Alcatel OmniTouch ACS 7.1.4, Руководство по подготовке площадки

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Application servers Stack Design and Operation
A - 4 8AL90212USAC ed01
November 20, 2008
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Application servers
Application Servers host AMDS (Automated Message Delivery System), My Teamwork,
and other Alcatel-Lucent applications. They are responsible for all user-specific functions,
such as provisioning, scheduling conferences, authentication, etc. All calls and sessions
originate with a request generated by an Alcatel-Lucent application; even dial-in calls are
authenticated and routed in accordance with an application’s direction. Application
servers also provide some real-time coordination of call signaling. At any one time, each
stack has a single active Application Server which acts as a central control point for the
stack’s activities. Approximately 10,000 users may be provisioned on a single Application
Server. The stack may also contain several Media Servers.
Failover for Application servers is provided by designating another server in the stack as a
secondary Application Server. (The one which is currently enabled is designated as
primary .) The secondary server keeps a redundant database of all application data,
synchronized in near real-time with the primary via the Data Replication feature.
Application databases include provisioned users and their profiles, scheduled conferences,
session logs, call recordings, and shared documents. Data Replication maintains the
secondary Application Server in what is commonly called “hot standby” mode for the
primary . If the primary server ceases to function, the secondary automatically detects the
failure and takes over. When the primary becomes available again (My Teamwork servers
automatically restart when they encounter failure), it resumes its primary role.
If the primary was acting as a media server as well, any connections which were active on
the primary will drop. However, if there were conferences active which used media on
multiple servers, the conference will continue undisturbed; if members are dropped when
the
primary users dial-in again, they will be connected to another media server and rejoin
the conference.
If there are active IM sessions on an Application Server when it fails, these sessions will be
dropped. The session log up through the time of failure will be preserved.
Media servers
OmniTouch ACS Media Servers control the PSTN and IP/RTP connections that carry
voice data streams. They handle call control and signaling for voice, perform mixing of
audio streams, and report data on each call connection (leg) to Application Servers. They
are not aware of individual user identities; they deal with streams of data (media) – thus,
no state information or databases need to be exchanged between them to enable Media
Servers to serve as ‘hot standby’ for each other. Failover for Media Servers is provided in
the same way that failover is provided for individual media interfaces: if a PSTN line goes
down, calls active on that interface drop and it is simply not used again until its status