introduction to snmp
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Introduction to SNMP
Yen-Cheng Chen
http://www.im.ncnu.edu.tw/~ycchen/
ycchen@ncnu.edu.tw
Contents
1. Basic Concepts
2. Management Information Base
3. Simple Network Management Protocol
4. SNMP Application Examples
5. Reference
Appendix: ASN.1 Concept
3
1. Basic Concepts
InternetInternet
RMONDevice
UNIX....
FDDI
UNIX PC
Firewall/ Router
ManagementStation
ManagementStation
.......
PollingPolling NotificationNotification
....
...
PC UNIX
PC
NMNMNMNM
4
網路管理標準化
如果每個廠商的網路設備均提供一套獨特專屬 (Proprietary) 的網管方法與介面,網路管理工作將很難執行。
網路管理標準化 每個網路設備必須提供一致的網路管理介面
( 亦即相同的網路管理通信協定 ) 。
5
網路管理相關標準
Internet SNMPv1, SNMPv2, SNMPv3
ISO/ITU-T X.700 Series: CMIP/S (Common Management Information Protocol /
Service)
ITU-T M.3000 Series: TMN (Telecommunication Management Networks)
SNMP Concepts
SNMP: Simple Network Management Protocol De facto standards of network management for TCP/IP
networks (Internet) IAB recommends all IP & TCP implementations should
be network manageable. That is, all TCP/IP network devices should support
SNMP.
IAB: Internet Activities Board
SNMP Architectural Model
Key Components One or more Management Stations
• Perform management applications, i.e, Monitor & Control.
Multiple Network Elements• hosts, routers, gateways, ..., which each contain an Agent.
Network Management Protocol• Exchange network management information.
SNMP Architectural Model (cont.)
Network
網路介面
SNMP
UDP
IP
網路介面
SNMP
UDP
IP
網路介面
SNMP
UDP
IP
Manager Agent Agent
. . .
ManagementStation Host Router
Network Elements (NEs)
Network Management
Protocol
SNMP
9
Management Components
Manager Agent Network Management Protocol Management Information Base (MIB)
10
Management Components
Management Station (Manager) Network management applications. Provide an interface which the human network manager can m
onitor and control the network. Agent
Network devices should be equipped with agent software so that they can be managed from a management station.
Responds to requests for information from managers. Responds to requests for actions from managers. May asynchronously provide managers with important but uns
olicited information.
11
Management Components (cont.)
Network Management Protocol Communication protocol between managers and agents
NM protocol provides a standard way to exchange management information between managers and agents.
Management Information Base (MIB) A collection of Managed Objects.
The resources to be managed are represented as objects, called Managed Objects (MOs).
Management Information Base (MIB)
Each resource to be managed is represented by an object, called managed object (MO).
The MIB is a structured collection of MOs.
Essentially, each MO is a data variable.
Each agent in an NE maintains an MIB.
Monitor: by reading the values of MOs in the MIB.
Control: by modifying the values of MOs in the MIB.
網路介面
SNMP
UDP
IP
AgentAgent
Managed Resources
MIBMIB
NE: Network Element
SNMP Services Four Services
Get, Set, GetNext, Trap
Five SNMP PDUs GetRequest, SetRequest, GetNextRequest, GetResponse, Trap
Manager Agent(s)
Get, Set, GetNext Request
Get Response
Trap
PDU: Protocol Data Unit
14
SNMP Services
Get Request
Get ResponseManager Agent
GetNext Request
Get ResponseManager Agent
Set Request
Get ResponseManager Agent
Trap RequestManager Agent
Get
GetNext
Set
Trap
Get
GetNext
Set
Trap
SNMP Services (cont.)
Get Request: Retrieve the values of objects in the MIB of an agent.
Get-Next Request: Retrieve the values of the next objects in the MIB of an agent.
Set Request: Update the values of objects in the MIB of an agent.
Trap Request Report extraordinary events to the manager.
Get-Next Request
:Non-Leaf Object
:Leaf Object1 2 3
4 5 6
MIB Tree :In SNMP, Only leaf objects have values.
*
Default UDP Ports for SNMP
網路介面
SNMP
UDP
IP
Manager
ManagementStation
Network Elements (NEs)
網路介面
SNMP
UDP
IP
Agent
162 Any 161 Any
SNMP Standards
SNMP Protocol (Std 15) RFC1157: Simple Network Management Protocol.
Structure of Management Information (SMI) (Std 16) RFC1155: Structure and Identification of Management
Information for TCP/IP-based Internets. RFC1212: Concise MIB Definitions.
MIB-II (Std 17) RFC1213: Management Information Base for Network
Management of TCP/IP-based Internets: MIB-II.
http://www.isi.edu/rfc-editor/rfc.html
2. Management Information Base
Structure of Management Information (SMI) Set of rules on how managed objects should be defined. Objects are defined using Abstract Syntax Notation One ASN.1
(ITU-T X.208 / ISO 8824)
MIB The collection of all defined objects Contains hierarchically organized variables corresponding to
managed objects. MIB-II, RMON MIB, Bridge MIB, Repeater MIB, X.25 MIB,
FDDI MIB, Token Ring MIB, ...
Object Identifier Object Identifier (OID):
Global identifier for a particular object type. An OID consists of a sequence of integers, which specify the
position of the object in the global object identifier tree. root
ccitt iso joint-iso-ccitt
directory
0 1 2
std regauthority
memberbody
org0
1 2 3
dod
internet
6
1
12 3 4
mgmt experimental private
MIB II
system1
interface2
at3
IP4
ICMP5
TCP6
UDP7
EGP8
Trans.10
SNMP11
1 1enterprises
1.3.6.1.2.1.2 1.3.6.1.4.1
1.3.6.1.2.1
MIB II
interface
enterprises
21
Private MIB Registration
Companies can register their private MIB extensions in the global MIB tree by contacting the Internet Assigned Numbers Authority (IANA). http://www.iana.org/http://www.iana.org/
Currently assigned enterprise subtrees
ftp://ftp.isi.edu/in-notes/iana/assignments/enterprise-numbersftp://ftp.isi.edu/in-notes/iana/assignments/enterprise-numbers
SMI (RFC1155)RFC1155-SMI DEFINITIONS ::= BEGINEXPORTS -- 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 }
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
24
OBJECT-TYPE Example
sysDesc OBJECT-TYPE
SYNTAX DisplayString (SIZE (0..255))
ACCESS read-only
STATUS mandary
::= { system 1}
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.)
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Object Syntax Summary
Simple Syntax Integer Octet String Object Identifier Null
Application Syntax Network Address Counter Gauge Time Ticks Opaque
Concise MIB Definition (RFC 1212)
OBJECT-TYPE MACRO ::=BEGINTYPE NOTATION ::= "SYNTAX" type(ObjectSyntax) "ACCESS" Access "STATUS" Status
DescrPart ReferPart IndexPart DefValPartVALUE NOTATION ::=
value (VALUE ObjectName)
DescrPart ::="DESCRIPTION" value (description DisplayString)
| emptyReferPart ::=
"REFERENCE" value (reference DisplayString)| empty
IndexPart ::="INDEX" "{" IndexTypes "}" | empty
IndexTypes ::=IndexType | IndexTypes "," IndexType
IndexType ::=value (indexobject ObjectName) | type (indextype)
DefValPart ::="DEFVAL" "{" value (defvalue ObjectSyntax) "}"
| emptyEND
Examples: MIB II (RFC 1213)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 }
ifEntry OBJECT-TYPESYNTAX IfEntryACCESS not-accessibleSTATUS mandatoryDESCRIPTION
"An interface entry containing objects at the subnetwork layer and below for a particular interface."
INDEX { ifIndex }::= { ifTable 1 }
ifTable OBJECT-TYPESYNTAX SEQUENCE OF IfEntry
ACCESS not-accessibleSTATUS mandatory
DESCRIPTION"A list of interface entries. The number of entries is givenby the value of ifNumber."
::= { interfaces 2 }
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Identification of Managed Objects
Use Object Identifier (OID) OID = Object Type OID . Instance Identifier Object Type OID:
Each Object type has a unique OID
Instance Identifier: Identify instances of object type
E.g .mib-2.interface.ifTable.ifEntry.ifDescr.2
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Two Kinds of Managed Objects
Type-Specific Objects: sysDescr OBJECT-TYPE
SYNTAX DisplayString (SIZE(0..255))
::= {system 1}
OID: mib-2.system.1.0 Columnar Objects
OID:mib-2.interface.ifTable.ifEntry.ifDescr.2mib-2.interface.ifTable.ifEntry.ifDescr.6 mib-2.interface.ifTable.ifEntry.ifType.2mib-2.interface.ifTable.ifEntry.ifType.6
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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}
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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)
1.3.6.1.2.1.2.2.1.3.71.3.6.1.2.1.2.2.1.2.6
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Index in MIB II ifEntry {ifIndex} atEntry {atNetIfIndex, atNetAddress} ipAddrEntry {ipAdEntAddr } ipRouteEntry {ipRouteDest} ipNetToMediaEntry {ipNetToMediaIfIndex,
ipNetToMediaNetAddress} tcpConnEntry
{tcpConnLocalAddress, tcpConnLocalPort, tcpConnRemoteAddress, tcpConnRemotePort}
udpEntry {udpLocalAddress, udpLocalPort} egpNeighEntry {egpNeighAddr}
34
Index Example
To get the state of the TCP connection:10.144.18.118:1200 ===> 10.144.14.40:1600
Use snmp_get_req. to get the “tcpConnState” of the tcpConnTable in MIB II.
tcpConnState ==> .1.3.6.1.2.1.6.13.1.1
.1.3.6.1.2.1.6.13.1.1.10.144.18.118.1200.10.144.14.40.1600
MIB II System Group
Provide general information about the managed system. Interfaces Group
Contains generic information about the physical interfaces. Address-Translation Group
Contains information about the mapping between network addresses and physical addresses for each physical interface.
IP Group Contains information about the implementation and operation of IP at the
managed system. ICMP Group
Contains information about the implementation and operation of ICMP at the managed system.
MIB-II (cont.) TCP Group
Contains information about the implementation and operation of TCP at the managed system.
UDP Group Contains information about the implementation and operation of UDP at
the managed system. EGP Group
Contains information about the implementation and operation of EGP at the managed system.
Transmission Group Provides details about the underlying transmission media for each interface.
SNMP Group Provides the statistics of SNMP operations at the managed system.
IETF MIBs
1213 MIB-II 1316 Character Stream 1317 RS-232-like Hardware 1471 PPP 1513 RMON for Token Ring 1757 RMON 2021 RMON-II .....
3. SNMP SNMP Message
Version Identifier Community Name Protocol Data Unit
The length of SNMP messages should not exceed 484 octets.
Message ::= SEQUENCE {
version INTEGER {version-1(0)},community OCTET STRING,data ANY
}
Version Community SNMP PDU
SNMP Authentication
Community Relationship between an Agent and Managers.
Community Name Used to validate the SNMP messages. SNMP Password. Default ‘Get’ community name: “public”.
Authentication Failure Agent sends “Authentication Failure Trap” to
Manager.
SNMP PDUPDU ::= SEQUENCE {
request-id INTEGER,error-status INTEGER {
noError(0),tooBig(1),noSuchName(2),badValue(3),readOnly(4)genErr(5)},
error-index INTEGER,variable-bindings
SEQUENCE OF {name ObjectName,value
ObjectSyntax}
}
GetRquest :GetNextRequest :
GetResponse :SetRequest :
Trap :
[0] PDU[1] PDU[2] PDU[3] PDU[4] Trap-PDU
Five SNMP PDUs:
PDU: Protocol Data Unit
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. . .
Trap-PDUTrap-PDU ::= [4]
IMPLICIT SEQUENCE {enterprise OBJECT IDENTIFIER,agent-addr NetworkAddress,
generic-trap INTEGER { coldStart(0), warmStart(1), linkDown(2), linkUp(3), authenticationFailure(4), egpNeighborLoss(5), enterpriseSpecific(6)},
specific-trap INTEGER,time-stamp TimeTicks,variable-bindings VarBindList
}
Enterprise: Type of Object generating trap.
Agent Address:Address of object generating trap.
Generic Trap:Generic trap type.
Specific Trap:Enterprise specific trap.
Time Stamp:Time elapsed between the last initialization of the network entity andthe generation of the trap.
Variable Bindings“Interesting” information
PDU type enterprise agent-addr generic-trap variable-bindingsspecific-traptime-stamp
How does a Manager do?
Translates Internal Data to
ASN.1 Format
Sends RequestPDU to Agent
Translates ASN.1 Package to Internal
Data Format
Received ResponsePDU from Agent
NMApplication
NMApplication
Agent
Agent
Manager
How does an Agent do?
Received SNMP Request PDU from Manager
Translates ASN.1Structure to
Internal Data
Maps MIB Variables to
Internal Variables
Sends SNMP Response PDU
to Manager
Translates ResponsePDU to ASN.1
Format
Implement SNMP Request to Set orGet MIB Value
From Manager
To Manager
Agent
Main Loop of Agent Agent waits for an incoming datagram in Port 161 Reads the datagram from UDP and notes the transport
address of the sending entity. Increments the QUANTUM to keep track of the logical
request-id being processed by agent De-serializes the datagram into an ASN.1 structure. If
error occurs, log error and discard packet. The ASN.1 structure is translated into SNMP message. If
error occurs, log error and discard packet. Check on VERSION-NUMBER field. If error occurs, log
error and discard packet.
Main Loop of Agent (cont.) Community name is looked up.
If community is unknown to agent, agent send AUTHENTICATION trap to Manager station in Port 162; log error and discard packet.
Agent loops through list of variables in the request.
If no prototype is found, return a GET-RESPONE with error noSuchName and discard package.
Once prototype is fund, operation is checked against community profile. If mismatch occurs, return get-respone with error noSuchName or readOnly and discard package.
Otherwise, agent invokes access routine to perform the desired operation.
What's New in SNMPv2
No more Trap PDU, 3 New PDUs: getBulkReq, InformReq, SNMPv2-Trap
Added Security 18 Error Status Values SNMPv2 SMI / SNMPv2 MIB M-to-M Communications Table Operations ...
4. SNMP Application Examples SNMP Commands
snmpget [options] node variable [...]• query a node using SNMP Get request
snmpnext [options] node variable [...]• query a node using SNMP GetNext request
snmpwalk [options] node variable • query a node repeatedly using SNMP GetNext/GetBulk requests
snmptrap [-d] [-p port] [-c community] node enterprise agent-addr generic-trap specific-trap time-stamp variable type value [variable type value...]
• issue an SNMP Version 1 Trap options:[-d] [-t timeout] [-r retries] [-p port] [-c community] [-v version]
Example for snmpget>>snmpget -d 10.144.18.118 .1.3.6.1.2.1.1.1.0Transmitted 41 bytes to camry (10.144.18.118) port 161:Initial Timeout: 0.80 seconds 0: 30 27 02 01 00 04 06 70 75 62 6c 69 63 a0 1a 02 0'.....public... 16: 02 18 bc 02 01 00 02 01 00 30 0e 30 0c 06 08 2b .........0.0...+ 32: 06 01 02 01 01 01 00 05 00 -- -- -- -- -- -- -- ................ 0: SNMP MESSAGE (0x30): 39 bytes 2: INTEGER VERSION (0x2) 1 bytes: 0 (SNMPv1) 5: OCTET-STR COMMUNITY (0x4) 6 bytes: "public" 13: GET-REQUEST-PDU (0xa0): 26 bytes 15: INTEGER REQUEST-ID (0x2) 2 bytes: 6332 19: INTEGER ERROR-STATUS (0x2) 1 bytes: noError(0) 22: INTEGER ERROR-INDEX (0x2) 1 bytes: 0 25: SEQUENCE VARBIND-LIST (0x30): 14 bytes 27: SEQUENCE VARBIND (0x30): 12 bytes 29: OBJ-ID (0x6) 8 bytes: .1.3.6.1.2.1.1.1.0 39: NULL (0x5) 0 bytes
Example for snmpget (cont.)Received 69 bytes from camry (10.144.18.118) port 161: 0: 30 43 02 01 00 04 06 70 75 62 6c 69 63 a2 36 02 0C.....public.6. 16: 02 18 bc 02 01 00 02 01 00 30 2a 30 28 06 08 2b .........0*0(..+ 32: 06 01 02 01 01 01 00 04 1c 53 75 6e 20 53 4e 4d .........Sun SNM 48: 50 20 41 67 65 6e 74 2c 20 53 55 4e 57 2c 55 6c P Agent, SUNW,Ul 64: 74 72 61 2d 31 -- -- -- -- -- -- -- -- -- -- -- tra-1........... 0: SNMP MESSAGE (0x30): 67 bytes 2: INTEGER VERSION (0x2) 1 bytes: 0 (SNMPv1) 5: OCTET-STR COMMUNITY (0x4) 6 bytes: "public" 13: RESPONSE-PDU (0xa2): 54 bytes 15: INTEGER REQUEST-ID (0x2) 2 bytes: 6332 19: INTEGER ERROR-STATUS (0x2) 1 bytes: noError(0) 22: INTEGER ERROR-INDEX (0x2) 1 bytes: 0 25: SEQUENCE VARBIND-LIST (0x30): 42 bytes 27: SEQUENCE VARBIND (0x30): 40 bytes 29: OBJ-ID (0x6) 8 bytes: .1.3.6.1.2.1.1.1.0 39: OCTET-STR (0x4) 28 bytes: "Sun SNMP Agent, SUNW,Ultra-1"system.sysDescr.0 : DISPLAY STRING- (ascii): Sun SNMP Agent, SUNW,Ultra-1
Example of snmpwalk
snmpwalk 10.144.18.118 .1.3.6.1.2.1.1system.sysDescr.0 : DISPLAY STRING- (ascii): Sun SNMP Agent, SUNW,Ultra-1
system.sysObjectID.0 : OBJECT IDENTIFIER: .iso.org.dod.internet.private.enterprises.42.2.1.1
system.sysUpTime.0 : Timeticks: (198219958) 22 days, 22:36:39.58
system.sysContact.0 : DISPLAY STRING- (ascii): lino@ms.chttl.com.tw
system.sysName.0 : DISPLAY STRING- (ascii): camry
system.sysLocation.0 : DISPLAY STRING- (ascii): Information Technology Laboratory 3F
system.sysServices.0 : INTEGER: 72 (01001000)B
Example of snmptrap snmptrap -d manager .1.3.6.1.4.1.612.1.1 10.144.18.116 6 99999 0
.1.3.6.1.1 octetstringascii "Trap test"Transmitted 64 bytes to manager (10.144.18.100) port 162: 0: 30 3e 02 01 00 04 06 70 75 62 6c 69 63 a4 31 06 0>.....public.1. 16: 09 2b 06 01 04 01 84 64 01 01 40 04 0a 90 12 74 .+.....d..@....t 32: 02 01 06 02 03 01 86 9f 43 01 00 30 13 30 11 06 ........C..0.0.. 48: 04 2b 06 01 01 04 09 54 72 61 70 20 74 65 73 74 .+.....Trap test 0: SNMP MESSAGE (0x30): 62 bytes 2: INTEGER VERSION (0x2) 1 bytes: 0 (SNMPv1) 5: OCTET-STR COMMUNITY (0x4) 6 bytes: "public" 13: V1-TRAP-PDU (0xa4): 49 bytes 15: OBJ-ID ENTERPRISE (0x6) 9 bytes: .1.3.6.1.4.1.612.1.1 26: IPADDRESS AGENT-ADDR (0x40) 4 bytes: 10.144.18.116 (manager2) 32: INTEGER GENERIC-TRAP (0x2) 1 bytes: 6 35: INTEGER SPECIFIC-TRAP (0x2) 3 bytes: 99999 40: TIMETICKS TIME-STAMP (0x43) 1 bytes: 0 (0x0) 43: SEQUENCE VARBIND-LIST (0x30): 19 bytes 45: SEQUENCE VARBIND (0x30): 17 bytes 47: OBJ-ID (0x6) 4 bytes: .1.3.6.1.1 53: OCTET-STR (0x4) 9 bytes: "Trap test"
53
Get System Information
Get “System Group” of MIB II Use get_request or get_next_request
sysDescr .1.3.6.1.2.1.1.1.0
sysObjectID .1.3.6.1.2.1.1.2.0
sysUptime .1.3.6.1.2.1.1.3.0
sysContact .1.3.6.1.2.1.1.4.0
sysName .1.3.6.1.2.1.1.5.0
sysLocation .1.3.6.1.2.1.1.6.0
54
Get Interface Information
Get “Interface Group” of MIB II Repeatedly Use “get_next_request” Note: We don’t know the ifIndex values in i
fTable.First get the next object of .ifTable.ifEntry.0Then repeatedly “get_next”Until the whole subtree is visited.
55
56
Traffic Monitoring
Get “ifInOctets” and “ifOutOctets” of MIB II Interface Group
t1: C1 t2: C2
(C2 - C1 ) 8
(t2 - t1) Bandwidth 100%Utilization (%) =
57
6. Reference
The Simple Book, marshall T.Rose, Prentice-Hall Inc. SNMP, SNMPv2 and RMON: The Practical Guide to Network
Management, Willeam Stallings SMI; http://ds.internic.net/rfc/rfc1155.txt Concise MIB Format; http://ds.internic.net/rfc/rfc1212.txt SNMP; http://ds.internic.net/rfc/rfc1157.txt MIB II; http://ds.internic.net/rfc/rfc1213.txt Trap Format; http://ds.internic.net/rfc/rfc1215.txt ASN.1 and BER; ITU-T X.208, X.209
59
Development of SNMP Standards
SNMPv2 SNMPv3 RMON I RMON II
60
SNMPv3 An Architecture for Describing Internet Management
Frameworks Local Processing Model for version 3 of the Simple
Network Management Protocol (SNMPv3) Message Processing and Control Model for version 3 of
the Simple Network Management Protocol (SNMP) User-based Security Model for version 3 of the Simple
Network Management Protocol (SNMPv3) View-based Access Control Model (VACM) for version 3
of the Simple Network Management Protocol (SNMP) User-based Security Model (USM) for version 3 of the
Simple Network Management Protocol (SNMPv3)
61
RMON I & II
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