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Practical VoIP Using VOCAL by Luan Dang, Cullen Jennings, David Kelly

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SNMP Daemon

There is a basic definition of the daemon near the beginning of the chapter; this section gives you a more complete definition. The SNMP daemon (SNMPd) is an agent that is located on every host within the system, providing local network management to any SNMP network management solution. The SNMPd can manage all VOCAL devices and many system processes. It also provides full SNMP v2 support including get, set, trap, and other message types, along with a simple proprietary UDP interface for colocated managed processes and an implementation for two-way registration with colocated managed processes.

High-Level Flow

On startup, the SNMPd sends out a hostwide multicast registration. It then monitors two User Datagram Protocol (UDP) ports for incoming messages and requests. The well-known SNMP port (161) receives requests from any network management station, and a VOCAL proprietary communication port (33604) processes registration and responses from the colocated managed processes.

The REGISTER message includes a UDP port for communication between the agent and the managed entity, the name of the process from the managed entity (RS1, for example), and the type of managed entity (RS, MS, FS, or SIP stack).

There can be multiple entities within a single process; for example, process RS1 has both an RS_Agent for Redirect server (RS)-specific information and a SIP_Agent for the Session Initiation Protocol (SIP) stack. The SNMPd correlates these entities and tracks their statuses. ...

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