Introduction to Network Management
6 May 2003
C.S. Hong
Kyung Hee
University
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Spring 2003
Contents
 SNMP Management Concepts
 SNMP Management Information
 XML-based Network Management
 Network Monitoring
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SNMP Network Management
Concepts
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Introduction
 ICMP (Internet Control Message Protocol) for transferring control
message from routers and other hosts to a host : the late 1970s
useful features : echo/echo-reply message pair, time stamp and time
stamp reply message pair
a management tool : PING (Packet Internet Groper)

verifying the operation of a server

observing variations in round-trip times and in datagram loss rates
 Internet growing in the late 1980s
SGMP (Simple Monitoring Protocol) in Nov. 1987 ----> SNMP
HEMS (High-level Entity Management System) : generalization of Host
Monitoring Protocol (HMP)
CMIP over TCP/IP (CMOT)
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Introduction (cont’d)
 In 1988, IAB approved further development of SNMP as short-term
solution and CMOT as the long-term solution
As a short-term solution

immediate implementation of SNMP based on SGMP
–
TCP/IP based network
–
IETF was responsible for the implementation
–
keep the protocol simple
–
focus on fault and configuration management
As a long-term solution

CMIS/CMIP for future requirements

developed by the ISO

non protocol specific (for use of all network devices)
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Evolution of SNMP
 Development of a remote monitoring capability for SNMP
 RMON (Remote Monitoring) MIB and addition to SNMP MIB for monitoring
 Vendor-independent SNMP MIB and Vendor-specific SNMP MIB
 SNMP v2 : dealing with security aspects
developed by members of the networking community in 1993, and revised in
1995
solve some of deficiencies with SNMP



only for IP network
relatively unsecured
efficient table retrieval
 SNMP v3 in 1998 : specifying use of cryptographic algorithms
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SNMP-Related Standards by IETF
 Foundation specifications
Structure and Identification for Information for TCP/IP-based networks
(RFC 1155)
Management Information Base for Network Management of TCP/IPbased Internet: MIB-II (RFC 1213)
Simple Network Management Protocol (RFC 1157)
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Network Management Architecture and Its Key Elements
for TCP/IP Network
 Management station having :
a set of management application for data analysis and fault recovery
an interface for the network manager to monitor and control the
network
a database of information extracted from the MIBs of all the managed
entities in the network
the capability of translating the network manager’s requirements into
the actual monitoring and control of remote elements in the network
 Management agent
managed from a management station
providing the management station with important but unsolicited
information
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Network Management Architecture and Its Key Elements
for TCP/IP Network (cont’d)
 MIB (Management Information Base)
representing resources as objects
data variables representing one aspect of the managed agent
management station performs the monitoring function by retrieving
the value of MIB objects
 Network management protocol
linking management station and agents
key capabilities of SNMP

get : retrieving the value of objects at the agent

set : setting the value of objects at the agent

trap : notifying the management station of significant events
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Network Management Protocol Architecture
 SNMP implemented on the top of UDP ( or TCP), IP and relevant
network-dependent protocol (ex, Ethernet, FDDI, X.25, ATM,…)
Host
Management station
Network
manager
Agent Process User process
Manager Process
SNMP
SNMP
Central
MIB
UDP
UDP
TCP
IP
IP
Network-dependent
Protocol
Network-dependent
Protocol
Router
Host
Agent Process User processes
SNMP
Internetwork
Manager Process
SNMP
FTP, etc
UDP
UDP
TCP
IP
IP
Network-dependent
Protocol
Network-dependent
Protocol
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FTP, etc
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Types of SNMP Messages
SNMP agent
SNMP management station
Management
application
Application
manages objects
SNMP Messages
Managed resources
SNMP managed objects
SNMP Manager
SNMP agent
UDP
UDP
IP
IP
Network-dependent
protocols
Network-dependent
protocols
Network or Internet
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Proxies
Proxy agent
Management station
Mapping function
Manager Process
Agent Process
SNMP
SNMP
UDP
UDP
IP
IP
Network-dependent
Protocol
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Management Process
Protocol
architecture
used by
proxied device
Network-dependent
Protocol
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Proxied device
Networkdependent
Protocol
Protocol
architecture used
by proxied device
Network-dependent
Protocol
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SNMP Management Information
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SNMP Management Information
 Database containing information about the elements to be managed : MIB
 Each resource to be managed, to be represented by object
 MIB : structured collection of such object having the form of tree
 Structure of Management Information (SMI)
Specified in RFC 1155
Providing a standardized technique for defining the structure of a particular
MIB
Providing a standardized technique for defining individual objects, including
the syntax and the value of each object
Providing a standardized technique for encoding object values
SMI Data Type Additions To Structure of Management Information Version 2
(SMIv2) and Structure of Management Information Version 1 (SMIv1) : draftperkins-smi-addition-00.txt

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The new data types are Integer64, Unsigned64, Float, Double, and DiscUnion
(discriminated union)
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Defining objects
 MIB (Management Information Base)
a precise definition of the information accessible through a network
management protocol
each device must use the format for displaying information that is
defined by the MIB
RFC 1052


define an extended MIB for use with SNMP and CMIS/CMIP
is no longer realistic
RFC 1065: “Structure and Identification of Management Information
for TCP/IP based Internets (SMI)”

describe the syntax and type of information available in the MIB for TCP/IP
networks
RFC 1066



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use the rules of the SMI
present the first version of the MIB for TCP/IP
known as MIB-I
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Defining objects (cont’d)
RFC 1155 (SMI)

RFC 1065 later was adopted by the IAB as a full standard

four primitive data type
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–
INTEGER
• 32bit value in two’s complement representation
• -2147483648 ~ 2147483647
–
OCTET STRING
• zero or more octets
• 0 ~ 255
• represent a text string
–
OBJECT IDENTIFIER
• a sequence of integers
• traverse a hierarchical MIB tree
–
NULL
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Defining objects (cont’d)
RFC 1156

allow for expansion of the MIB for vendor specific enhancement
RFC 1158

propose a second MIB (MIB-II)

extend the information base defined in MIB-I

Note: most network devices have software agent that support MIB-II and their own
private extensions
Each MIB would focus on a specific technology

RFC 1743: IEEE 802.5 Token Ring Interface type MIB

RFC 1757: Remote Network Monitoring MIB (RMON)

RFC 1513: FDDI Interface type MIB

RFC 1493: Bridge MIB
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MIB Structure
 Leaf objects of the tree to be actual managed objects to represent
some resource, activity, or related information
 Object identifier : a unique identifier for particular object type
Serving as the name of an object
internet OBJECT IDENTIFIER :: = { iso (1) org(3) dod (6) 1}
therefore, internet node’s object ID : 1.3.6.1
four nodes under the internet node

directory

mgmt ----> mib-1, mib-2

experimental

private
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MIB Structure (cont’d)
 Object Identifier
ISO ASN.1 (Abstract Syntax Notation One) Syntax

a subset of ASN.1 defines the syntax for the MIB

use the tree architecture to organize all available information
–
labeled node
–
object identifier (OID) and text description
Object ID consisting of sequence of integers

for example : object ID for tcpConnTable : 1.3.6.1.2.1.6.13
iso org dod internet mgmt mib-2
tcp
1
6
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3
6
1
2
1
19
tcpConnTable
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MIB Tree
 Traversal of the MIB tree
root node

itu-t (0), administered by the ITU-T

iso (1), administered by the ISO

joint-iso-itu-t (2), jointly administered by ISO and ITU-T
–
internet: OID= 1.3.6.1 or {iso org(3) dod(6), 1}
ITU-T(0)
ISO(1)
joint-ISO-ITU-T (2)
…. org(3) …..
….. dod(6) …..
….. internet (1) …..
directory(1)
……
mgmt(2) ….
mib(1)
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Experimental(3)
private(4)
enterprises(1)
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MIB Tree (cont’d)

directory (1)
–

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reserved for future use
mgmt(2)
–
MIB-I originally assigned OID 1.3.6.1.2.1 or {mib 1}
–
MIB-I has been superseded by MIB-II
–
system(1): network device operating system
–
interfaces(2): network interface specific
–
address translation(3): address mappings
–
ip(4): Internet protocol specific
–
icmp(5): ICMP specific
–
tcp(6): transmission protocol specific
–
udp(7): user datagram protocol specific
–
egp(8): exterior gateway protocol specific
–
cmot(9): CMIP on TCP specific
–
transmission(10): transmission media specific
–
snmp(11): SNMP specific
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MIB Tree (cont’d)

experimental (3)
–

experimental protocols and MIB development intended to enter the standards
track
private(4)
–
used to specify objects defined unilaterally
–
enterprises(1) or {private 1}
•
•
•
an organization that has registered its own specific extensions to the MIB
vendor-specific MIBs are found
OID (1.3.6.1.4.1)
OIDs represent each manageable object with a unique sequence of numbers
and names

SNMP uses the number as an abbreviated form of the name
–
to make requests for data values
–
to identify each response that carries the values
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MIB : An Example
tcpMaxConn OBJECT-TYPE
SYNTAX INTEGER
ACCESS read-only
STATUS mandatory
DESCRIPTION
“The limit on the total number of TCP connections the entity can
support. In entities where the maximum number of connections is
dynamic, this object should contain the value -1.”
::= { tcp 4 }
* OID :1.3.6.1.2.1.6.4
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Macro object definition
 Object : having a type (syntactic description) and value
 To extend ASN.1 to define new types and their values
 Macro definition : specifying the syntax of a set of related types
 Macro instance : an instance generated from a specific macro
definition
 Macro instance value : representing a specific entity with a specific
value
 Macro used for the SNMP MIBs : RFC1155 for MIB-I, RFC 1212
(concise MIB definitions) for MIB-II
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Private MIBs
 MIB has been designed to accommodate growth and to provide
flexibility for adding new objects.
 Private extensions can be added to the private subtree
 The management station must be loaded with the private MIB
structure
 The potential for difficulty arises when the two are from different
vendors
Most vendors supply both a text version and a formal description of
their MIB extensions
But, vendors can use different formats
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SNMP Operation
The five SNMPv1message types (RFC1157)

Get-Request: retrieve information from device

Get-Response: agent responds to the Get-Request

Get-Next-Request: ask for the next specific object

Set-Request: for remote configuration parameter

Trap: an unsolicited message
Data Network
Managing host
station
MS-DOS
agent
agent
Host
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Router
agent
agent
Terminal server
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agent
Device
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SNMP Operation (cont’d)
Format of SNMP
Version
Version
Version
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Community
Community
Community
PDU
Request
0
Name X
0
type
ID
Get-Request, Get-Next-Request, Set-Request
PDU
type
PDU
type
Request Error
ID
status
Get-Response
Enterprise
Error
index
Agent Generic
addr
trap
Trap
Layer 7
SNMP
Layer 6
ISO presentation
Layer 5
ISO session
Layer 4
UDP
Layer 3
IP
Layer 2
ISO data link
Layer 1
Physical
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Name X
Value X
……..
Value X
……...
Specific Time Name X Value X
trap
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SNMP Operation (cont’d)
SNMP trap

an unsolicited message an agent sends to a station

inform the server about the occurrence of specific event

seven types of SNMP traps (MIB-II)
–
coldstart of a system: reinitializing itself such that its configuration or protocol
has changed
–
warmstart of a system: reinitializing itself such that its configuration or protocol
has not changed
–
link down: a specific link has failed
Managing host
Data Network
station
Device
agent
Link failure
Trap: interface #2, link down
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SNMP Operation (cont’d)
–
link up: a specific link has come up
–
failure of authentication: a request does not provide proper authentication
–
EGP (Exterior Gateway Protocol) neighbor loss
• EGP is a reachability protocol used between data networks
–
enterprise specific
• a vendor to provide additional functionality that complements the generic
traps
security

community string
–
station sends a particular password with each message
–
the password is referred to as the SNMP community string
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SNMP V2 & V3
 SNMPv2
The key enhancements to SNMP that are provided in SNMPv2

Structure of Management Information (SMI)

Manager-to-manager capability

Protocol operations
Most noticeable change in protocol operations


GetBulkRequest PDU : enabling the manager to retrieve large blocks of data
efficiently. It is well suited to retrieving multiple rows in a table
InformRequest PDU : enabling one manager to send trap of information to another
Additional types

Integer32

Counter32

Gauge32

Unsigned32

Counter64
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SNMP V2 & V3 (cont’d)
 SNMPv3
Adding cryptographic algorithms
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RMON 1 and 2
 Defining a remote monitoring MIB that supplements MIB-II
 Providing the network manager with vital information about the
internetwork
 Providing significant expansion in SNMP functionality
 RMON-Related RFCs
RFC 1513 : Token Ring Extensions to the Remote Network Monitoring MIB
RFC 1757 : Remote Network Monitoring Management Information Base
RFC 2021 : Remote Network Monitoring Management Information Base II
RFC 2074 : Remote Network Monitoring MIB Protocol Identifiers
RFC 2613 Remote Network Monitoring MIB Extensions for Switched Networks
Version 1.0. (proposed standard) June 1999
RFC 2819 : Remote Network Monitoring Management Information Base, May
2000. (obsolete RFC1757)
RFC 2895 : Remote Network Monitoring MIB Protocol Identifier Reference,
August 2000. (obsolete RFC 2074)
RFC 2896 : Remote Network Monitoring MIB Protocol Identifier Macros, August
2000. (informational)
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RMON Goals
 Defining standard network-monitoring functions and interfaces for
communicating between SNMP-based management consoles and remote
monitors
 Designing Goals for RMON described in RFC 1757
off-line operation : to limit or halt the routine polling of a monitor by network
manager
Proactive monitoring : using running diagnostics and logging network
performance
Problem detection and reporting
Value-added-data : performing analyses specific to the data collected on its
subnetwork

ex) analyzing subnetwork traffic to determine which hosts generate the most traffic or
errors on the subnetwork
Multiple managers

for improving reliability

for performing different functions (ex, engineering and operations)

for providing management capability to different units within an organization
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RMON Goals (cont’d)
 A system that implements the RMON MIB is referred to as an
RMON probe.
no different from any other SNMP agent
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RMON Goals (cont’d)
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OID Tree for RMON
ITU-T(0)
iso(1)
joint-iso-ITU-T (2)
…. org(3) …..
….. dod(6) …..
….. internet (1) …..
directory(1)
……
mgmt(2) ….
Mib-2(1)
Experimental(3)
private(4)
enterprises(1)
system(1) interfaces(2) at(3) ip(4) icmp(5) tcp(6) udp(7) egp(8) cmot(9) transmission(10) snmp(11) …...Rmon(16)……...
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Network-Layer Visibility of RMON
 RMON probe with RMON1 can monitor all of the traffic on the
LANs, or can capture all of the MAC-level frames and read the
MAC-level source and destination addresses in those frames.
But, no way of determining the ultimate source of incoming traffic
arriving via the router or the ultimate destination of outgoing traffic
leaving via the router.
 With RMON2, the RMON probe has the capability of seeing above
the MAC layer by reading the header of the enclosed network-layer
protocol, which is typically IP.
analyzing traffic passing through the router to determine the ultimate
source and destination.
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The RMON MIB

rmon (mib-2, 16)
statistics (1)
protocolDir (11)
history (2)
ProtocolDist (12)
alarm (3)
addressMap(13)
host (4)
nlHost (14)
hostTopN (5)
nlMatrix (15)
matrix (6)
alHost (16)
filter (7)
alMatrix (17)
capture (8)
usrHistory (18)
event (9)
probeConfig (19)
rmonConformance (20)
tokenRing (10)
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RMON1
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RMON2
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XML-based Network Management
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Introduction
 eXtensible Markup Language (XML)
 A simplified subset of the Standard Generalized Markup Language (SGML)
 XML is an emerging technology for Web-based applications and has been
in the spotlight.
 XML has many advantages
Simplicity, openness, extensible, inexpensive
 Most people believe that XML will succeed much more than HTML, HTTP,
Web, Java
 Advantages in XML-based network management
Easy to learn: not management domain specific technology
Large supporting tools and technology: Low development cost
High compatibility with legacy management technology: Integrated
management.
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XML : What is XML ?
 What does “XML” stands for?
eXtensible: not a fixed format, customizable.
Markup: used to define things.
Language: used to communicate or describe and encapsulate its information
and pass it.
 XML was designed to describe data.
Document Type Definition (DTD) or XML Schema is used.
XML is self-descriptive.
 XML is free and extensible.
XML allows the author to define his own tags.
 XML is a compliment to HTML.
XML will be used for describing data and HTML for displaying same data.
 XML is a future Web technology.
Quick standard process, large support by vendor.
Common tool for all data manipulation and data transmission.
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XML : An Example
 A Telecom example
<?xml version=“1.0” ?>
PI target
<?xml:stylesheet type="text/xsl" href="schema.xsl"?>
PI value
<n-entityCreation id="1">
<ems id="TaskCenter">
<mgdEltR1 id="NE1" adminState="unlocked“ opState="enabled">
<equipHolder id="1" equipHolderType="Bay">
<equipHolder id="3" holderType="Shelf">
<equipHolder id="4" holderType="Slot">
</equipHolder>
</equipHolder>
</equipHolder>
</mgdEltR1>
</ems>
PI : Processing Instruction
</n-entityCreation>
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XML : Technology Map
WAP, XHTML
Standard
DTD, XML Schema
Validate
Program
Scripts
Database
Editor(file)
XSL
Define
Generate
XSLT
Input
XPath
Web
Brower
Input
XML
Input
Input
Parse
Dump
SOAP
Exchange
Remote
System
DOM
Process
Program
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XML : DTD and XML Schema
 DTD (Document Type Definition)
Defines the document structure with a list of legal elements
Can be declared inline in XML document, or as an external reference.
 XML Schema
A successor to DTD.
Support for Data Types
Provides inclusion and derivation mechanisms
Uses XML as encoding syntax
 Why use DTD/XML Schema?
Each XML file can carry a description of its own format.
To verify the data you received or your own data.
Independent groups of people can agree to use a common DTD for
interchanging data.
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XML : DTD Example
<!DOCTYPE lecturer [
<!ELEMENT lecturer (name, (email | hp)?)>
<!ELEMENT name (#PCDATA)>
<!ELEMENT email (#PCDATA)>
<!ATTLIST lecturer class CDATA #REQUIRED> ]>
seminar.dtd
Verification
Description
<?xml version=“1.0”?>
<!DOCTYPE lecturer
SYSTEM “seminar.dtd”>
<lecturer class=“XML”>
<name>cshong</name>
<email> … </email>
</lecturer>
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<?xml version=“1.0”?>
<!DOCTYPE lecturer
SYSTEM “seminar.dtd”>
<lecturer class=“XML”>
<name>cshong</name>
<email> … </email>
</lecturer>
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XML : DOM
 Document Object Model (DOM)
 Definition
A programming interface to access and manipulate XML documents
 Objectives
To provide a standard programming interface to a wide variety of
applications
 can create an XML document, navigate its structure, and add, modify,
or delete its elements
 can be used with any programming language on any operating
system
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Spring 2003
XML : DOM example
<?xml version=“1.0”?>
<lecturer class=“XML”> <name> cshong </name>
</lecturer>
Parsing
Serialization
document
lecturer
class
DOM API
DOM
Tree
Applications
written in
any
language
name
juht
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Applicability of XML
 Basic management tasks
Management Information Modeling.

Description framework for managed resource to managed object.
Management Information Realization.

Guarantees of consistency between managed resource and managed
object.
Management Information Distribution.

Exchange of management information between management applications.
Management Information Analysis.

Process of management information production from collected
information.
Management Information Presentation.

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User interface for display management information or taking management
command from operators.
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Basic Management Tasks
Agent
Modeling
Realization
Distribution
Manager
Presentation
Analysis
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Management Information Modeling
 Standard Information model
SNMP
TMN
DMTF
XML
SMI
GDMO
CIM
XML Schema
MIB-II
G.721
CIM v.6
No standard yet
Object-based
Object-oriented
Object-oriented
Object-oriented
Tool
Models
Approach
 XML Schema for management information modeling
Advantages

Easy to learn, not domain specific technology.

Use of powerful and convenient graphical XML editor.

Modeling result is concise and easy to read.

Secondary benefits – validation, sample data generation.
Disadvantage

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No standard models, but easy to translate from standard information models.
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Management Information Realization
 Standard management frameworks leave it completely unspecified viewed as a “local matter”.
 Model specification serves as a starting point for the coding of the agents.
For Web interface and CLI, the model specification was not provided.
For SNMP, MIB compilers have been used to generate MIB stubs.
The stubs are supplemented with the code for actual access to resources.
 There is no common interface or data format between managed resource
and management agents such as CLI, SNMP, Web.
Large development cost and footprint.
Consistency problem by multiple access to single managed resource.
 XML for management information realization
XML can be used for middleware between agents and managed resources.
Low footprint solution.
Various methods can be used for XML generation.
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Management information distribution
 Communication between management applications
Agent ↔ Manger, Manager ↔ Manager
 Standard management communications
Protocol
Operation
SNMP
TMN
DMTF
XML
SNMP/UDP
CMIP
Operations/HTTP
SOAP or HTTP
Get, Set,
M-Get, M-Set , MCreate, M-Delete, MAction
GetInstance, SetInstance,
GetClass, etc. (23
Operations)
Unspecified
Trap
M-Event_Report
Unspecified
Unspecified
ASN.1
ASN.1
XML
XML
GetNext,
Response
Notification
Encoding
 North bound interface is usually based on CORBA.
XML and CORBA are interoperable technologies.
 XML does not say anything about communication protocol, Implicitly
HTTP is used.
Reliable, efficient by compression, highly secure, high connectivity.
Flexible by use of SOAP.
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Management Information Analysis
 This has not been standardized and based on data processing such as
sorting, filtering, logging and correlating.
 Management platforms provide basic management functionality and
development environment.
Their price is usually very expensive.
Customization requires large amount of time and effort.
In most cases, they do not depend on standard technology.
 Recently, CORBA has been used widely as an implementation platform for
management systems.
 XML for management information analysis.
XML is a standard data processing tool.
Many supporting tools (such as database) are available.
Lots of developers having XML knowledge.
Kyung Hee
University
53
Spring 2003
Management Information Presentation
 This allows user interactive access to the management system.
Text+
Windows#
Web*
XML
Ubiquity
Best
Bad
Good
Good
Interactivity
Bad
Best
Good
Good
Development cost
Low
High
Middle
Low
User-friendliness
Worst
Good
Best
Best
+: Include telnet connection.
#: MS-Windows or X-Windows
*: Without use of XML technologies.
 XML for management information presentation
Separation with display and data in Web environment.
Platform independent standard display technology.
Device dependant display support.
Ubiquitous management user interface.
User-friendly graphic interface.
Kyung Hee
University
54
Spring 2003
State of the Art for XML-based NM
 Research work
Complimentary approaches to SNMP

eXtensible Network and System Management Instrumentation.

SNMP to XML translator

XML/SNMP Gateway
Improvement approaches to Web-based network management

Direct Web Interface for Device Configuration

XML-based Device Configuration
New Management Architectures

XML-based Service Configuration

Web-based Integrated Management Architecture

XML-based Network Management Architecture
 Standard Activities
Web Based Enterprise Management (WBEM)
Kyung Hee
University
55
Spring 2003
SNMP to XML Translator
 Applications of SNMP to XML translator
Web
Server
1. Encoding SNMP MIB data
XML/HTTP
SNMP
Agent
2. Information analysis or presentation for SNMP MIB data
SNMP
3. Specification translation for SNMP to XML gateway
XML
Kyung Hee
University
GW
SNMP
56
Spring 2003
XML/SNMP Gateway
 What is XML/SNMP Gateway?
Relays management information and operations between SNMP agent and
XML-based manager system.
While preserving the legacy SNMP agent, one can develop XML-based
manager by using XML technology.
Two basic requirements for the gateway

Specification translation: SNMP MIB  XML
–

Interaction translation: SNMP Operations  XML Operations
–
Kyung Hee
University
For understanding the management information exported by SNMP
agent.
For supporting interaction between two management applications
57
Spring 2003
Direct Web Interface to Managed Devices
 Traditional Approach
Embedded
Web Server
HTML or Java / HTTP
Result of embedding small Web server into network device.
Ubiquitous, simple but powerful, user-friendly device management user
interface.
 XML Approach (EmWeb XML parser)
Embedded
Web Server
XML & XSL / HTTP
XML generation by program is enough small solution to be embedded.
Separate display format and data generation.
XML parser can save development cost by generating backend stub code
based on XML schema.
Kyung Hee
University
58
Spring 2003
Network Monitoring
Kyung Hee
University
59
Spring 2003
Generic Metrics
 Availability
Connectivity
Functionality
 Loss
One way loss
Round trip loss
 Delay
One way delay
Round trip delay
Delay variance
 Utilization
Bandwidth
Throughput
Kyung Hee
University
60
Spring 2003
Network Monitoring
 Active Approach
 Performed by sending test traffic into network
1) Generate Test packet periodically or on-demand
2) Measure performance of test packet or response
3) Take the statistics
 Impose extra traffic on network and distort its behavior in the process
 Used to monitor network performance
e.g., Availability, Delay, Loss
Kyung Hee
University
61
Spring 2003
Network Monitoring (cont’d)
 Passive Approach
 Carried out by observing normal network traffic
1) Collect network flow from device or generate it after capturing
2) Perform analysis for the purpose
 Using high-performance computing device (harder as traffic rates increase)
 Used to perform traffic characterization analysis
Spatial, temporal and composition
Kyung Hee
University
62
Spring 2003
Questions ?
Kyung Hee
University
63
Spring 2003