The Structure of Management Information (SMI) Naming OIDs, Defining OIDs SNMP Operations Hamdamboy Urunov, a Ph.D. Researcher student. Special Communication Research Center., Kookmin University Seoul, South Korea

Content Structure of Management Information (SMI) Managed Information Base (MIB ) Management Object (Object & Instance) SNMP configuration 2

Structure of Management Information - SMI 3 DIFFICULT TO UNDERSTAND - SMI? To make the definition of (new) MIBs easier The SMI helps MIB designers The SMI defines the syntax  The SMI allows tools to be build Question ?! For what is the SMI being used? What is the purpose of the SMI? SMIv1: RFC 1155 RFC 1212: concise MIB Definitions extends SMIv1 SMIv2: RFC 2578 RFC 2579: Textual Conventions definition of new types Answer !

4 Why is the SMI discussed in this presentation? not to learn you how to write large MIBs but to learn you how to READ MIBs Understand MIB definitions from internet – drafts and RFCs Structure of Management Information – SMI (0) How information in system? How defined management information system?

5 Structure of Management Information – SMI (1) 1.How Management information, which is stored within a system, may look like 2. How management information which is transported between systems may look like

6 Structure of Management Information – SMI (2) Management information within managed systems must be represented as: TABLES =two dimensional arrays of scalars SCALARS OF type Integer, Character, … Like “current time” “Number of packets received from system current time” Two dimensional arrays of scalars Create a structure of scalars the SNMP protocol can only exchange (a list of) scalars defined in terms of ASN.1 constructs

7 Structure of Management Information – SMI (2-1) For instance:

8 Structure of Management Information – SMI (2-2)

9 One can not READ/WRITE table with 1 operation to GET a table, one should READ each individual element this is complex Structure of Management Information – SMI (3) How to exchange managed information? Answer!!

10 Structure of Management Information – SMI (4)

11 Structure of Management Information – SMI (5)

12 Structure of Management Information – SMI (6)

SMI: Data type for scalars Counts from 0.. Max int can also count back (decrement) Compare to speed indicator Can not wrap This type is important speed of the car (machine)

14 SMI: Data type for scalars (cont..)

15 SMI: Data type for scalars (cont..)

16 Example of scalar objects

17 Example of scalar objects (cont…)

Object Naming 18 How can the manager identity, for example, the address, name AND uptime INTRODUCE a NAMING TREE THE LEAVES OF THE TREE REPRESENT THE MANAGED OBJECTSNODES ARE INTRODUCED FOR NAMING PURPOSES

19 Object Naming (CONT..) Object IS THE DEFINITION Instance has a value How about Scalar and Instance! In the case of scalars: Distinction between object and instance not useful In the case of tables : The object defines how rows look like There may be multiple INSTANCES of that OBJECT THUS there can be multiple rows The case of tables the distinction is useful

20 Object Naming (CONT..)

21 Object Naming (CONT..)

Object type definition 22

23 Object type definition - Example

24 Definition of non-leaf “Objects”

Definition of a MIB 25

Module Identity - Example 26

27 Module Identity – Example-1

Tables 28

Naming of Entries 29

30 Naming of Entries (cont…)

31 Naming of Entries (cont…)

Result 32 Difference between object and instance

Naming of table entries - Example 33

Table indexing – Index value 34

35 Table indexing – Index value

36 Table indexing – Index value

Table indexing – Multiple index field 37

38 Table indexing – Multiple index field

Table definition 39

40 Table definition

41 Table definition (cot…)

42 Table definition (cot…)

43 Definition of new types

44 Textual conventions

45 Row-status textual convention

Row-status - Example 46

Row-status – Example-1 47

48 Row-status – Example-2

Notification types 49

50 Notification types - 1

51 Notification types - 2

52 Notification types - 3

Object group constructor 53

A Standard For Managed Information 54

Naming OIDs 55 Managed objects Managed Objects are organized into a treelike hierarchy. This structure is the basis for SNMP’s naming scheme. An object ID An object ID is made up of a series of integers based on the nodes in the tree, separated by dots (.).

56 Naming OIDs (cont…) The first line declares internet as the OID , which is defined (the ::= is a definition operator) as a subtree of iso.org.dod, or The last four declarations are similar, but they define the other branches that belong to internet. For the directory branch, the notation { internet 1} tells us that it is part of the internet sub-tree and that its OID is The OID for mgmt is , and so on.

57 Naming OIDs (cont…) entreprises OBJECT IDENTIFIER ::= { private 1 }  There is currently one branch under the private subtree.  It’s used to give hardware and software ability to define their own private objects  for any type of hardware or software they want managed by SNMP.

58 Naming OIDs (cont…)  With your own enterprise number, you can create your own private MIB that allows you to monitor exactly what you want. Every object definition has the following format:

A Closer Look at MIB-II 59

60 SNMP Operations, the get Operation  How did the agent know what the NMS was looking for? One of the items in the get request is a variable binding.  A variable binding, or varbind, is a list of MIB objects that allows a request’s recipient to see what the originator wants to know.  Variable bindings can be thought of as OID=value pairs that make it easy for the originator (the NMS, in this case) to pick out the information  it needs when the recipient fills the request and sends back a response. $ snmpget -v 1 -c public cisco.ora.com system.sysLocation.0 = ""

Thank you 61