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    Network management systems use SNMP (Simple Network Management Protocol) to communicate with network elements.

    For this to work, the network element must be equipped with an SNMP agent.

    Most professional grade network hardware comes with an SNMP agent built in. These agents must be enabled and configured to communicate with the network management system.

    Operating systems such as Unix and Windows can also be configured with SNMP agents.

    SNMP Messages

    Either the network management system (NMS) or the network element intitiates SNMP messages.

    An SNMP TRAP is a message that a network element initiates and sends to the network management system. For example, a router can send a message if one of its redundant power supplies fails or a printer can send an SNMP trap when it is out of paper.

    An SNMP GET is a message that the network management system initiates when it wants to retrieve some data from a network element. For example, the network management system might query a router for the utilization on a WAN link every 5 minutes. It can then create charts and graphs from that data or warn the operator when the link is over utilized.

    An SNMP SET is a message that the NMS initiates when it wants to change data on a network element. For example, the NMS may wish to alter a static route on a router.

    The SNMP MIB

    The SNMP MIB (Management Information Base) is a collection of variables that are shared between the NMS and the network element (NE).

    The MIB is extensible, which means that hardware and software manufacturers can add new variables to it. These new MIB definitions must be added both to the network element and to the network management system.

    SNMP Community Strings

    The most basic form of SNMP security is the Community String.

    SNMP Community Strings are like passwords for network elements.

    There is often one community string used for read only access to a network element. The default value for this community string is often “public.” Using this community string like a password, the NMS can retrieve data from network elements.

    Less often, there is also a read-write community string. The default value for this is often “private.” Using this community string, the NMS can actually change MIB variables on a network element.

    SNMP Versions

    The SNMP protocol has benefited from major upgrades since its introduction in 1988.

    Unfortunately, a large percentage of network element vendors and even some network management system vendors are not taking advantage of these improvements.

    Many network elements support only SNMPv1 and SNMPv2c. Support for SNMPv3 is minimal.

    Version Description
    SNMPv1 SNMPv1, which implements community-based security
    SNMPv2c SNMPv2 with community-based security
    SNMPv2u SNMPv2 with user-based security
    SNMPv2 SNMPv2 with party-based security
    SNMPv3 SNMPv3, which implements user-based security

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    15 comments
    1. Sachin

      10 April, 2012 at 11:56 am

      It Would be good if added with more details on SNMP like how it manages the networks using MIB VAriables,and also want more details on MIB.

      Reply
    2. Rajesh

      27 March, 2012 at 5:25 am

      god may bless u with everhappines.
      Really very very very lucid.

      thanks u a lot

      Reply
    3. Jayashree

      14 March, 2012 at 6:34 am

      Nice article & very helfpul to understand basics

      Reply
    4. Shreeharsha N S

      7 November, 2011 at 4:22 am

      The best SNMP tool is HP OPEN VIEW.Any comments?

      Reply
      • JMon

        31 January, 2012 at 11:06 am

        Depends what you mean by SNMP tool…
        If you mean Network Management tool, then no you are wrong. IBM Tivoli Netcool is the best Network Management tool by a long long way.
        HP OpenView is OK for IT networks but cannot compete with IBM Tivoli Netcool when it comes to communications network management. Overall, IBM Tivoli Netcool is hands down the winner.

        Reply
    5. Thangam

      30 August, 2011 at 9:16 am

      It Would be good if added with more details on SNMP like how it manages the networks using MIB VAriables,and also want more details on MIB.

      Reply
    6. Indika

      18 August, 2011 at 5:41 am

      Nice and clear.. Thanks

      Reply
    7. Ejat

      27 July, 2011 at 7:28 am

      thank..really helpful for computer maintenance..
      n maybe programmer..

      Reply
    8. Senthil

      18 May, 2011 at 12:23 pm

      Nice one.
      Now im very clear about the concepts.

      Reply
    9. Rajni Bharti

      25 April, 2011 at 11:30 pm

      thanks 4 the SNMP version

      Reply
    10. nilesh

      6 April, 2011 at 2:03 pm

      thanks for this wonderful article it really helped me a  lot…….

      Reply
    11. saranya

      27 March, 2011 at 1:42 am

      thank u…really interesting

      Reply
    12. Evil-Thinker

      16 February, 2011 at 11:31 pm

      Really , i Found This Article Helpfull and Great , Before Reading it , i was Disturbed ..
      Now understand More Things and Articles i read Talked about Networks Security ,
      Thanks for Posting .

      Reply
    13. JakyMix

      24 January, 2011 at 8:12 pm

      I’ve been googling left to right trying to understand the concept behind SNMP. But this article made my life easier and now i’m quiet clear how it works and what it does. Thank you so much.

      Reply
      • Sesh

        9 February, 2011 at 6:43 am

        Nice aritcle on SNMP.
        i worked on SNMP but not clear on basic concepts. This article helped me..

        Reply
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