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WHAT IS SNMP?

SNMP means Simple Network MangamentProtocol

Simple Network Management Protocol

(SNMP) is used in network managementsystems to monitor network-attacheddevices.

It is used for monitoring status information

on a network. SNMP is used to monitor any device , provided

the device is SNMP capable These devices may include computers

,printers, routers , mainframes ,gateways etc.

http://en.wikipedia.org/wiki/Network_management_systemshttp://en.wikipedia.org/wiki/Network_management_systemshttp://en.wikipedia.org/wiki/Network_monitoringhttp://en.wikipedia.org/wiki/Network_monitoringhttp://en.wikipedia.org/wiki/Network_management_systemshttp://en.wikipedia.org/wiki/Network_management_systemshttp://en.wikipedia.org/wiki/Network_management_systemshttp://en.wikipedia.org/wiki/Network_monitoringhttp://en.wikipedia.org/wiki/Network_monitoringhttp://en.wikipedia.org/wiki/Network_management_systemshttp://en.wikipedia.org/wiki/Network_management_systemshttp://en.wikipedia.org/wiki/Network_management_systems

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BASIC COMPONENTS

OF SNMP

An SNMP-managed network consists of threekey component

Managed Device

Agents

Network Mangement Systems(NMS)

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Managed Device

A managed device is a network node thatcontains an SNMP agent and that resides on amanaged network.

Managed devices collect and storemanagement information and make thisinformation available to NMSs using SNMP.

Managed devices, sometimes called network

elements, can be any type of device including,but not limited to, routers, access servers,switches, bridges, hubs, IP telephones,computer hosts, and printers.

http://en.wikipedia.org/wiki/Routerhttp://en.wikipedia.org/wiki/Network_access_serverhttp://en.wikipedia.org/wiki/Network_switchhttp://en.wikipedia.org/wiki/Network_bridgehttp://en.wikipedia.org/wiki/Network_hubhttp://en.wikipedia.org/wiki/Routerhttp://en.wikipedia.org/wiki/IP_phonehttp://en.wikipedia.org/wiki/IP_phonehttp://en.wikipedia.org/wiki/IP_phonehttp://en.wikipedia.org/wiki/Network_access_serverhttp://en.wikipedia.org/wiki/Network_switchhttp://en.wikipedia.org/wiki/Host_(network)http://en.wikipedia.org/wiki/Network_bridgehttp://en.wikipedia.org/wiki/Network_hubhttp://en.wikipedia.org/wiki/Computer_printerhttp://en.wikipedia.org/wiki/Computer_printerhttp://en.wikipedia.org/wiki/Computer_printerhttp://en.wikipedia.org/wiki/IP_phonehttp://en.wikipedia.org/wiki/Host_(network)http://en.wikipedia.org/wiki/Computer_printerhttp://en.wikipedia.org/wiki/Computer_printerhttp://en.wikipedia.org/wiki/Host_(network)http://en.wikipedia.org/wiki/IP_phonehttp://en.wikipedia.org/wiki/Network_hubhttp://en.wikipedia.org/wiki/Network_bridgehttp://en.wikipedia.org/wiki/Network_switchhttp://en.wikipedia.org/wiki/Network_access_serverhttp://en.wikipedia.org/wiki/Router

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Agents

An agent is a network-management softwaremodule that resides in a managed device.

An agent has local knowledge of management

information and translates that informationinto a form compatible with SNMP.

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Network Management Systems

A network management system (NMS)executes applications that monitor andcontrol managed devices.

NMSs provide the bulk of the processing andmemory resources required for networkmanagement.

One or more NMSs may exist on any managednetwork.

http://en.wikipedia.org/wiki/Network_management_systemhttp://en.wikipedia.org/wiki/Network_management_system

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SNMPv1 and SMI

The SNMPv1 SMI (structure ofmanagementinformation) specifiesthe use of a number of SMI-specific

data types, which are divided into twocategories:

Simple data types

Application-wide data types

http://en.wikipedia.org/wiki/Structure_of_Management_Informationhttp://en.wikipedia.org/wiki/Structure_of_Management_Information

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Simple data types

Three simple data types are defined in theSNMPv1 SMI, all of which are uniquevalues:

The integer data type is a signed integer inthe range of -231 to 231-1.

Octet strings are ordered sequences of 0 to65,535 octets.

Object IDs come from the set of all objectidentifiers allocated according to the rulesspecified in ASN.1.

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Application-wide data types

Network addressesrepresent addresses from aparticular protocol family. SMIv1 supports only 32-bit(IPv4) addresses (SMIv2 uses Octet Strings torepresent addresses generically, and thus are usablein SMIv1 too. SMIv1 had an explicit IPv4 address

datatype.) Countersare non-negative integers that increase

until they reach a maximum value and then roll over tozero. SNMPv1 specifies a counter size of 32 bits.

Gauges are non-negative integers that can increase

or decrease between specified minimum and maximumvalues. Whenever the system property representedby the gauge is outside of that range, the value ofthe gauge itself will vary no further than therespective maximum or minimum, as specified in RFC

2578.

http://tools.ietf.org/html/rfc2578http://tools.ietf.org/html/rfc2578http://tools.ietf.org/html/rfc2578http://tools.ietf.org/html/rfc2578http://tools.ietf.org/html/rfc2578

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Time ticks represent time since some event,measured in hundredths of a second.

Opaques represent an arbitrary encoding that is usedto pass arbitrary information strings that do notconform to the strict data typing used by the SMI.

Integersrepresent signed integer-valuedinformation. This data type redefines the integerdata type, which has arbitrary precision in ASN.1 butbounded precision in the SMI.

Unsigned integers represent unsigned integer-valuedinformation, which is useful when values are alwaysnon-negative. This data type redefines the integerdata type, which has arbitrary precision in ASN.1 butbounded precision in the SMI.

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SNMPv2 and SMI

It makes certain additions and enhancements to theSNMPv1 SMI-specific data types, such as includingbit strings, network addresses, and counters.

Bit strings are defined only in SNMPv2 and comprise

zero or more named bits that specify a value. Network addresses represent an address from a

particular protocol family. Counters are non-negative integers that increase until

they reach a maximum value and then return to zero.In SNMPv1, a 32-bit counter size is specified. In SNMPv2, 32-bit and 64-bit counters are defined.

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SNMPv3

SNMPv3 primarily added security and remoteconfiguration enhancements to SNMP.

SNMPv3 is the current standard version of

SNMP as of 2004. It considers earlier versions to be obsolete

(designating them "Historic"). In December 1997 the "Simple Times"

newsletter published several articles writtenby the SNMPv3 RFC editors explaining someof the ideas behind version 3 specifications.

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SNMPv3 provides important security

features

Message integrity to ensure that a packethas not been tampered with in transit.

Authentication to verify that the message isfrom a valid source.

Encryption of packets to prevent snooping byan unauthorized source.

http://en.wikipedia.org/wiki/Data_integrityhttp://en.wikipedia.org/wiki/Authenticationhttp://en.wikipedia.org/wiki/Encryptionhttp://en.wikipedia.org/wiki/Encryptionhttp://en.wikipedia.org/wiki/Authenticationhttp://en.wikipedia.org/wiki/Data_integrity