3. 1. Basic Concepts Internet RMON Device Firewall / Router Management Station ... Polling Notification ... NM UNIX . . .. FDDI UNIX PC . . .. . . .. PC UNIX PC 8. SNMP Architectural Model ( cont. ) Manager Agent Agent . . . Management Station Host Router Network Elements (NEs) Network Management Protocol SNMP Network 網路介面 SNMP UDP IP 網路介面 SNMP UDP IP 網路介面 SNMP UDP IP 15. SNMP Services Get GetNext Set Trap Get Request Get Response Manager Agent GetNext Request Get Response Manager Agent Set Request Get Response Manager Agent Trap Request Manager Agent 17. Get-Next Request In SNMP, Only leaf objects have values. ＊ :Non-Leaf Object :Leaf Object 1 2 3 4 5 6 MIB Tree : 18. Default UDP Ports for SNMP 網路介面 SNMP UDP IP Manager Management Station Network Elements (NEs) 網路介面 SNMP UDP IP Agent 162 Any 161 Any 23. SMI (RFC1155) RFC1155-SMI DEFINITIONS ::= BEGIN EXPORTS -- EVERYTHING internet, directory, mgmt, experimental, private, enterprises, OBJECT-TYPE, ObjectName, ObjectSyntax, SimpleSyntax, ApplicationSyntax, NetworkAddress, IpAddress, Counter, Gauge, TimeTicks, Opaque; internet OBJECT IDENTIFIER ::= { iso org(3) dod(6) 1 } directory OBJECT IDENTIFIER ::= { internet 1 } mgmt OBJECT IDENTIFIER ::= { internet 2 } experimental OBJECT IDENTIFIER ::= { internet 3 } private OBJECT IDENTIFIER ::= { internet 4 } enterprises OBJECT IDENTIFIER ::= { private 1 } 24. SMI ( cont. ) OBJECT-TYPE MACRO ::= BEGIN TYPE NOTATION ::= "SYNTAX" type (TYPE ObjectSyntax) "ACCESS" Access "STATUS" Status VALUE NOTATION ::= value (VALUE ObjectName) Access ::= "read-only" | "read-write" | "write-only" | "not-accessible" Status ::= "mandatory" | "optional" | "obsolete" END ObjectName ::= OBJECT IDENTIFIER ASN.1 Macro 25. OBJECT-TYPE Example sysDesc OBJECT-TYPE SYNTAX DisplayString (SIZE (0..255)) ACCESS read-only STATUS mandary ::= { system 1} 26. ObjectName ::= OBJECT IDENTIFIER ObjectSyntax ::= CHOICE { simple SimpleSyntax, application-wide ApplicationSyntax} SimpleSyntax ::= CHOICE { number INTEGER, string OCTET STRING, object OBJECT IDENTIFIER, empty NULL} } ApplicationSyntax ::= CHOICE { address NetworkAddress, counter Counter, gauge Gauge, ticks TimeTicks, arbitrary Opaque } NetworkAddress ::= CHOICE { internet IpAddress} IpAddress ::= [APPLICATION 0] IMPLICIT OCTET STRING (SIZE (4)) Counter ::= [APPLICATION 1] IMPLICIT INTEGER (0..4294967295) Gauge ::= [APPLICATION 2] IMPLICIT INTEGER (0..4294967295) TimeTicks ::= [APPLICATION 3] IMPLICIT INTEGER (0..4294967295) Opaque ::= [APPLICATION 4] IMPLICIT OCTET STRING END SMI ( cont. ) 28. Concise MIB Definition (RFC 1212) OBJECT-TYPE MACRO ::= BEGIN TYPE NOTATION ::= "SYNTAX" type(ObjectSyntax) "ACCESS" Access "STATUS" Status DescrPart ReferPart IndexPart DefValPart VALUE NOTATION ::= value (VALUE ObjectName) DescrPart ::= "DESCRIPTION" value (description DisplayString) | empty ReferPart ::= "REFERENCE" value (reference DisplayString) | empty IndexPart ::= "INDEX" "{" IndexTypes "}" | empty IndexTypes ::= IndexType | IndexTypes "," IndexType IndexType ::= value (indexobject ObjectName) | type (indextype) DefValPart ::= "DEFVAL" "{" value (defvalue ObjectSyntax) "}" | empty END 29. Examples: MIB II (RFC 1213) ifEntry OBJECT-TYPE SYNTAX IfEntry ACCESS not-accessible STATUS mandatory DESCRIPTION "An interface entry containing objects at the subnetwork layer and below for a particular interface." INDEX { ifIndex } ::= { ifTable 1 } ifTable OBJECT-TYPE SYNTAX SEQUENCE OF IfEntry ACCESS not-accessible STATUS mandatory DESCRIPTION "A list of interface entries. The number of entries is given by the value of ifNumber." ::= { interfaces 2 } mib-2 OBJECT IDENTIFIER ::= { mgmt 1 } system OBJECT IDENTIFIER ::= { mib-2 1 } interfaces OBJECT IDENTIFIER ::= { mib-2 2 } at OBJECT IDENTIFIER ::= { mib-2 3 } ip OBJECT IDENTIFIER ::= { mib-2 4 } icmp OBJECT IDENTIFIER ::= { mib-2 5 } tcp OBJECT IDENTIFIER ::= { mib-2 6 } udp OBJECT IDENTIFIER ::= { mib-2 7 } egp OBJECT IDENTIFIER ::= { mib-2 8 } -- cmot OBJECT IDENTIFIER ::= { mib-2 9 } transmission OBJECT IDENTIFIER ::= { mib-2 10 } snmp OBJECT IDENTIFIER ::= { mib-2 11 } 32. Columnar Objects ifTable OBJECT-TYPE SYNTAX SEQUENCE OF IfEntry … ::= { interface 2 } IfEntry ::= SEQUENCE { ifIndex INTEGER, ifDescr DisplayString, ifType INTEGER, … } ifEntry OBJECT-TYPE SYNTAX IfEntry … INDEX {ifIndex } ::= { ifTable 1} ifDescr OBJECT-TYPE SYNTAX DisplayString (SIZE(0..255)) ACCESS read-only STATUS madatory ... ::= {ifEntry 2} 33. Columnar Objects ifIndex ifDescr ifType . . . 1 le0 6 . . . 6 llc0 1 . . . 7 lo0 24 . . . 9 le1 6 . . . .ifTable.ifEntry.1 (1.3.6.1.2.1.2.2.1. 1 ) .ifTable.ifEntry.2 (1.3.6.1.2.1.2.2.1. 2 ) .ifTable.ifEntry.3 (1.3.6.1.2.1.2.2.1. 3 ) 1.3.6.1.2.1.2.2.1.3.7 1.3.6.1.2.1.2.2.1.2. 6 42. SNMP PDU ( cont. ) PDU type request-id 0 0 variable-bindings GetRequest, GetNextRequest, SetRequest PDU type request-id error-status error-index variable-bindings GetResponse variable-bindings name value name value name value . . . 46. How does a Manager do? Translates Internal Data to ASN.1 Format Translates ASN.1 Package to Internal Data Format NM Application NM Application Agent Agent Manager Sends Request PDU to Agent Received Response PDU from Agent 47. How does an Agent do? From Manager To Manager Agent Received SNMP Request PDU from Manager Translates ASN.1 Structure to Internal Data Maps MIB Variables to Internal Variables Sends SNMP Response PDU to Manager Translates Response PDU to ASN.1 Format Implement SNMP Request to Set or Get MIB Value
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