Software Application Redundancy; Figure 11. Typical High-Level Bladecenter Architecture - Aastra Clearspan Product Overview

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Each discreet server has dual power supplies, quad NIC interfaces and RAID disk drives.

2.2.2

Software Application Redundancy

System reliability is the result of more than just hardware compliance. Clearspan provides a total

system solution for redundancy that addresses potential points of failure in both the Clearspan

servers and the enterprise's IP network. This architecture, as described in the following section, is

designed to ensure that service is maintained in the event of a network and/or server failure.

2.2.2.1

Application Servers Redundancy

Application Servers are deployed in primary/secondary cluster mode. Under normal operation, the

primary Application Server handles all traffic. When there is a server or network failure, users are

automatically rolled over to the secondary Application Server on the next call (either originating or

terminating) that involves a subscriber. This ensures continuous access to normal calling for users.

The primary and secondary Application Servers are synchronized using the following mechanisms:



Cluster Data Replication: The Application Server TimesTen database is replicated

between the primary and secondary servers using TimesTen replication capabilities.

Subscriber data-sharing ensures proper behavior upon rollover of an access device to the

secondary Application Server.



Cluster File Synchronization: Announcements, voice mail greetings, web branding, and

other file-based configuration are synchronized using RSYNC, which is an open-source

utility commonly used to mirror Internet web sites.

2.2.2.2

Media Server Pools Redundancy

Media Server redundancy is accomplished through N+1 pooling. All Media Servers are

independent. A failure of a Media Server results in the Application Server timing out on attempts to

reach that server, and then routes to the next available Media Server.

Clearspan® Product Overview R19

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