CallXpress supports a wide range of features deigned to making it extremely reliable. Hardware components, software, architecture and monitoring systems are all involved in the CallXpress platform reliability strategy, Below are some of the more important reliability features in CallXpress.
Feature Name: High Reliability Architecture Dependencies:
Feature Description: CallXpress achieves a high level of reliability through focus in several areas. Each of these areas address a different aspect of reliability.
First, AVST recommends using high-availability hardware to deploy the CallXpress system. Like any mission-critical application, the voice and unified messaging application can benefit from servers configured with RAID drives, redundant hardware elements (fans, power supplies, CPUs, etc.) and power backup options.
Second, the CallXpress installation guidelines specify a method of installing CallXpress that will maximize the reliability of the server. AVST recommends no software other than CallXpress and its supplied components is in installed on the server. This ensures that no other software can affect the reliability of the system. The exception to this is that we highly recommend that the enterprise runs its normal virus protection, patch maintenance and backup programs to help ensure the health of the system.
The third method used to enhance system reliability is the architecture used to deploy the system. While most CallXpress systems can be deployed on a single server, it is also possible to deploy a system using redundant and load-sharing components. By using multiple servers, CallXpress can be configured so that no single hardware or software failure will cause the system to fail. CallXpress supports multiple Call Servers that connect to the telephone system for the purpose of answering and making calls. By splitting the application across multiple Call Servers, if a single Call Server fails, while there may be a reduction in capacity, the system continues to function. Systems can even be configured with warm standby Call Servers that can quickly be brought on line to restore the system to full capacity. As an option, a system can be configured with a hot standby System Server. This active-passive server arrangement means that in the event of the failure of the main System Server, the hot standby System Server will automatically assume all of the responsibilities of the system keeping CallXpress on line and fully functional.
The fourth way in which CallXpress maintains a high level of reliability involves using a comprehensive set of server and processing monitoring tools to help monitor the current health and status of the system. CallXpress supports a suite of monitoring tools designed by AVST to test and monitor all of the critical system processes as well as supports a full set of SNMP tools allowing the system to be monitored from the customer’s existing data center applications.
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Feature Name: SNMP Support Dependencies:
Feature Description: CallXpress supports the use of Simple Network Management Protocol (SNMP) to
monitor and maintain the CallXpress server. CallXpress includes an extension agent which can provide management information about the CallXpress system to any SNMP management console. CallXpress supports both management info base (.mib) and trap definition (.tdf) files. Once the extension agent has been installed and a management console has been configured to manage it, administrators can use it to manage CallXpress from another computer on the same LAN or WAN. The SNMP package can also be used to manage the Automated Agent and Digital Networking features if they are installed on the system.
Feature Name: High Availability Architecture Dependencies:
Feature Description: CallXpress is designed to be a highly reliable system. The following attributes and features contribute to its high reliability nature:
Support for High Availability Hardware…CallXpress has been designed to take advantage of today’s high availability server architecture. CallXpress systems can be deployed on servers supporting the hardware reliability features such as:
- RAID drive arrays
- Redundant hot-swappable power supplies - Redundant hot-swappable cooling fans
Multiple Call Servers… CallXpress systems can be deployed with multiple Call Servers which gives the system a high level of survivability. In a system where multiple Call Servers are connected to a single telephone system (such as using two 24 port Call Servers instead of a single 48 port Call Server), there is built-in fault tolerance by virtue of the fact that each Call Server can function independently of the other. In such a system, if any of the system Call Servers fail, there is some reduction of capacity (in the case of the example described above, there would be still be 24 ports left to handle incoming calls), but there is no loss of
functionality. By careful programming of the telephone system (hunt group), the system would be left capable of handling most incoming traffic. In many cases (SSE, IP, T1 and QSIG
integrations), the failure of a Call Server would busy out those extensions associated with it, moving all traffic to the remaining Call Server(s).
Survivable Call Server… In a deployment where the Call Server(s) are on separate physical servers from the System Server, if the System Server fails, the Call Servers continue to function. There is a loss of some functionality but the following functions continue even without the System Server:
- Answer calls with full integration - Process all Call Processing applications - Process all Presence\Availability solutions - Play all announcements, greetings, names.etc. - Record messages
Messages taken on the Call Servers when communications with the System Server are disrupted are cached on the Call Server. Once communications with a functioning System Server is restored, the messages are moved to the System Server and posted to the message database. Subscribers will not be able to log into their mailbox until the connection to a functioning System Server is restored. When subscribers call into the system, they will be notified that login services are temporarily unavailable.
Hot Standby System Server… As an option, CallXpress can be installed with an optional Hot Standby System Server. This hot standby System Server contains an up-to-date copy of the full database from the active System Server. All changes made to the System Server are
automatically replicated on the backup server. This includes program changes, software updates, user messages, recorded names, greetings and announcements, etc. The backup server also runs a program that is monitoring the health of the System Server. By monitoring certain critical functions and services, the backup server can tell the general health of the System Server. In the event that the backup server determines that the System Server is no longer functioning at a sufficient level, it takes steps to replace the System Server. The backup server will shutdown the CallXpress services on the System Server, take the system offline and begin to intercept messages between the Call Servers and the System Server (by taking on the IP address previously assigned to the System Server.) This allows the backup server to step in and take over for the System Server. Since it has an up-to-date copy of everything that was on the System Server, there is no loss of functionality.
Warm Standby Call Server… When CallXpress is configured and deployed, it is possible to add additional Call Servers to the system that are in a warm standby by mode. This is done by installing additional Call Servers and integrating them to the system but all ports are set to an inactive state. Now the standby Call Server is inactive (the ports are out of service) but the database on the system will be automatically updated by the replication from the System Server. In the event of a failure of one of the active Call Servers, the warm standby Call Server can be brought into service by simply putting the ports on the warm standby server into service. Since one of the Call Servers is offline (the failed server), the System Server will have port licenses available and allow the warm standby server to use those licenses to make the ports active. In most cases, the PBX will now see the ports as available will start routing calls to the new Call Server. When the problem is resolved on the failed Call Server, the administrator can take the ports out of service on the warm standby server and use the freed licenses to bring the restored regular Call Server online. The other option would be to make the newly repaired server the warm standby server and continue using the existing configuration.
Feature Name: Hot Standby System Server Dependencies:
Feature Description: As an option, CallXpress can be installed with an optional Hot Standby System
Server. This hot standby System Server contains an up-to-date copy of the full database from the active System Server. All changes made to the System Server are automatically replicated on the backup server. This includes program changes, software updates, user messages, recorded names, greetings and announcements, etc. The backup server also runs a program that is monitoring the health of the System Server. By monitoring certain critical functions and services, the backup server can tell the general health of the System Server. By monitoring certain critical functions and services, the backup server can tell the general health of the System Server. In the event that the backup server determines
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that the System Server is no longer functioning at a sufficient level, it takes steps to replace the System Server. The backup server will shutdown the CallXpress services on the System Server, take the system offline and begin to intercept messages between the Call Servers and the System Server (by taking on the IP address previously assigned to the System Server.) This allows the backup server to step in and take over for the System Server. Since it has an up-to-date copy of everything that was on the System Server, there is no loss of functionality.
Feature Name: RAID Technology Support Dependencies:
Feature Description: The CallXpress System Server, Hot Standby System Server and Call Servers all
support the use of support RAID storage. Redundant Array of Inexpensive Disks (RAID) is duplicated storage for the system, ensuring that the system data is secure. If a single disk of a RAID array fails, one or two others containing identical data are available to continue with uninterrupted service.
Feature Name: Warm Standby Call Server Option Dependencies:
Feature Description: CallXpress supports the ability to deploy multiple Call Servers in a single system. These Call Servers connect to the telephone system and handle all of the functions pertaining to answering and making calls. A system also can be configured with one or more warm standby Call Servers. A warm standby Call Server is a server that is fully loaded with CallXpress software and is equipped with the necessary integration hardware but is not actively answering calls and is not using any port licenses. The warm standby servers are, however, actively participating in the system database replication meaning that it always has a fully current version of the program and system database. In the event of the failure of one of the active Call Servers, an administrator can bring the warm standby Call Server on line and it will start handling the traffic that was previously handled by the Call Server that failed. Warm Standby Call Servers do not use any port licenses in their standby state, greatly reducing their cost.