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

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

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 ?

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)

5 © 1999 BMC SOFTWARE, INC. 2/11/00 SNMP Syntax - SMI ASN.1 (iso “abstract notation one”)  SMI uses a subset of ASN.1  Well defined syntax for information exchange  comparable in functionality with XML

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)

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

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

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 SNMP v2C RFCs  SNMP v3 RFCs   

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

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)

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

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

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,...

15 © 1999 BMC SOFTWARE, INC. 2/11/00 NAMING in SNMP Naming hierarchy unique identifier, down to the instance of any object 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 enterpriseID peer BMC Company X Whatever you like

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

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

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

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

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

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