1. Yen-Cheng Chen http://ycchen.im.ncnu.edu.tw/ ycchen@ncnu.edu.tw
Introduction to SNMP
Yen-Cheng Chen

2. 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 .... Notification Polling .... .... Management
Station PC
UNIX NM
FDDI
...
....
RMON
Device
Polling
Notification
Firewall
/ Router
....
UNIX
....
... PC
Internet
UNIX PC

4. 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)。
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 ISO/ITU-T X.700 Series: ITU-T M.3000 Series:
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)

6. SNMP Concepts IAB: Internet Activities Board 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

7. 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.

8. SNMP Architectural Model (cont.)
Management
Station
Network Elements (NEs)
Host
Router
網路介面
SNMP
UDP IP
網路介面
SNMP
UDP IP
網路介面
SNMP
UDP IP
Manager
Agent
Agent
Network
Management
Protocol
. . .
SNMP
Network

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 monitor 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 unsolicited 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).

12. Management Information Base (MIB)
Managed Resources
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.
MIB
Agent
SNMP
UDP IP
網路介面
NE: Network Element

13. SNMP Services Four Services Five SNMP PDUs Manager Agent(s)
Get, Set, GetNext, Trap
Five SNMP PDUs
GetRequest, SetRequest, GetNextRequest, GetResponse, Trap
Get, Set, GetNext Request
Get Response
Trap
Manager
Agent(s)
PDU: Protocol Data Unit

14. SNMP Services Get GetNext Set Trap Manager Agent Manager Agent Manager
Get Request
Get Response
Manager
Agent
Get
GetNext
Set
Trap
GetNext Request
Get Response
Manager
Agent
Set Request
Get Response
Manager
Agent
Trap Request
Manager
Agent

15. SNMP Services (cont.) Get Request: Get-Next Request: Set 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.

16. Get-Next Request MIB Tree : 1 2 3 4 5 6 ＊ In SNMP,
Only leaf objects have
values.
:Non-Leaf Object
:Leaf Object

17. Default UDP Ports for SNMP
Management
Station
Network Elements (NEs)
Manager
Agent
SNMP
SNMP
162
Any
161
Any
UDP
UDP IP IP
網路介面
網路介面

18. 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.

19. 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, ...

20. Object Identifier Object Identifier (OID): 1.3.6.1.2.1 1.3.6.1.2.1.2
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 2 1
ccitt
iso
joint-iso-ccitt 3 2 1
std
reg
authority
org
member
body 6
dod 1
internet 1 4 2 3
directory
mgmt
experimental
private 1 1
MIB II
MIB II
enterprises
enterprises
system 1
interface 2
interface at 3 IP 4
ICMP 5
TCP 6
UDP 7
EGP 8
Trans. 10
SNMP 11

21. Private MIB Registration
Companies can register their private MIB extensions in the global MIB tree by contacting the Internet Assigned Numbers Authority (IANA).
Currently assigned enterprise subtrees
ftp://ftp.isi.edu/in-notes/iana/assignments/enterprise-numbers

22. 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 }

23. SMI (cont.) ASN.1 Macro 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

24. OBJECT-TYPE Example sysDesc OBJECT-TYPE
SYNTAX DisplayString (SIZE (0..255))
ACCESS read-only
STATUS mandary
::= { system 1}

25. SMI (cont.) ObjectName ::= OBJECT IDENTIFIER NetworkAddress ::=
ObjectSyntax ::=
CHOICE {
simple SimpleSyntax,
application-wide
ApplicationSyntax}
SimpleSyntax ::=
number INTEGER,
string OCTET STRING,
object OBJECT IDENTIFIER,
empty NULL} }
ApplicationSyntax ::=
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 ( )
Gauge ::=
[APPLICATION 2]
TimeTicks ::=
[APPLICATION 3]
Opaque ::=
[APPLICATION 4]
IMPLICIT OCTET STRING
END

26. Object Syntax Summary Simple Syntax Application Syntax Integer
Octet String
Object Identifier
Null
Application Syntax
Network Address
Counter
Gauge
Time Ticks
Opaque

27. Concise MIB Definition (RFC 1212)
DescrPart ::=
"DESCRIPTION" value (description DisplayString)
| empty
ReferPart ::=
"REFERENCE" value (reference DisplayString)
IndexPart ::=
"INDEX" "{" IndexTypes "}" | empty
IndexTypes ::=
IndexType | IndexTypes "," IndexType
IndexType ::=
value (indexobject ObjectName) | type (indextype)
DefValPart ::=
"DEFVAL" "{" value (defvalue ObjectSyntax) "}"
END
OBJECT-TYPE MACRO ::=
BEGIN
TYPE NOTATION ::=
"SYNTAX" type(ObjectSyntax)
"ACCESS" Access
"STATUS" Status
DescrPart
ReferPart
IndexPart
DefValPart
VALUE NOTATION ::=
value (VALUE ObjectName)

28. 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 }
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 }
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 }

29. 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

30. 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.2
mib-2.interface.ifTable.ifEntry.ifDescr.6
mib-2.interface.ifTable.ifEntry.ifType.2
mib-2.interface.ifTable.ifEntry.ifType.6

31. Columnar Objects IfEntry ::= SEQUENCE { ifTable OBJECT-TYPE
ifIndex INTEGER,
ifDescr DisplayString,
ifType INTEGER, … }
ifTable OBJECT-TYPE
SYNTAX SEQUENCE OF IfEntry …
::= { interface 2 }
ifEntry OBJECT-TYPE
SYNTAX IfEntry …
INDEX {ifIndex }
::= { ifTable 1}
ifDescr OBJECT-TYPE
SYNTAX DisplayString (SIZE(0..255))
ACCESS read-only
STATUS madatory
...
::= {ifEntry 2}

32. Columnar Objects
.ifTable.ifEntry.1 ( ) ifTable.ifEntry.2 ( )
.ifTable.ifEntry.3 ( )
ifIndex ifDescr ifType le
llc lo le

33. 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:
:1200 ===> :1600
 Use snmp_get_req. to get the “tcpConnState” of the tcpConnTable in MIB II.
tcpConnState ==>

35. MIB II System Group Interfaces Group Address-Translation 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.

36. MIB-II (cont.) TCP Group UDP Group EGP Group Transmission 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.

37. MIB-II MIB-II (RFC 1213) is superset of MIB-I
Objects that are related grouped into object groups
MIB module comprises module name, imports from other modules, and definitions of current module
RFC 1213 defines eleven groups

38. MIB II (RFC 1213)
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.

39. 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.
CMOT Group
Placeholder for OSI (CMIP Over TCP/IP)
Transmission Group
Provides details about the underlying transmission media for each interface.
SNMP Group
Provides the statistics of SNMP operations at the managed system.

41. System Group

42. System Group

43. 01000100 72= 8 + 64 sysServices OBJECT-TYPE SYNTAX INTEGER (0..127)
ACCESS read-only
STATUS mandatory
DESCRIPTION
"A value which indicates the set of services that
this entity primarily offers.
The value is a sum. This sum initially takes the
value zero, Then, for each layer, L, in the range
1 through 7, that this node performs transactions
for, 2 raised to (L - 1) is added to the sum. For
example, a node which performs primarily routing
functions would have a value of 4 (2^(3-1)). In
contrast, a node which is a host offering
application services would have a value of 72
(2^(4-1) + 2^(7-1)). Note that in the context of
the Internet suite of protocols, values should be
calculated accordingly:
layer functionality
1 physical (e.g., repeaters)
2 datalink/subnetwork (e.g., bridges)
3 internet (e.g., IP gateways)
4 end-to-end (e.g., IP hosts)
7 applications (e.g., mail relays)
For systems including OSI protocols, layers 5 and
6 may also be counted."
::= { system 7 }
72=

44. System Information

45. Interfaces Group

46. iFEntry

47. ifType

48. ifAdminStatus OBJECT-TYPE
SYNTAX INTEGER {
up(1), ready to pass packets
down(2),
testing(3) -- in some test mode }
ACCESS read-write
STATUS mandatory
DESCRIPTION
"The desired state of the interface. The testing(3) state indicates
that no operational packets can be passed."
::= { ifEntry 7 }
ifOperStatus OBJECT-TYPE
SYNTAX INTEGER {
up(1), ready to pass packets
down(2),
testing(3) -- in some test mode }
ACCESS read-only
STATUS mandatory
DESCRIPTION
"The current operational state of the interface. The testing(3)
state indicates that no operational packets can be passed."
::= { ifEntry 8 }

49. ifTable

50. ifTable (cont.)

52. IP Group

53. IP Group ipForwarding: IP Address Table contains table of IP addresses
not-forwarding(2)
IP Address Table contains table of IP addresses
IP Route Table contains an entry for each route
IP Network-to-Media Table is address translation table mapping IP addresses to physical addresses

54. IP Address Table

55. ipAddrTable

56. IP Routing Table

57. IP Routing Table

58. ipRouteTable Example Sec. other(1), invalid(2), direct(3), indirect(4)
local(2),
netmgmt(3),
icmp(4),
egp(5),
ggp(6),
hello(7),
rip(8),
is-is(9),
s-is(10),
ciscoIgrp(11),
bbnSpfIgp(12),
ospf(13),
bgp(14)

59. IP Address Translation Table

60. IP Address Translation Table

61. IPNetToMediaTable = ARP Table other(1), invalid(2), read-write
dynamic(3),
static(4)
read-write
= ARP Table

63. ICMP Group

64. ICMP icmpOutEchos icmpInEchoReps icmpInTimeExcs
Objects associated with ping
icmpOutEchos
- # ICMP echo messages sent
icmpInEchoReps
# ICMP echo reply messages received
Objects associated with traceroute/tracert
icmpInTimeExcs
# ICMP time exceeded messages received

65. TCP Group

66. TCP Connection Table

67. TCP Connection Table

68. TCP Connection State tcpConnState OBJECT-TYPE SYNTAX INTEGER {
closed(1),
listen(2),
synSent(3),
synReceived(4),
established(5),
finWait1(6),
finWait2(7),
closeWait(8),
lastAck(9),
closing(10),
timeWait(11),
deleteTCB(12) }
ACCESS read-write
STATUS mandatory …
::= { tcpConnEntry 1 }
TCP Connection State

69. tcpConnTable

71. UDP Group

72. UDP Group

73. udpTable

75. 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
.....

76. 3. SNMP Version SNMP PDU 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

77. SNMP Authentication Community Community Name Authentication Failure
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.

78. SNMP PDU Five SNMP PDUs: GetRquest : GetNextRequest : GetResponse :
PDU ::= 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 }
Five SNMP PDUs:
GetRquest :
GetNextRequest :
GetResponse :
SetRequest :
Trap :
[0] PDU
[1] PDU
[2] PDU
[3] PDU
[4] Trap-PDU
PDU: Protocol Data Unit

79. . . . SNMP PDU (cont.) PDU type request-id variable-bindings
variable-bindings
GetRequest, GetNextRequest, SetRequest
PDU type
request-id
error-status
error-index
variable-bindings
GetResponse
variable-bindings
name
value
. . .

80. Trap-PDU Enterprise: Agent Address: Generic Trap: Specific Trap:
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 and
the generation of the trap.
Variable Bindings
“Interesting” information
Trap-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 }
PDU type
enterprise
agent-addr
generic-trap
specific-trap
time-stamp
variable-bindings

81. How does a Manager do? Manager NM Application Agent NM Agent
Translates Internal
Data to
ASN.1 Format
Sends Request
PDU to Agent NM
Application
Agent
Translates ASN.1
Package to Internal
Data Format
Received Response
PDU from Agent NM
Application
Agent
Manager

82. How does an Agent do? Agent From Manager To Manager Received SNMP
Request PDU
from Manager
Translates ASN.1
Structure to
Internal Data
Maps MIB
Variables to
Internal Variables
From
Manager
Sends SNMP
Response PDU
to Manager
Translates Response
PDU to ASN.1
Format
Implement SNMP
Request to Set or
Get MIB Value To
Manager
Agent

83. 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.

84. 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.

85. What's New in SNMPv2 ... No more Trap PDU, 3 New PDUs: Added Security
getBulkReq, InformReq, SNMPv2-Trap
Added Security
18 Error Status Values
SNMPv2 SMI / SNMPv2 MIB
M-to-M Communications
Table Operations
...

86. 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]

87. Example for snmpget
>>snmpget -d Transmitted 41 bytes to camry ( ) port 161: Initial Timeout: 0.80 seconds 0: c a0 1a 02 0'.....public... 16: bc e 30 0c b : : 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: : 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: : NULL (0x5) 0 bytes

88. Example for snmpget (cont.)
Received 69 bytes from camry ( ) port 161: 0: c a C.....public.6. 16: bc a b *0(..+ 32: c e e 4d Sun SNM 48: e 74 2c e 57 2c 55 6c P Agent, SUNW,Ul 64: d tra : 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: : 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: : OCTET-STR (0x4) 28 bytes: "Sun SNMP Agent, SUNW,Ultra-1" system.sysDescr.0 : DISPLAY STRING- (ascii): Sun SNMP Agent, SUNW,Ultra-1

89. Example of snmpwalk snmpwalk 10.144.18.118 .1.3.6.1.2.1.1
system.sysDescr.0 : DISPLAY STRING- (ascii): Sun SNMP Agent, SUNW,Ultra-1
system.sysObjectID.0 : OBJECT IDENTIFIER: .iso.org.dod.internet.private.enterprises
system.sysUpTime.0 : Timeticks: ( ) 22 days, 22:36:39.58
system.sysContact.0 : DISPLAY STRING- (ascii):
system.sysName.0 : DISPLAY STRING- (ascii): camry
system.sysLocation.0 : DISPLAY STRING- (ascii): Information Technology Laboratory 3F
system.sysServices.0 : INTEGER: 72 ( )B

90. Example of snmptrap
snmptrap -d manager octetstringascii "Trap test"
Transmitted 64 bytes to manager ( ) port 162:
0: 30 3e c a >.....public.1.
16: 09 2b a
32: f C
48: 04 2b 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:
26: IPADDRESS AGENT-ADDR (0x40) 4 bytes: (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:
53: OCTET-STR (0x4) 9 bytes: "Trap test"

91. Get System Information
Get “System Group” of MIB II
Use get_request or get_next_request
sysDescr
sysObjectID
sysUptime
sysContact
sysName
sysLocation

92. Get Interface Information
Get “Interface Group” of MIB II
Repeatedly Use “get_next_request”
Note: We don’t know the ifIndex values in ifTable.
First get the next object of .ifTable.ifEntry.0
Then repeatedly “get_next”
Until the whole subtree is visited.

94. Traffic Monitoring (C2 - C1 )  8  100% (t2 - t1)  Bandwidth
Get “ifInOctets” and “ifOutOctets” of MIB II Interface Group
t1: C1 t2: C2
(C2 - C1 )  8
 100%
Utilization (%) =
(t2 - t1)  Bandwidth

96. 6. Reference The Simple Book, marshall T.Rose, Prentice-Hall Inc.
SNMP, SNMPv2 and RMON: The Practical Guide to Network Management, Willeam Stallings
SMI;
Concise MIB Format;
SNMP;
MIB II;
Trap Format;
ASN.1 and BER; ITU-T X.208, X.209

97. Development of SNMP Standards
SNMPv2  SNMPv3
RMON I
RMON II

98. 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)

99. RMON I & II