Www.bmc.com 1 © 1999 BMC SOFTWARE, INC. 2/10/00 SNMP Simple Network Management Protocol

www.bmc.com

1© 1999 BMC SOFTWARE, INC.2/10/00

SNMPSimple Network Management Protocol

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© 1999 BMC SOFTWARE, INC.2/11/00

Why was SNMP invented ?

Designed to run on non-OS systems, later used in various ways for monitoring

No “BRAINS”

SNMP Agent

THE “BRAINS”

SNMP Manager

Maybe no (Free) Cpu Maybe no (Free) Memory Must be able to run everywhere

Real OS Contained all intelligence Made all decisions

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Protocol, its versions and extentions

What is SNMP About the protocol versions

SNMPv1, SNMPv2 ( c ) and SNMPv3

Some other things:RMON, RMON 2, SMI's and MIB's

SNMPv3 - as a future path for SNMP community ?

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SNMP implementations

TransportTransport protocol (UDP/IP)BER (iso 8825) - Basic Encoding Rules

TLV (Type, Length, Value) encoding

VersionsSNMPv1SNMPv2SNMPv3

OSI network management implementationCMIP - CMOT ( used primarily in telephony along with

SNMP)

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SNMP Syntax - SMI

ASN.1 (iso 8824 - “abstract notation one”)SMI uses a subset of ASN.1

Well defined syntax for information exchange

comparable in functionality with XML

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SNMPv3

New Draft Standard with enhanced SecurityUser Based security model (rfc 2574)

Administration

Security (authentication, privacy and message integrity)

View based access (VACM)

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RMON (Remote Network Monitoring)

IETF rfc 1271 / rfc 1757 / rfc 1513Physical Layer Management using probes (HW-SW)Extend SNMP functionality

RMON MIB : contains RMON dataPreventive Management : threshold based notificationStatistics/History of data, Packet capturing, Host tables,…Operation modes

Online Offline On Demand

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RMON2

Continued on RMON (rfc 2021)Statistics on network and upper layersAll of the leading probe vendors support it

NetScout, Technically Elite, Solcom, HP, 3Com, Bay, Cisco, Cabletron

Difficult to use all features because of vendor specific implementations

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SNMP References

SNMP v1 RFCs 1155 SMI 1157 protocol 1212 Concise MIB 1213 MIB2 1215 traps

SNMP v2 RFCs historical

See also : The Simple Web http://snmp.cs.utwente.nl/

SNMP v2C RFCs 1902-1907

SNMP v3 RFCs 1905-1907 2571-2575 2578-2580

http://www.ietf.org

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UDP vs. TCP connection

UDP

RMRM

Agents

Console

Console

Agents

TCP• connectionless• scalable• not reliable

• connection oriented• used to be non-scalable• reliable

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SNMP : Underlying Transport

UDP/IP implications unreliable no confirmation or guarantee order uncertain may duplicate

unsecure No authentication on transport layer No verification of origin (message spoofing) No integrity (message can be tampered with)

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The SNMP Agent

What is an SNMP agent ? Components :

MIB (the MIB in memory) request handling trap sending

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Multiple SNMP Agents on 1 system

Conflict : only 1 process can listen on a portSolutions :SMUX (SNMP Multiplexer)AgentX - Agent Extensibility (rfc 2741)Emanate (proprietary SNMP Research)

161

MasterAgent

Sub agent

Sub agent

Sub agent

Application

Application

Device

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MIB (Management Information Base)

The MIB definition textual description of MIB layoutWritten in SMI : Structure of Management Information

SMI (the MIB definition language)Support for multiple datatypesSupport for data definitions : indexed tables, structures,

values,...

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NAMING in SNMP

Naming hierarchyunique identifier, down to the instance of any object1.3.6.1.4.1.1031 is the OID of the BMC Software subtree;Object identifier is the name

iso1

3 org

6 dod

1 internet

2mgmt

4private

1 enterprises

442 1031enterpriseID

peerBMC Company X

Whatever you like

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SNMP Management

Remote Management :

From a geographically separate location configure monitor control

a remote system application device OS

Management console

Mgmt info, i.e., interesting info

“application”

Managed system

Mgmt protocol

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Management Operations,SNMP requests and responses

Get, Get Next, SetSNMPv1 responses are sent back

Get Bulk (SNMPv2)

Unsolicited Traps from Agent (v1)

Informs (v2 and v3) - confirmed traps

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Request handling

SNMP Agent gets request from mgr listens on specific port : typically 161 receives request : request ID + OID

Lookup of OID in memoryPerforms operation if possibleSNMP Agent sends response

request ID OID value error status + index

Similar for get-next operation returns next OID in tree

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Trap sending

SNMP Agent sends7 predefined Generic trap types (0-6)

0-5 = Standard traps

6 = Enterprise Specific

Sends to port 162 (default) on trap receiving machine

Trap destinations has to be configuredPatrol : /snmp/piV1m_list

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The SNMP Manager

What is an SNMP manager ?

Components :present MIB info (display MIB files)send requests listen for traps

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Sending Requests

Timebased pollingUser based requests

Authentication :SNMPv1 : community names for r/w (most of the

times, just private/public)SNMPv3 does it with MD5

Documents

Www.bmc.com 1 © 1999 BMC SOFTWARE, INC. 2/10/00 SNMP Simple Network Management Protocol