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For phase 2, pbx3 with IP address is replaced with a server with IP address on the separate subnetwork. The same test strategy for phase 1 is then used for phase 2. The router is instrumented with a bandwidth measurement tool to estimate the amount of traffic used to replicate state information from the voice servers in the primary 10.20.2.x subnetwork to the secondary 10.10.17.x subnetwork. This insight is important to understand the WAN bandwidth impact if the intent is to geographically distribute some of the secondary voice servers in multiple locations.

By design Sipxcom is designed is always use its built-in DNS server for querying SRV records - the Sipxcom unmanaged DNS server option when enabled allows querying of an unmanaged DNS server for phone registrations.   In testing the Sipxcom HA solution in release 16.12, difficulties were encountered using the managed DNS tools of Sipxcom. This document provides a good overview of the Sipxcom managed DNS capabilities and how they should work. Significant investments were madeto made to make Sipxcom DNS management tools work with the high availability solution -  the HA solution performed best in the lab when Sipxcom used a DNS server that was completely separate from Sipxcom, i.e. DNS services on each of the Sipxcom servers was disabled.  The first part of this document assumes that Sipxcom uses a separate DNS server for all SRV record processing - to do this, careful attention needs to be placed on how Sipxcom primary and secondary servers are built and to disable the DNS service from being enabled at startup. The second part of this document describes how the HA solution works using the managed DNS tools available in Sipxcom.

Note: eZuce recommends DNS be configured on each server. Separate DNS servers require manual management and can degrade Proxy & Registrar performance. Where phones get DNS from is a wholly different issue than where the servers get DNS from.

Configuring Sipxcom for High Availability using Standalone DNS servers

These next few subsections assumes assume that a new Sipxcom server is being built from scratch, a separate DNS server is used for all Sipxcom DNS processing, and that DNS is turned off on all Sipxcom servers.


Build the primary Sipxcom server using the IP address  address as the primary DNS address in the Ethernet network settings - otherwise, Sipxcom will override any manual entries in the /etc/resolv.conf whenever the primary Sipxcom server is restarted. When the fresh Sipxcom system is started, check the primary External DNS setting to ascertain that it points to the standalone DNS server built in the previous step; Otherwise, the etc/resolv.conf will need to be updated to point to the standalone DNS server after every reboot. Start all all necessary Sipxcom services except Sipxbridge, which is not supported in the HA configuration.