Timing considerations
Issue 1.1 June 2005 83
In this example, the failover scenarios in Table 6 might occur:
Timing considerations
Depending on your configuration, there are a number of timers that are used during a failover.
After failover, conflict with the timers may produce a configuration that you did not want or
anticipate. This section describes the following timers:
● ESS no service timer on page 84
● H.248 server-to-gateway Link Recovery on page 84
● H.323 gateway-to-endpoint Link Recovery on page 87
Table 6: Multi-Connect using ATM PNC
Failure type failover description
Main server(s) fails ESS server 1 is the highest ranked ESS server on the
IPSI priority list. All Port Networks failover to ESS server 1
including those without an IPSI.
Both Main server(s) and ESS1
fails
ESS server 2 is second highest ranked ESS server on the
IPSI priority list. All Port Networks failover to ESS server
2.
Control network fails The Main server(s) continues to control PN1, PN2, PN6,
and PN7. In addition, the Main server(s) takes control of
PN4 and PN5 through the ATM network. ESS server 2
takes control of PN3.
Main server(s) fails, WAN
connection fails, and ESS
server 1 fails
PN3, PN4, and PN5 failover to ESS server 2 as it is now
the first ESS server on their priority lists. ESS server 2 is
not available to PN1 and PN2 over the WAN but ESS
server 2 can support PN1 and PN2 through the
connections to the ATM network.
Main server(s) fails first and
then control network fails
PN1 and PN2 request service from ESS server 1. PN3,
PN4, and PN5 request service from ESS server 2. ESS
server 1 will be the first to try to take control of PN6 and
PN7 through the ATM network. This however, is timing
dependent. There is some possibility that ESS server 2
might control PN6 and PN7 instead.
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