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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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© 1999 BMC SOFTWARE, INC.2/11/00
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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© 1999 BMC SOFTWARE, INC.2/11/00
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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© 1999 BMC SOFTWARE, INC.2/11/00
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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© 1999 BMC SOFTWARE, INC.2/11/00
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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© 1999 BMC SOFTWARE, INC.2/11/00
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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© 1999 BMC SOFTWARE, INC.2/11/00
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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© 1999 BMC SOFTWARE, INC.2/11/00
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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© 1999 BMC SOFTWARE, INC.2/11/00
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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© 1999 BMC SOFTWARE, INC.2/11/00
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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© 1999 BMC SOFTWARE, INC.2/11/00
The SNMP Agent
What is an SNMP agent ? Components :
MIB (the MIB in memory) request handling trap sending
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© 1999 BMC SOFTWARE, INC.2/11/00
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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© 1999 BMC SOFTWARE, INC.2/11/00
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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© 1999 BMC SOFTWARE, INC.2/11/00
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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© 1999 BMC SOFTWARE, INC.2/11/00
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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© 1999 BMC SOFTWARE, INC.2/11/00
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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© 1999 BMC SOFTWARE, INC.2/11/00
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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© 1999 BMC SOFTWARE, INC.2/11/00
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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© 1999 BMC SOFTWARE, INC.2/11/00
The SNMP Manager
What is an SNMP manager ?
Components :present MIB info (display MIB files)send requests listen for traps