Simple Network Management Protocol (SNMP)

 SNMP (Simple Network management protocol)

The SNMP enable a network device like router, switch, computer and hub to share information about itself and its activities. A complete SNMP consists of the following parts:

1.      SNMP Manager

A network management system that uses SNMP to poll and receive data from any number of network devices. It is usually is an application that runs in a central location.

2.       SNMP agent

A process that runs on the network device being monitored. All types of data are gathered by the device itself and stored in a local database. It responds to SNMP poll and queries with information from the database.

In network environment SNMP manager send a request to snmp agent and it accept the request on UDP 161 port, and again agent send ack to manager it use port no. 162.

 SNMP trap: News  of an event (interface state change, device failure, and so on) is sent without any ack that trap has been received.

 Inform request: New of an event is sent to an SNMP manager, and the manager is required to ack receipt by echoing the request back to the agent.

SNMP agent and managers data store in Management information base (MIB) database in memory.

MIB is tools which provide hierarchical virtual database of network objects describing a device being monitored by a network management system (NMS). It use by SNMP and remote monitoring 1 (RMON1).

Each and every MIB is based on the abstract syntax notation 1 (ASN 1) language.  Each variable in the MIB is referenced by an object identifier (OID).

SNMP version

1.       SNMPv1

2.       SNMPv2C

3.       SNMPv3

    Different between SNMP Version: 

     1. SNMPv1

            Authentication:   Community string

            Data Protection:   None

            Unique Feature : 32-bit counters

    2. SNMPv2c

          Authentication:   Community string

          Data Protection:  None

          Unique Feature:  adds bulk request and inform request message types, 64-bit counters

    3. SNMPv3

          Authentication:   Username

          Data Protection:  Hash-based MAC (SHA or MD5) DES, 3DES, AES(128-192,256 bit) encryption

          Unique Feature:  Adds user authentication, data integrity, and encryption adds restricted views