SNMP uses a manager/agent model for managing the devices.
The agent resides in the device and provides the interface to the physical device being managed. The manager resides on the management system and provides the interface between the user and the SNMP agent. The interface between the SNMP manager and the SNMP agent uses a Management Information Base (MIB) and a small set of commands to exchange information.
The vRouter supports SNMP over both IPv4 and IPv6 networks.
- MIB objects—A MIB contains the set of variables and objects that are managed (for example, MTU on a network interface). The objects are organized into a tree structure in which each object is a leaf node. Each object has its unique Object Identifier (OID). Objects are of two types: scalar and tabular. A scalar object defines a single object instance. A tabular object defines multiple related object instances that are grouped in MIB tables. For example, the uptime on a device is a scalar object, but the routing table in a system is a tabular object.
- Traps—In addition to MIB objects, the SNMP agent on a device can formulate alarms and notifications into SNMP traps. The device asynchronously sends the traps to the SNMP managers that are configured as trap destinations or targets. This sending of traps keeps the network manager informed of the status and health of the device. Traps are unacknowledged by the remote application that receives the message. The vRouter uses User Datagram Protocol (UDP) for traps. For SNMP requests, UDP port 161 is used. For SNMP traps, UDP port 162 is used. SNMPv2 and SNMPv3 support traps. Traps can be configured for each routing protocol. Note: Protocols BFD, BGP, and OSPF are supported for SNMP traps and these traps are disabled by default.
- Informs— Informs are acknowledged traps. After receiving an inform notification, a remote application sends back an acknowledge message indicating that it received the message. By default, the vRouter uses UDP for inform notifications and sends inform notifications to trap targets. Note: SNMPv3 supports informs.