Failover To An Ess Server - Avaya ESS User Manual

Failover to an ESS server

Existing Communication Manager recovery mechanisms still occur prior to any failover to an
ESS server. For example, if a Main server loses control of a majority of Port Networks it may
attempt to switch to its standby server. This would happen before an IPSI would request service
from an ESS server. The response to a typical failover is:
The Main fails:
●
- Duplex servers:
a. Failure of the active server causes a server interchange. IPSI is still under control of
the Main server(s).
b. Failure of both servers causes a loss of communication to the IPSI. IPSI's no service
timer activates.
- Simplex server:
a. Failure of the Main server causes loss of communication to the IPSIs. IPSI's no
service timer activates.
The IPSI:
●
- Duplex IPSI:
a. Loss of communication between the active IPSI and the Main server(s) causes the
IPSI to interchange.
b. Loss of communication between both IPSIs and the Main server(s) causes the IPSI's
no service timer to activate.
- Simplex IPSI:
a. Loss of communication between the IPSI and the Main server(s) causes the IPSI's no
service timer to activate.
Note:
When an IPSI fails in an ATM environment, control falls over to an IPSI in another
Note:
Port Network without loss of service.
When an IPSI fails in a CSS environment, the Port Network is out of service.
During the no service time out interval, other existing failure recovery mechanisms
●
continue to be exercised.
- If the server(s) that last controlled the IPSI reconnects with the IPSI before the no service
timer expires, the IPSI will immediately request service from it.
If the no service timer expires, the IPSI requests service from the highest ranking ESS
●
server on its priority list.
Detailed ESS Overview
Issue 1.1 June 2005 19