1. SNMPv2
These slides are based in parts upon slides of Prof. Dssouli (Concordia university)

2. Overview
SNMPv1 was developed as an interim solution to an eventual adoption of OSI.
This never came about: OSI was not as widely adopted as originally hoped.
SNMPv2, released in 1996, was basically major revisions added to SNMP.

3. SNMPv1 SNMPv1 Protocol SMIv1 Data Definition Language Full Standards:
RFC 1157 – Simple Network Management Protocol
SMIv1 Data Definition Language
Full Standards:
RFC Structure of Management Information
RFC Concise MIB Definitions
Informational:
RFC A Convention for Defining Traps
SMIv1 MIB Modules
RFC Management Information Base II
RFC Ethernet-Like Interface Types MIB

4. SNMPv2 SMIv2 Data Definition Language Full Standards:
RFC Structure of Management Information
RFC Textual Conventions
RFC Conformance Statements
SMIv2 MIB Modules
RFC Remote Network Monitoring MIB
RFC SNMP Framework MIB
RFC SNMPv3 MPD MIB
RFC SNMP Applications MIBs
RFC SNMPv3 USM MIB
RFC SNMP VACM MIB
RFC SNMP MIB

5. Major Changes Bulk data transfer
Request and receive bulk data using the get-bulk message
Manager-to-manager message
Enhances interoperability and allows for managing large distributed networks
Enhancements to SMI: SMIv2
Module definitions: MODULE-IDENTITY macro
Object definitions: OBJECT-TYPE macro (same as before)
Trap definitions: NOTIFICATION-TYPE macro
Textual conventions: define new data types
Conformance statements
Help customers compare features of various products
Keeps vendors open to their product’s compatibility with SNMP

6. Major Changes Row creation and deletion in table
A table can also be expanded by augmenting another table
MIB enhancements
Two new subgroups: security and snmpV2
Transport mappings
UDP remains the preferred transport protocol; however, other protocols can also be used with SNMPv2
Security features, originally to be in SNMPv2 moved to SNMPv3
SNMPv2 is community-based administrative framework
SNMPv2
mgmt
(2)
directory
(1)
experimental
(3)
private
(4)
Internet
{ }
security
(5)
snmpv2
(6)
SNMPv2 Internet Group

7. SNMPv2 System Architecture
SNMP Manager
Application
response
get-bulk-request
get-next-request
set-request
snmpV2-trap
SNMP
UDP IP
DLC
PHY
Physical Medium
PDU
get-request
inform-request
SNMP Agent

8. Additional Messages manager-to-manager message
inform-request
manager-to-manager message
The receiving manager responds with a response message
Enhances interoperability
get-bulk-request
transfer of large data, e.g. retrieval of table data
SNMPv2-trap
Similar to trap messages in SNMPv1

9. SMIv2- Modules Definitions
Defines and describe semantics of an information module (info. related to network management)
added to provide administrative information regarding the informational module and the revision history
MODULE-IDENTITY macro defines the module definitions

10. SMIv2- Object Definitions
OBJECT IDENTIFIER, OBJECT-IDENTITY, OBJECT-TYPE
OBJECT IDENTIFIER defines the administrative identification of a node in the MIB
OBJECT-IDENTITY macro (defines info. about OID) assigns an object identifier to a class of managed objects in the MIB (e.g., defining a class of routers!)
The object itself is not managed
OBJECT-TYPE macro defines the type of a managed object (e.g., a specific router type)
Focuses on the details of implementation
NOTE:
OBJECT-IDENTITY is high level description
OBJECT-TYPE details description needed for implementation

11. OBJECT-TYPE OBJECT-TYPE MACRO ::= BEGIN TYPE NOTATION ::=
"SYNTAX" Syntax
UnitsPart
"MAX-ACCESS" Access
"STATUS" Status
"DESCRIPTION" Text
ReferPart
IndexPart
DefValPart
VALUE NOTATION ::=
value(VALUE ObjectName)

12. "SYNTAX" Syntax Syntax ::= -- Must be one of the following:
-- a base type (or its refinement),
-- a textual convention (or its refinement), or
-- a BITS pseudo-type
type
| "BITS" "{" NamedBits "}“
NamedBits ::= NamedBit
| NamedBits "," NamedBit
NamedBit ::= identifier "(" number ")“
-- number is nonnegative

13. (Example) SYNTAX BITS protocolDirType OBJECT-TYPE SYNTAX BITS {
extensible(0),
addressRecognitionCapable(1) }
MAX-ACCESS read-only
STATUS current
DESCRIPTION “…”
::= { protocolDirEntry 5 }

14. UnitsPart: UNITS UnitsPart ::= "UNITS" Text | empty
hrDiskStorageCapacity OBJECT-TYPE
SYNTAX KBytes
UNITS "KBytes"
MAX-ACCESS read-only
STATUS current
DESCRIPTION "The total size for this long-term storage device. If the media is removable and is currently removed, this value should be zero."
::= { hrDiskStorageEntry 4 }
Back to OBJECT-TYPE

15. "MAX-ACCESS" Access Access ::= "not-accessible"
| "accessible-for-notify"
| "read-only"
| "read-write"
| "read-create"
ordered from least to greatest:
"not-accessible": indicates an auxiliary object
"accessible-for-notify": accessible only via a notification
"read-only": read only
"read-write": read and write, but create does not.
"read-create": read, write and create

16. "STATUS" Status “current”: the definition is current and valid.
| "deprecated"
| "obsolete"
“current”: the definition is current and valid.
“deprecated”: indicates an obsolete definition, it permits
new/continued implementation.
“obsolete”: the definition is obsolete and should not be
implemented.

17. ReferPart ReferPart ::= "REFERENCE" Text | empty
ipForwardTable OBJECT-TYPE
SYNTAX SEQUENCE OF IpForwardEntry
MAX-ACCESS not-accessible
STATUS obsolete
DESCRIPTION "This entity's IP Routing table."
REFERENCE "RFC 1213 Section 6.6, The IP Group“
::= { ipForward 2 }

18. Object Definitions, example
NOTE: A specific instance of routerIsi123 could be identified by its IP address

19. Table Definition Static Tables Dynamic Table
Tables completely controlled by the agent. Access is read-only, and read-write
These are useful when the number of rows corresponds to a fixed attribute (e.g., # physical interfaces) or a quantity controlled only by agent
Dynamic Table
Allows row creation/deletion by a manager
Access includes also read, write and create privileges
A table can be initialized with no rows and expanded as needed
SNMPv2: Augmentation of a table (dependent table)
Adds additional columns to an existing table (base table)
Number of rows is not affected
INDEX of the second table is the same as the first table
One to one correspondence between rows of two tables

20. Augmentation of Tables
Base table
Table 1
Augmented table
table1
table 2
(T1)
(T2)
table1Entry
table2Entry
(E1)
(E2)
T1.E1.C1.1
T1.E1.C2.1
T1.E1.C3.1
T2.E2.C4.1
T2.E2.C5.1
T1.E1.C1.2
T1.E1.C2.2
T1.E1.C3.2
T2.E2.C4.2
T2.E2.C5.2
T1.E1.C1.3
T1.E1.C2.3
T1.E1.C3.3
T2.E2.C4.3
T2.E2.C5.3
T1.E1.C1.4
T1.E1.C2.4
T.E1.C3.4
T2.E2.C4.4
T2.E2.C5.4
Example
Columnar object:T2.E2.C4
Index: T1.E1.C1.2
Value: T2.E2.C4.2
Conceptual rows:
1. T1.E1.C1.1
2. T1.E1.C1.2
3. T1.E1.C1.3
4. T1.E1.C1.4
Index:
First columnar object in Table 1

21. Augmentation of Tables
--Conceptual row extension
A clause used to increase the number of
columns in a table w/out rewriting the
table definition
Example: a vendor can easily specify vendor-specific objects as extensions to standard MIB table. It should be easier for applications to access these objects than if they were defined as new, separate table
The resulting table is therefore treated the same way
as if it was defined in a single table definition

22. Row Creation A new feature in SMIv2 2 methods
Create a row and make it active (or available)
Create a row and make it available at a later time
 definition of the status of a row
Used by agent to send responses to a manager
Used by manager for
row creation/deletion

23. 2 states for RowStatus: createAndGo, createAndWait
Row Creation
table1
entry1
status.1
index.1
data.1
status.2
index.2
data.2
status.3
index.3
data.3
Row to be created/deleted
2 states for RowStatus: createAndGo, createAndWait

24. Create and Go Manager initiates a SetRequest-PDU to create a new row
Agent
Managed
Process
Process
Entity
SetRequest (
status.3 = 4,
index.3 = 3,
data.3 = DefData )
Create Instance
Response (
status.3 = 1,
index.3 = 3,
data.3 = DefData )
Instance Created
Manager initiates a SetRequest-PDU to create a new row
status = 4, i.e., create and go
Agent interacts with the management entity and successfully create an instance; subsequently a response is transmitted to the manager
status = 1, indicates that the row is active

25. Create and Wait Manager Agent Process Process SetRequest (
status.3 = 5,
index.3 = 3 )
Create and wait, no default
data specified
Response (
status.3 = 3,
index.3 = 3 )
Agent responds with “notReady”
(no default value)
GetRequest (
data.3 )
Get the data for the row
Response (
data.3 = noSuchInstance)
Data value is missing
SetRequest (
data.3 = DefData )
Value of data is sent
Response (
status.3 = 2
Agent responds with
notInServcie
status.3 = 1 )
Manager requests to activate
the row
Row activated

26. Row Deletion SetRequest ( status.3 = 6 ) Response ( Manager Process
Agent
Managed
Entity
Delete Instance
Instance Deleted

27. Textual Conventions Enables defining new data types
Makes semantics of data types consistent and human readable
Creates new data types using existing ones and applies restrictions to them
An important textual convention in SNMPv2, RowStatus creates and deletes rows
SNMPv2
SNMPv1
A string of up to 255 characters
(refer to table 6.2 for more rules)

28. Textual Conventions-Macro
TEXTUAL-CONVENTION MACRO ::=
BEGIN
TYPE NOTATION ::=
DisplayPart
"STATUS" Status
"DESCRIPTION" Text
ReferPart
"SYNTAX" Syntax
VALUE NOTATION ::= value(VALUE Syntax)
DisplayPart ::= "DISPLAY-HINT" Text | empty
Status ::= "current" | "deprecated" | "obsolete“
ReferPart ::= "REFERENCE" Text | empty
………………………..
END
Example:
Hundredths ::= TEXTUAL-CONVENTION
DISPLAY-HINT “d-2”
...
SYNTAX INTEGER ( )
suggests that a Hundredths value of 1234 be rendered as "12.34"

29. Textual Conventions- example
RowStatus ::= TEXTUAL-CONVENTION
STATUS current
DESCRIPTION "The RowStatus textual convention is used to manage the …”
SYNTAX INTEGER {
-- the following two values are states:
-- these values may be read or written
active(1),
notInService(2),
-- the following value is a state:
-- this value may be read, but not written
notReady(3),
-- the following three values are
-- actions: these values may be written,
-- but are never read
createAndGo(4),
createAndWait(5),
destroy(6) }

30. SNMPv2 Protocol
Overall, 8 messages with almost common message format to improve the efficiency and performance
Significant improvement is that trap message has the same format
PDU
Error
Error
VarBind 1
VarBind 1
VarBind n
VarBind n
RequestID
...
Type
Status
Index
name
value
name
value
SNMPv2 PDU
Indicate the type of PDU
(e.g., Request-PDU, etc)
identifies the first variable binding
in the variable-binding list that
caused the error
Indicate the status of the error
(e.g., noError, tooBig, etc.)
NOTE:
SNMPv1 operations (e.g., GET-REQUEST) are atomic:
either all values are returned or none!
In SNMPv2: a binding list (with corresponding values) is prepared even if one variable cannot be returned  an (error-status), (error-index) are returned in the case of anomaly.

31. SNMPv2 Protocol
Error index is set to “0” if there is no error; otherwise, it identifies the first variable binding in the variable binding list that caused the error

32. SNMPv2 Protocol GetBulkRequest enables the retrieval of data in bulk
PDU
Non-
Max
VarBind 1
VarBind 1
VarBind n
VarBind n
RequestID
...
Type
Repeaters
Repetitions
name
value
name
value
SNMPv2 GetBulkRequest PDU
GetBulkRequest enables the retrieval of data in bulk
Uses the same selection principle as GetNexRequest (i.e., next object instance)
Retrieval of multiple rows of data from table (constrained by the max. message size)
Error status field replaced by Non-repeaters
Non-repeaters indicates the number of non repetitive (scalar) field values requested
Error index field replaced by Max repetitions
Max repetitions designates the maximum number of table rows requested to be returned in the response message
NOTE 1: value depends on the size of the SNMP message and buffer size in implementation
NOTE 2: no one to one relationship between the VarBindList of request and response messages

33. GetBulkRequest-PDU OperationZ A B
1.1 E
1.2
1.3
1.4
2.1
2.2
2.3
2.4
3.1
3.2
3.3
3.4
T.E.1.1
T.E.2.1
T.E.3.1
T.E.1.2
T.E.2.2
T.E.3.2 E T Z A B
T.E.1.3
T.E.2.3
T.E.3.3
T.E.1.4
T.E.2.4
T.E.3.4

34. GetBulkRequest-PDU Operation
GetRequest ( A,B )
GetNextRequest (T.E.1,T.E.2,T.E.3)
GetResponse (T.E.1.1,T.E.2.1,T.E.3.1)
GetNextRequest (T.E.1.1,T.E.2.1,T.E.3.1)
GetResponse (T.E.1.2,T.E.2.2,T.E.3.2)
GetResponse (T.E.1.3,T.E.2.3,T.E.3.3)
GetNextRequest (T.E.1.3,T.E.2.3,T.E.3.3)
GetResponse (T.E.1.4,T.E.2.4,T.E.3.4)
GetResponse (T.E.2.1,T.E.3.1,Z)
Manager
Process
Agent
GetResponse (A,B)
GetNextRequest (T.E.1.4,T.E.2.4,T.E.3.4)
GetNextRequest (T.E.1.2,T.E.2.2,T.E.3.2)

35. GetBulkRequest-PDU Operation
T.E.1.1
T.E.2.1
T.E.3.1
T.E.1.2
T.E.2.2
T.E.3.2 E T Z A B
T.E.1.3
T.E.2.3
T.E.3.3
T.E.1.4
T.E.2.4
T.E.3.4
2 non repetitive objects (A, B)
3 repetitive instances
Of the columnar object
T.E.1, T.E.2, T.E.3
Manager
Agent
Process
Process
GetBulkRequest ( 2,3,
A,B,T.E.1, T.E.2, T.E.3 )
Response ( A, B,
T.E.1.1, T.E.2.1, T.E.3.1
T.E.1.2, T.E.2.2, T.E.3.2
T.E.1.3, T.E.2.3, T.E.3.3 )
3 more rows
GetBulkRequest ( 0,3,
T.E.1.3, T.E.2.3, T.E.3.3 )
Response ( T.E.1.4, T.E.2.4, T.E.3.4, Z , "
endOfMibView" )
Z is next in the lexicographic order

36. GetBulkRequest-PDU Operation

37. SNMPv2 Trap PDU Addition of NOTIFICATION-TYPE macro
Error
Error
VarBind1
VarBind1
VarBind2
VarBind 2
RequestID
...
Type
Status
Index
sysUpTime
value
snmpTrapOID
value
Addition of NOTIFICATION-TYPE macro
Positions 1 and 2 in VarBindList are sysUpTime and snmpTrapOID
Inform-Request behaves as trap in that the message goes from one manager to another unsolicited
The receiving manager sends response to the sending manager

38. Conformance Statements for SMIv2 (RFC 2580)

39. MIB MODULE IMPORTS EXPORTS I MODULE-IDENTITY E TEXTUAL-CONVENTION MI
OBJECT IDENTIFIER
Application Data Types
OBJECT-TYPE
NOTIFICATION-TYPE
OBJECT-GROUP
NOTIFICATION-GROUP
MODULE-COMPLIANCE I E MI
TCs
OIs
OTs
NTs
OGs
NGs
MCs

40. data types I MI data types E MC MC OI OI TC TC NT NG OT OG OT OG NT NG

41. Four Macros in SNMPv2-CONF
OBJECT-GROUP macro
NOTIFICATION-GROUP macro
MODULE-COMPLIANCE macro
AGENT-CAPABILITIES macro

42. Conformance: OBJECT-GROUP
Conformance defined by
OBJECT-GROUP macro
NOTIFICATION-GROUP macro
OBJECT-GROUP
Compiled during implementation, not at run time
OBJECTS clause names each object
Every object belongs to an OBJECT-GROUP
Access defined by MAX-ACCESS, the maximum access privilege for the object

43. OBJECT-GROUP OBJECT-GROUP MACRO ::= BEGIN TYPE NOTATION ::=
ObjectsPart
"STATUS" Status
"DESCRIPTION" Text
ReferPart
VALUE NOTATION ::=
value(VALUE OBJECT IDENTIFIER)
ObjectsPart ::= "OBJECTS" "{" Objects "}"
Objects ::= Object | Objects "," Object
Object ::= value(ObjectName)
Status ::= "current" | "deprecated" | "obsolete"
ReferPart ::= "REFERENCE" Text | empty
Text ::= value(IA5String)
END

44. OBJECT-GROUP Example hrSWRunGroup OBJECT-GROUP OBJECTS {
hrSWOSIndex, hrSWRunIndex, hrSWRunName,
hrSWRunID, hrSWRunPath, hrSWRunParameters,
hrSWRunType, hrSWRunStatus }
STATUS current
DESCRIPTION
"The Host Resources Running Software Group."
::= { hrMIBGroups 4 }

45. Conformance: NOTIFICATION-GROUP
Contains trap entities defined in SMIv1
NOTIFICATIONS clause identifies the notifications in the group
NOTIFICATIONS-GROUP macro compiled during implementation, not at run time

46. NOTIFICATION-GROUP NOTIFICATION-GROUP MACRO ::= BEGIN
TYPE NOTATION ::=
NotificationsPart
"STATUS" Status
"DESCRIPTION" Text
ReferPart
VALUE NOTATION ::=
value(VALUE OBJECT IDENTIFIER)
NotificationsPart ::= "NOTIFICATIONS" "{" Notifications "}"
Notifications ::= Notification | Notifications "," Notification
Notification ::= value(NotificationName)
Status ::= "current" | "deprecated" | "obsolete"
ReferPart ::= "REFERENCE" Text | empty
Text ::= value(IA5String)
END

47. NOTIFICATION-GROUP Example
linkUpDownNotificationsGroup NOTIFICATION-GROUP
NOTIFICATIONS { linkUp, linkDown }
STATUS current
DESCRIPTION
"The notifications which indicate specific changes in the
value of ifOperStatus."
::= { ifGroups 14 }

48. Compliance Compliance has two classes of groups
MANDATORY-GROUPS ... Required
GROUP …Optional

49. MODULE-COMPLIANCE MODULE-COMPLIANCE MACRO ::= BEGIN TYPE NOTATION ::=
"STATUS" Status
"DESCRIPTION" Text
ReferPart
ModulePart
VALUE NOTATION ::=
value(VALUE OBJECT IDENTIFIER)

50. ModulePart ModulePart ::= Modules Modules ::= Module | Modules Module
"MODULE" ModuleName
MandatoryPart
CompliancePart
ModuleName ::= identifier ModuleIdentifier | empty
ModuleIdentifier ::= value(OBJECT IDENTIFIER) | empty
MandatoryPart ::= "MANDATORY-GROUPS" "{" Groups "}“ | empty
Groups ::= Group | Groups "," Group
Group ::= value(OBJECT IDENTIFIER)

51. CompliancePart (1/2) CompliancePart ::= Compliances | empty
Compliances ::= Compliance | Compliances Compliance
Compliance ::= ComplianceGroup | Object
ComplianceGroup ::=
"GROUP" value(OBJECT IDENTIFIER)
"DESCRIPTION" Text
Object ::=
"OBJECT" value(ObjectName)
SyntaxPart
WriteSyntaxPart
AccessPart

52. CompliancePart (2/2) SyntaxPart ::= "SYNTAX" Syntax | empty
-- must be a refinement for object's SYNTAX clause
WriteSyntaxPart ::= "WRITE-SYNTAX" Syntax | empty
Syntax ::= type | "BITS" "{" NamedBits "}"
NamedBits ::= NamedBit | NamedBits "," NamedBit
NamedBit ::= identifier "(" number ")"
AccessPart ::= "MIN-ACCESS" Access | empty
Access ::=
"not-accessible" | "accessible-for-notify"
| "read-only" | "read-write" | "read-create"

53. MODULE-COMPLIANCE Example
hrMIBCompliance MODULE-COMPLIANCE
STATUS current
DESCRIPTION
"The requirements for conformance to the Host Resources MIB."
MODULE -- this module
MANDATORY-GROUPS { hrSystemGroup, hrStorageGroup, hrDeviceGroup }
OBJECT hrSystemDate
MIN-ACCESS read-only
"Write access is not required.“
GROUP hrSWRunGroup
"The Running Software Group. Implementation of this group is mandatory
only when the hrSWRunPerfGroup is implemented." …
::= { hrMIBCompliances 1 }

54. OBJECT ifAdminStatus
SYNTAX INTEGER { up(1), down(2) }
MIN-ACCESS read-only
DESCRIPTION
"Write access is not required, nor is support for the value
testing(3)."

55. OBJECT-GROUP

56. Agent Capabilities AGENT-CAPABILITIES macro
SUPPORTS modules and includes groups
VARIATION identifies additional features

57. AGENT-CAPABILITIES

58. SNMPv2 Internet Group

59. NOTIFICATION-TYPE

60. Object Types for SNMPv2 Traps

61. Inform-Request
Inform-Request behaves as trap in that the message goes from one manager to another unsolicited
The receiving manager sends response to the sending manager

62. SNMPv2- Decentralized management
Agent
Element manager
MIB
SNMPv2
agent
MIB
SNMPv2
Manager/agent
Management server
MIB
Management Applications
SNMPv2
manager
MIB
SNMPv2
agent
MIB
SNMPv2
Manager/agent
MIB
SNMPv2
agent
SNMPv2 Configuration

63. Compatibility with SNMPv1
SNMPv2 MIB is not backward compatible with SNMPv1
Compatibility with SNMPv1  2 evolution paths:
Bilingual Manager
Proxy Server
Bilingual Manager expensive in resource and operation
SNMPv1
Agents
Bilingual Manager
Interpreter
SNMPv2
Agent
Profile
SNMP Bilingual Manager
Both interpreters are required!

64. SNMP Proxy Server SNMPv1 Agents SNMPv2 Manager Proxy Server SNMPv2
Pass-Through
SNMPv2 Manager
SNMPv1 Agent
GetNextRequest
GetRequest
SetRequest
Set: 1. non-repeaters = 0
2. max-repetitions = 0
GetBulkRequest
Exception: For 'tooBig' error, contents of variable-bindings
field removed .
Response
Prepend VarBind: 1. sysUpTime.0
2. snmpTrapOID.0
SNMPv2-Trap
GetResponse
Trap
SNMP v2-v1 Proxy Server

65. SNMPv2 MIB