saad haj bakry, phd, ceng, fiee 1 snmp: simple network management protocol saad haj bakry, phd,...

Saad Haj Bakry, PhD, CEng, FIEE 1

SNMP: Simple Network SNMP: Simple Network Management ProtocolManagement Protocol

Saad Haj Bakry, PhD, CEng, FIEE

PRESENTATIONS IN NETWORK MANAGEMENTPRESENTATIONS IN NETWORK MANAGEMENT


Objectives / ContentsObjectives / Contents

SNMP Principles

SNMP Information RepresentationSNMP OperationRemarks

SNMP: Simple Network Management Protocols


SNMP PrinciplesSNMP Principles

IntroductionComponentsMulti-Vendor PrinciplesInformation FlowFramework



Introduction to SNMPIntroduction 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 (+)



SNMP ComponentsSNMP Components

Managed Node

SNMPManagement

Station

Router AgentBridge Agent

Printer AgentHost Agent

Managed Node

Managed NodeManaged

Node

Management Process

LAN

A Computer Running Management Software (with GUI)



SNMP Multi-Vendor PrinciplesSNMP 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)



SNMP Information FlowSNMP Information Flow

Managed Node

DevicesDevicesDevice

Agent ObjectObjectObjectObjectObjectObject

Variables to describe devices

MIB Data

Structure Modules

Using SMI (ASN-1) Rules to Describe Objects (Variables)

Sequence of Bytes

for Transmission

Using BERRules to Convert SMI

Data Structures into a Sequence of Bytes

SNMP Operations



SNMP FrameworkSNMP Framework

SMI: Structure of Management Information(Rules of describing management information)

Sub-Super-Set of: ASN-1: Abstract Syntax Notation One

MIB: Management Information Base

(Database on managed devices)

BER: Basic Encoding Rules

Protocol: “Manager-Agent” interaction



SNMP Information SNMP Information RepresentationRepresentation

SMI: Structure of Management Information

MIB: Management Information Base

BER: Basic Encoding Rules



SMI Data Types SMI Data Types (Examples)(Examples)

Primitive Data

Types

INTEGER A 32-bit integer

BIT STRING A string of 0 or more bits

OCTET STRING A string of 0 or more bytes

NULL A variable with no value (place holder)

OBJECT IDENTIFIER

An officially defined data type (based on standards)

Additional Types

User Defined Types Application Specific



SMI: OBJECT IDENTIFIER SMI: OBJECT IDENTIFIER (1/2)(1/2)

Top Level ccitt (0) iso (1) iso-ccitt (2)

org (3)

dod (6)

Internet (1)



Internet (1)

mgmt (2) private (4) security (5)

mib-2 (1)

mgmt (2): Standard objects

registered by IANA

(Internet Assigned Number

Authority)system (1) interfaces (2) ip (4)

{Internet (1) 2 1} = {1 3 6 1 2 1}

SMI: OBJECT IDENTIFIER SMI: OBJECT IDENTIFIER (2/2)(2/2)



MIB: Definitions of Objects 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.

MIB objects arearranged in “groups” Some groups relate

to “layer” of the protocol stack.

Other groups relate to the system as a “whole”



SNMP MIB ArchitectureSNMP MIB Architecture

Simple Network Management Protocol

SNMP

MIB ApplicationMIB TCP / UDPMIB ICMP

IPMIB

MIB ARPMIB Data LinkMIB Physical



Internet ProtocolsInternet Protocols

Application User Interface: E-mail / http / ftp /…

TCP / UDP Transmission Control Protocol

User Data-gram Protocol

ICMP Internet Control Message Protocol

Address Resolution Protocol

Internet Protocol: Addressing / Routing / Congestion Control

IPARP

Data Link Point-to-Point Control: LAN / WAN

Physical Communication Interface: T-R / Links



BER StructureBER 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



BER Structure: BER Structure: The IdentifierThe Identifier

2-bits 1-bit 5-bits

Tag / Type

00 universal

01 application

10 context specific

11 private

Data Type

0primitive

1constructed

Value

Identification Number



BER Structure: BER Structure: ExamplesExamples

00000010 00000001 00110001

00000011 00000010 01111000 01111001

Identifier Length Value

Integer: 49

String “xy”

78

(Hex)

79

(Hex)



SNMP OperationSNMP Operation

PrinciplesManager-Agent InteractionBasic Messages



SNMP Operation PrinciplesSNMP 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.



SNMP OperationSNMP Operation

Managed Node

Agent

Management Station

Request PDU

Response PDU

PDU: Protocol Data Unit

Time



Basic MessagesBasic Messages (1/2)(1/2)

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

Requesting & Updating Variable Values



Basic MessagesBasic Messages (2/2)(2/2)

Originator: AgentReceiver: Manager Response-PDU:

Response Message Trap-PDU:

Trap Report

Originator: ManagerReceiver: Another

Manager Inform-request

Local MIB Description



RemarksRemarks

SNMP Given Review:

Principles

Information

Operation

Future Work:

Practical Systems

Using SNMP

Practical Work

Follow Up



ReferencesReferences 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 1 snmp: simple network management protocol saad haj bakry, phd,...

Documents

transmission snmp

gui snmp

snmp framework smi

management software

snmp data structures

basic encoding rules

snmp multivendor principles

manageragent interaction