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www.bmc.com 1 © 1999 BMC SOFTWARE, INC. 2/10/00 SNMP Simple Network Management Protocol
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2 © 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 u Maybe no (Free) Cpu u Maybe no (Free) Memory u Must be able to run everywhere u Real OS u Contained all intelligence u Made all decisions
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3 © 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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4 © 1999 BMC SOFTWARE, INC. 2/11/00 SNMP implementations Transport Transport protocol (UDP/IP) BER (iso 8825) - Basic Encoding Rules TLV (Type, Length, Value) encoding Versions SNMPv1 SNMPv2 SNMPv3 OSI network management implementation CMIP - CMOT ( used primarily in telephony along with SNMP)
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5 © 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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6 © 1999 BMC SOFTWARE, INC. 2/11/00 SNMPv3 New Draft Standard with enhanced Security User Based security model (rfc 2574) Administration Security (authentication, privacy and message integrity) View based access (VACM)
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7 © 1999 BMC SOFTWARE, INC. 2/11/00 RMON (Remote Network Monitoring) IETF rfc 1271 / rfc 1757 / rfc 1513 Physical Layer Management using probes (HW-SW) Extend SNMP functionality RMON MIB : contains RMON data Preventive Management : threshold based notification Statistics/History of data, Packet capturing, Host tables,… Operation modes Online Offline On Demand
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8 © 1999 BMC SOFTWARE, INC. 2/11/00 RMON2 Continued on RMON (rfc 2021) Statistics on network and upper layers All 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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9 © 1999 BMC SOFTWARE, INC. 2/11/00 SNMP References SNMP v1 RFCs 1155SMI 1157protocol 1212Concise MIB 1213MIB2 1215traps 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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10 © 1999 BMC SOFTWARE, INC. 2/11/00 UDP vs. TCP connection UDP RM Agents Console Agents TCP connectionless scalable not reliable connection oriented used to be non-scalable reliable
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11 © 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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12 © 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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13 © 1999 BMC SOFTWARE, INC. 2/11/00 Multiple SNMP Agents on 1 system Conflict : only 1 process can listen on a port Solutions : SMUX (SNMP Multiplexer) AgentX - Agent Extensibility (rfc 2741) Emanate (proprietary SNMP Research) 161 Master Agent Sub agent Application Device
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14 © 1999 BMC SOFTWARE, INC. 2/11/00 MIB (Management Information Base) The MIB definition textual description of MIB layout Written in SMI : Structure of Management Information SMI (the MIB definition language) Support for multiple datatypes Support for data definitions : indexed tables, structures, values,...
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15 © 1999 BMC SOFTWARE, INC. 2/11/00 NAMING in SNMP Naming hierarchy unique identifier, down to the instance of any object 1.3.6.1.4.1.1031 is the OID of the BMC Software subtree; Object identifier is the name iso 1 3 org 6dod 1 internet 2 mgmt 4 private 1enterprises 442 1031 enterpriseID peer BMC Company X Whatever you like
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16 © 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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17 © 1999 BMC SOFTWARE, INC. 2/11/00 Management Operations, SNMP requests and responses Get, Get Next, Set SNMPv1 responses are sent back Get Bulk (SNMPv2) Unsolicited Traps from Agent (v1) Informs (v2 and v3) - confirmed traps
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18 © 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 memory Performs operation if possible SNMP Agent sends response request ID OID value error status + index Similar for get-next operation returns next OID in tree
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19 © 1999 BMC SOFTWARE, INC. 2/11/00 Trap sending SNMP Agent sends 7 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 configured Patrol : /snmp/piV1m_list
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20 © 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
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21 © 1999 BMC SOFTWARE, INC. 2/11/00 Sending Requests Timebased polling User based requests Authentication : SNMPv1 : community names for r/w (most of the times, just private/public) SNMPv3 does it with MD5
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