Network Management

2110472 Computer Networks

Natawut Nupairoj, Ph.D.

Department of Computer Engineering

Chulalongkorn University

Outline

Introduction to Network Management. Overview. Sample Applications.

Simple Network Management Protocol. History of SNMP. Basic SNMP Concepts. MIB Standards. SNMPv3.

ASN.1.

Overview

Typical System Administrator’s Life Manage many hosts and network devices. Detect and response to the PROBLEMS.

Administrators should know the problems BEFORE the users.

Must promise for some Service Level Agreement (SLA) levels System availability. Response time. Throughput.

Overview

What is the scope of network management ? Monitor for problems

Hosts and services. Levels of status: up, minor, major, critical. To reach SLA.

Monitor for tune-up Should we add more network bandwidth ? For how

much ? Detect the intrusion

Intrusion detection against the hackers.

Overview

Why is it so hard ? SLA is usually difficult to achieve without good

planning and tools Availability (uptime) – Five Nines = 99.999% Thus, each host can be down only for

1 Year = 365 * 24 * 60 = 525,600 minutes. 0.001% (acceptable downtime) of 1 Year = 5.256 minutes.

This includes maintenance period !!! How about Six Nines ???

There are MANY…MANY devices.

System Reliability

Cause of downtime (by Gartner Group)

Sample Network Monitoring Applications

There are several network management applications OS Tools

Ping, tracerout, netstat, etc. Freewares

Netsaint, MRTG, snort, etc. Commercial

CA Unicenter, HP Openview, IBM Trivoli, CiscoWorks.

SNMP

Simple Network Management Protocol.

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SMPSNMPv2(parties)security

SNMPv2(community) SNMPv3

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Basic SNMP Concepts

MANAGER

AGENTS

SNMP

MIB

Operational Modes

MANAGER

AGENTS

TRAPS

POLLING

MIB

SNMP StructureMANAGER AGENT

CONNECTIONLESS TRANSPORT SERVICE PROVIDER

SNMP PDUs

UDP

Management ApplicationMIB

SNMP Frameworks – MIB

Management Information Base MIB Objects

Variables that represent the resources of the system. Can have several types of values.

MANAGER AGENT

SNMP

address

name

uptime

SNMP Frameworks - MIB

Structure of Management Information (SMI) Define a standard way to reference the information. Describe what includes / what not for each device.

NEW-MIB:

address (1) info (2)

name (1) uptime (2)

1

130.89.16.2

printer-1 123456

SMI - Example address

Object ID = 1.1 Value of Instance = 130.89.16.2

info Object ID = 1.2

name Object ID = 1.2.1 Value of Instance = printer-1

uptime Object ID = 1.2.2 Value of Instance = 123456

ALTERNATIVE: Object ID = NEW-MIB info

uptime

NEW-MIB:

address (1) info (2)

name (1) uptime (2)

1

130.89.16.2

printer-1 123456

Standard SMIroot

ccitt (0) iso (1) joint-iso-ccitt (2)

stnd (0) reg-auth (1) mb (2) org (3)

dod (6)

internet (1)

security (5)mngt (2) experimental (3) private (4)

mib-2 (1)

directory (1) snmpV2 (6)

enterprises (1)

snmpDomains (1)

snmpProxys (2)

snmpModules (3)

MIB-II – Internet MIB

...

root

ccitt (0) iso (1) joint-iso-ccitt (2)

stnd (0) reg-auth (1) mb (2) org (3)

dod (6)

internet (1)

directory (1) mngt (2) experimental (3) private (4)

mib-2 (1)

system (1) interfaces (2) ... transmission (10) snmp (11) ospf (14) bgp (15)

ethernet (6) token ring (9) fddi (15) adsl (94)

...

...

security (5) snmpV2 (6)

MIB ExampleHost Resources MIB

MIB-2

host (25)

hrSystem (1)

hrStorage (2)

hrDevice (3)

hrSWRun (4)

hrSWRunPerf (5)

hrSWInstalled (6)

hrMIBAdminInfo (7)

hrSystemUptime (1)

hrSystemdate (2)

hrSystemInitialLoadDevice (3)

hrSystemInitialLoadParameters (4)

hrSystemNumUsers (5)

hrSystemProcesses (6)

hrSystemMaxProcesses (7)

SNMP Operations

getNext

response

MIB

manager agent

set

response

MIB

manager agent

get

response

MIB

manager agent

trap

manager agent

PDU Structure

NAME 1 VALUE 1 NAME 2 VALUE 2 ••• ••• NAME n VALUE n

PDU TYPE* ERROR

VARIABLE BINDINGSSTATUSREQUEST

IDERRORINDEX

VERSION COMMUNITY SNMP PDU

variable bindings:

SNMP PDU:

SNMP message:

SNMPv3 – Security Enhancements

MIB

MANAGER

APPLICATION PROCESSES

TRANSPORT SERVICE

MANAGER AGENT

GET / GET-NEXT / GETBULKSET / TRAP / INFORM

SECURE COMMUNICATION

ACCESS CONTROL

ASN.1

Abstract Syntax Notation 1 Similar to BNF notation for programming

language. Define how data should be sent, in what order. The protocol designer must write ASN.1 to define

the protocol Programming language designer uses BNF to define

the grammar of the language. Encode in binary format.

ASN.1 - Example

How can I send an integer 65534 ? 2 bytes: 1111 1111 1111 1110 Big-endian or little-endian ?

Sender uses little-endian, receiver uses big-endian. 1111 1110 1111 1111 = 65279

What if I want to send a whole structure ?struct {char code;int x;

}

ASN.1 Syntax Definition

Define a data type Define based on built-in types and other data

types defined in the file. Built-in types: INTEGER, OCTET STRING,

REAL, BOOLEAN, etc. Newly-defined data type can be complicated

SEQUENCE, SEQUENCE OF, CHOICE, etc.

Format <name> ::= <description -- components>

ASN.1 Examples

---- The currency codes from ISO 4217-- are used to identify a currency --Currency ::= OCTET STRINGObjectId ::= INTEGER

DateTime ::= SEQUENCE { timeOffsetCode TimeOffsetCode,

localTimeStamp LocalTimeStamp}

ASN.1 Encoding Rules

Syntax definition defines the components of the data.

Encoding defines how to actually store the data.

Data can be encoded in several ways. Basic Encoding Rule (BER). Distinguished Encoding Rule (DER). Packed Encoding Rule (PER).

BER Encoding

Basic Encoding Rule (BER) Tag Length Value (TLV).

TAG LENGTH VALUE

MyId ::= [APPLICATION 12] INTEGER

12 4 1234(this is not the actual encoded data.)

BER Encoding

Constructed Encoded Form

T L T L T L V T L V

DateTime ::= [APPLICATION 83] SEQUENCE

{

timeOffsetCode TimeOffsetCode,

localTimeStamp LocalTimeStamp

}

TimeOffsetCode ::= [APPLICATION 232] Code

LocalTimeStamp ::= [APPLICATION 16] NumberString

Code ::= [APPLICATION 243] INTEGER

References J. Kurose and K. Ross, Computer Networking: A Top-Down

Approach Featuring the Internet, Addison Wesley, 2001. Netsaint, http://www.netsaint.org. The SimpleWeb Tutorials, http://www.simpleweb.org/tutorials/. Electronic and telecommunication Institute, Lessons about SNMP,

http://www.et.put.poznan.pl/snmp/main/mainmenu.html. Yoram Cohen, SNMP – Simple Network Management Protocol,

http://www.rad.com/networks/1995/snmp/snmp.htm.