local
streaming to be enabled on the upstream (main office) server.
It is even possible to deploy multiple downstream MBG servers at different remote offices. If upstream (main
office) server has Local Streaming enabled, calls within each remote office remain local to that office: signaling
still flows back to the main office, but voice streams for calls between offices will only traverse the path between
the two MBGs. This minimizes bandwidth use on the main office's connection.
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