ESS Design and Planning
76 Avaya Enterprise Survivable Servers (ESS) Users Guide
Examples of how the priority list works
The following examples demonstrate how the IPSI priority list is used during failover scenarios.
IP connected Port Networks
In this example, an IP connected system has five IPSI connected Port Networks and four ESS
servers. During the planning phase, the administrator decided that:
● The primary goal was to keep as much of the system in-tact as possible. In order to
achieve that objective, two ESS servers (ESS server 1 and ESS server 2) were placed in
the network. Both ESS servers backup the Main server if the Main server fails, or if
communication from the Port Networks to the Main server fails.
● If the WAN fails where Port Networks 3, 4, 5, and 6, can no longer communicate with the
Main server or ESS server 1:
- The Main server will control Port Networks 1 and 2
- ESS server 2 will control Port Networks 3, 4, 5, and 6.
● If LAN 3 fails where Port Network 3 can no longer communicate to LAN 2, ESS server 3
will service Port Network 3.
● If the WAN fails where Port Network 6 can no longer communicate with servers outside its
community, than ESS server 4 (the Local Only server) will control Port Network 6.
See Figure 28
for the customer’s configuration with the priority scoring of each ESS server.
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