Transcript Simple Network Management Protocol

PRESENTATIONS IN NETWORK MANAGEMENT
SNMP: Simple Network
Management Protocol
Saad Haj Bakry, PhD, CEng, FIEE
Saad Haj Bakry, PhD, CEng, FIEE
1
SNMP: Simple Network Management Protocols
Objectives / Contents
 SNMP
Principles
 SNMP
Information Representation
 SNMP Operation
 Remarks
Saad Haj Bakry, PhD, CEng, FIEE
2
SNMP: Simple Network Management Protocols
SNMP Principles
Introduction
 Components
 Multi-Vendor Principles
 Information Flow
 Framework

Saad Haj Bakry, PhD, CEng, FIEE
3
SNMP: Simple Network Management Protocols
Introduction to SNMP

For TCP/IP Networks:
– Internet / Extranet /Intranet
(multi-vendor distributed networks)

First issued in 1989
– Developed by IEFT (Internet Research Task Force)
Subsidiary of IAB (Internet Architecture Board)
– Supported by 70 vendors


SNMPv3: 1998
Widely implemented / with (+)
Saad Haj Bakry, PhD, CEng, FIEE
4
SNMP: Simple Network Management Protocols
SNMP Components
A Computer Running Management Software (with GUI)
Host
SNMP
Management
Station
Agent
Managed
Node
Management
LAN
Managed
Node
Printer
Process
Bridge Agent
Router
Saad Haj Bakry, PhD, CEng, FIEE
Agent
Agent
Managed
Node
Managed
Node
5
SNMP: Simple Network Management Protocols
SNMP Multi-Vendor Principles

An Agent for Every Managed Node
– to run SNMP management process

Variables (Objects)
– to describe the state of each device

Information (Format) Specification
–
–
–
–
ANS-1: Standard Object Definition Language
SMI: Defines (SNMP) Data Structures
MIB: Data Structure for (Variables) Objects (Uses SMI)
BER: Basic Encoding Rule (transfer syntax)
(sequence of bytes for transmission)
Saad Haj Bakry, PhD, CEng, FIEE
6
SNMP: Simple Network Management Protocols
SNMP Information Flow
Managed
Node
Agent
Devices
Devices
Device
Using SMI (ASN-1)
Rules to Describe
Objects (Variables)
Object
Object
Object
Object
Object
Object
Variables to
describe
devices
Saad Haj Bakry, PhD, CEng, FIEE
Using BER
Rules to Convert SMI
Data Structures into a
Sequence of Bytes
MIB
Data
Structure
Modules
Sequence
of Bytes
for
Transmission
SNMP Operations
7
SNMP: Simple Network Management Protocols
SNMP Framework
Protocol: “Manager-Agent” interaction
BER: Basic Encoding Rules
MIB: Management Information Base
(Database on managed devices)
SMI: Structure of Management Information
(Rules of describing management information)
Sub-Super-Set of: ASN-1:
Abstract Syntax Notation One
Saad Haj Bakry, PhD, CEng, FIEE
8
SNMP: Simple Network Management Protocols
SNMP Information
Representation
SMI: Structure of Management
Information
 MIB: Management Information
Base
 BER: Basic Encoding Rules

Saad Haj Bakry, PhD, CEng, FIEE
9
SNMP: Simple Network Management Protocols
SMI Data Types (Examples)
INTEGER
A 32-bit integer
BIT STRING
A string of 0 or more bits
Primitive
Data
OCTET STRING A string of 0 or more bytes
Types
NULL
A variable with no value
(place holder)
OBJECT
An officially defined data
IDENTIFIER
type (based on standards)
Additional  User Defined Types
Types
 Application Specific
Saad Haj Bakry, PhD, CEng, FIEE
10
SNMP: Simple Network Management Protocols
SMI: OBJECT IDENTIFIER (1/2)
Top
Level
ccitt (0)
iso (1)
iso-ccitt (2)
org (3)
dod (6)
Saad Haj Bakry, PhD, CEng, FIEE
Internet (1)
11
SNMP: Simple Network Management Protocols
SMI: OBJECT IDENTIFIER (2/2)
Internet (1)
mgmt (2):
Standard
objects
registered by
IANA
(Internet
Assigned
Number
Authority)
mgmt (2)
mib-2 (1)
system (1)
Saad Haj Bakry, PhD, CEng, FIEE
private (4)
security (5)
{Internet (1) 2 1} = {1 3 6 1 2 1}
interfaces (2)
ip (4)
12
SNMP: Simple Network Management Protocols
MIB: Definitions of Objects


MIB is the definition
of “objects” that
should be provided
on each managed
node by the SNMP
“agent”.
An “object” is a
quantity or a field
that describes one
functional aspect of a
device.
Saad Haj Bakry, PhD, CEng, FIEE
MIB objects are
arranged in “groups”
 Some groups relate
to “layer” of the
protocol stack.
 Other groups relate
to the system as a
“whole”
13
SNMP: Simple Network Management Protocols
SNMP MIB Architecture
Simple Network Management Protocol
SNMP
Saad Haj Bakry, PhD, CEng, FIEE
MIB
MIB
MIB
MIB
MIB
MIB
MIB
Application
TCP / UDP
ICMP
IP
ARP
Data Link
Physical
14
SNMP: Simple Network Management Protocols
Internet Protocols
User Interface: E-mail / http / ftp /…
Application
TCP / UDP
ICMP
IP
ARP
Transmission Control
Protocol
Internet Control
Message Protocol
Data Link
Physical
Saad Haj Bakry, PhD, CEng, FIEE
User Data-gram
Protocol
Internet Protocol:
Addressing / Routing /
Congestion Control
Address Resolution
Protocol
Point-to-Point Control: LAN / WAN
Communication Interface: T-R / Links
15
SNMP: Simple Network Management Protocols
BER Structure
Every value transmitted consists of up to 4 fields:
 The identifier
identifies the item that follows
 The length
of the data field in bytes
 The data field
 End-of-contents
flag, if the data length is unknown
Saad Haj Bakry, PhD, CEng, FIEE
16
SNMP: Simple Network Management Protocols
BER Structure: The Identifier
2-bits
1-bit
5-bits
Tag / Type
Data Type
00 universal
01 application
10 context
specific
11 private
0
primitive
1
constructed
Saad Haj Bakry, PhD, CEng, FIEE
Value
Identification Number
17
SNMP: Simple Network Management Protocols
BER Structure: Examples
00000010 00000001
00110001
Identifier
Length
Value
00000011
00000010
01111000
Saad Haj Bakry, PhD, CEng, FIEE
Integer: 49
78
01111001
79
(Hex)
(Hex)
String “xy”
18
SNMP: Simple Network Management Protocols
SNMP Operation
 Principles
 Manager-Agent
 Basic
Interaction
Messages
Saad Haj Bakry, PhD, CEng, FIEE
19
SNMP: Simple Network Management Protocols
SNMP Operation Principles

Asynchronous (Request-Response) Operation
– to run SNMP management process

SNMP Trap
– An “agent” notices a significant event and report the
event to its management stations

Trap Directed Polling
– Polling at “long intervals”, with
– Acceleration on receipt of a trap.
Saad Haj Bakry, PhD, CEng, FIEE
20
SNMP: Simple Network Management Protocols
SNMP Operation
Management
Station
Request PDU
Time
Response PDU
Agent
Managed
Node
PDU: Protocol Data Unit
Saad Haj Bakry, PhD, CEng, FIEE
21
SNMP: Simple Network Management Protocols
Basic Messages (1/2)
Requesting & Updating Variable Values
Originator: Manager / Receiver: Agent



Get-request: Requests the value of one or more
variables
Get-next-request: Requests the value of the next
variable (Alphabetically through MIB)
Get-bulk-request: Requests large transfer (such
as Tables)

Set-request: Updates one or more variables
Saad Haj Bakry, PhD, CEng, FIEE
22
SNMP: Simple Network Management Protocols
Basic Messages (2/2)
Originator: Agent
Receiver: Manager


Response-PDU:
Response Message
Trap-PDU:
Trap Report
Saad Haj Bakry, PhD, CEng, FIEE
Originator: Manager
Receiver: Another
Manager
 Inform-request
Local MIB Description
23
SNMP: Simple Network Management Protocols
Remarks
SNMP Given Review:

Principles

Information

Operation
Saad Haj Bakry, PhD, CEng, FIEE
Future Work:

Practical Systems
Using SNMP

Practical Work

Follow Up
24
SNMP: Simple Network Management Protocols
References

Perkins, D.T., RMON: Remote Monitoring of
SNMP-Managed LANs, Prentice Hall PTR,
Upper Saddle River, New Jersey, 1999

Stalling, W., SNMP, SNMPv2, and CMIP: The
Practical Guide to Network Management
Standards, Addison-Wesley, Reading
Massachusetts, 1993

“Specification of Abstract Syntax Notation One
(ASN.1)”, ISO 8824, December 1987.
Saad Haj Bakry, PhD, CEng, FIEE
25