L14
SNMP: manager, agent, MIB, OID and security
Cram this first — memory hook
161: ask one question. 162: receive two notification types, traps/informs. Management Information Base = menu; Object Identifier = item number.
Exam trap
Simple Network Management Protocol counters and Syslog event messages are different monitoring evidence; a trap is not a regularly scheduled poll.
The slide facts
monitors device health and interface statistics. A describes available values, an identifies a value, polling uses User Datagram Protocol 161 and traps go to 162. Version 3 supports authentication and encryption.
If you have time — extra
Simple Network Management Protocol () lets a manager collect information from agents on switches, routers and other devices. A Management Information Base () describes the managed objects; an Object Identifier () identifies an object in the naming hierarchy. Think menu and menu-item code. Polling asks for a value, such as interface traffic, at intervals. A trap is an unsolicited notification; an inform is a notification with an acknowledgment mechanism. The agent commonly listens on User Datagram Protocol () 161, while the notification receiver listens on 162. Version 2c commonly relies on community strings without encryption. Version 3 can provide authentication and privacy, but administrators must choose/configure the appropriate security level; version 3 alone does not guarantee encrypted messages. Limit which management systems may query devices and avoid exposing write access unnecessarily.
Walkthrough
Enable/configure the agent, choose suitable version/security settings, authorize the monitoring server, select useful objects to poll, configure the notification receiver, then verify both values and alerts.