Specifications

MBG Engineering Guidelines, Release 8.0
10.4 Additional Considerations
While heterogeneous server capabilities are supported in a cluster thanks to the weighting mechanism, this
weighting only affects the number of connected devices on each server. The cluster communications adds
additional load on each server, so adding a node to the cluster does not, necessarily, linearly increase the
capabilities of the cluster.
Furthermore, if the master node is used as the initial point of contact for all devices, then it should not be a
“weak” server. There are many supported devices that do not support redirection, so the server they are
programmed to contact will be the only server that they connect to. Setting a low weight on the main node will
not change this. All SIP devices, MiNet softphones, and 5550 IP Console fall into this “non-redirectable”
category. Such devices must be balanced manually by programming the devices to contact specific
nodes. Setting a low weight, or a weight of zero, on nodes that handle non-redirectable devices can help with
manual load balancing.
10.5 Firewall Configuration for Clustering
When MBG is deployed in the DMZ, the corporate firewall protecting the DMZ requires the following rules (in
addition to the common rules found in Firewalls (DMZ deployment)):
From each MBG server to all other MBG servers in the cluster:
• allow protocol TCP, destination port 6809
Note: This is a minimal configuration. Refer to Appendix A: Firewall Configuration Reference for the full set of
rules and optional settings.
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