SNMP ( Simple Network Management Protocol ) based Network Management
Network Management week#1
Transcript of Network Management week#1
-
8/10/2019 Network Management week#1
1/23
1
Northwestern Polytechnic University
1
CS 565 Network Management
Dr. Qingsong Zhang
Northwestern Polytechnic University
2
Class Notice:
13 weeks. Every Wed. 6:00 pm
Text book: SNMP, SNMPv2, SNMPv3,
and RMON 1 and 2.
You are required to attend all the
classes.
CS470, CS503 prerequisite.
Northwestern Polytechnic University
3
Why manage?
Enterprise networks are becoming increasingly
distributed and complex environments due to a
number of factors:
The rapidly increasing number of network nodesexponentially increases network complexity;
IS managers must be masters of more domains, as theirremit includes managing network traffic across
expensive WAN pipes, as well as LANs, VLANs andVPNs;
Increasing use of delay-sensitive, bandwidth intensiveapplications such as video-conferencing, adds a new
dimension to network management;
Northwestern Polytechnic University
4
Why manage?
Networks are now mission critical for the vast majority
of enterprises;
The efficiencies of the network are more visible to
customers and clients than ever before with the advent
of e-commerce.
QoS: Bandwidth, delay, recovery.
So, Why management?
More complex network.
Downtime costs real money.
QoS: Bandwidth, delay, recovery.
Northwestern Polytechnic University
5
Course Goals
Rapid development in computer and data
networking technology.
Explosion in the variety of equipment and
networks offered by vendors. Fundamental to the operation of such tools and
applications in a multivendor environment are
standardized techniques for representing and
exchanging information relating to network
management.
Northwestern Polytechnic University
6
Course Goals, Cont.
Network management is one of thekeywords when it comes to build largeand heterogeneous networks.
Despite they use the word quite often,only few people know exactly what it reallymeans.
And still fewer people even designed andimplemented a management system or amanagement concept for a real network.
-
8/10/2019 Network Management week#1
2/23
2
Northwestern Polytechnic University
7
Course Goals, Cont.
A network can be managed on severaldifferent levels:
The lowest level is networkmaintenance.
The next level is called configurationmanagement.
Northwestern Polytechnic University
8
Network Management
This is where decisions are made involving theplanning of the physical and logicalconstruction of the network.
The configuration is defined by the deviceconnected to the network, how they areconnected, and what is used to connect them.
Configuration decisions include how tosegment the routers, what kind of systemmanagement software to use on the hosts,whether to provide fixed IP address or use aDHCP server, and how we convince the peoplein finance that we need T1 service for ourinternet connection.
Northwestern Polytechnic University
9
Network Management
Anger one of these people, and theyllconfigure the router on your segment toswallow all packets originating from yourworkstation--and they claim for days that theyare working on the problem.
Next higher level is the networkadministrators. A netadmin is eitherchasing or being chased
Northwestern Polytechnic University
10
Network Management
The highest level is
the network users themselves
the most helpless managers of anynetwork.
The real network manager just want tokeep the users from accidentally (orpurposely) screwing up the network.
Northwestern Polytechnic University
11
Course Goals, Cont.
Give you a solid fundament of networkmanagement theory that enables you tofind a quick entrance to any aspect ofnetwork management practice, forexample development of managementsystems, research issues and findingmanagement concepts for existing or newnetworks.
How to Manage?
Manage by hand
Still usual in many small and medium
sized LANs.
Admin can only react when a faultoccurs.
Difficult to handle when network grows.
Demand for a skilled operator on every
location.
Slow and expensive when network becomes
larger and/or more complexNorthwestern Polytechnic University
12
-
8/10/2019 Network Management week#1
3/23
3
Centralized Management
Less personnel
Faster reaction
No need to go "on location"
Effect on the rest of the network can be
monitored
No isolated view on one device only
Most interesting in WANs
Northwestern Polytechnic University
13
Centralized Management
Two Options:
Connecting a pool of central console to
each deviceStill done in mainframe environments and in very
critical areas
Often in conjunction with a switch matrix
Expensive
Very bad flexibility, bas scalability
But still works when the network down!
Northwestern Polytechnic University
14
Centralized Management
Each device presents a management
entity that is accessible from the
networkObviously, the second alternative is primarily used today,
but the first is still an option
Example: extra remote console via a terminal serverfor important backbone systems
First systems of this kind were just as proprietary as the
consoles
Example: DEC LAT printer infrastructure
Still one central console for each class of devices
Creates "management islands"
In some areas this is still a major problem
Northwestern Polytechnic University
15
Northwestern Polytechnic University
16
Course Goals, Cont.
Give you a solid fundament of networkmanagement theory that enables you tofind a quick entrance to any aspect ofnetwork management practice, forexample development of managementsystems, research issues and findingmanagement concepts for existing or newnetworks.
Northwestern Polytechnic University
17
Description
Review several protocols which are important for
network management.
Provide a comprehensive introduction to SNMP
based protocols, the construction of the
management information base (MIB).
Use RMON probes to monitor the network.
Emphasis on understanding how to retrieve data
elements and how to interpret the effect of values
retrieved.
Text book
SNMP, SNMPv2, SNMPV3 and RMON 1 and 2,
By William StallingsNorthwestern Polytechnic University
18
CS 565 Network Management
Dr. Qingsong Zhang
1. Network Management Fundamentals
-
8/10/2019 Network Management week#1
4/23
4
Northwestern Polytechnic University
19
Network Management
Fundamentals
Motivation
History
What exactly is network management
Discussion of several definitions
Roles of network management
Future developments
Northwestern Polytechnic University
20
Motivation
The network and its associated
resources and distributed
applications become indispensable
to the organization.
More things can go wrong, disabling
the network or a portion of the
network or degrading performance to
an unacceptable level.
Northwestern Polytechnic University
21
Motivation
Professional Support corporate planning and to provide
professional leadership in the technical area
Financial Is not an expense or cost center
Technical Provide additional services or add new users
Security
Provide services only to authorized users
Northwestern Polytechnic University
22
OSI Functional Areas
Configuration management
Configuration and monitoring of resourcesfor normal operation
Fault management
Detection, localization and repair of faults
Performance management Performance measurements and
comparison with expected values
Northwestern Polytechnic University
23
OSI Functional Areas
Performance management (cont.)
Detect approaching problems and
configuration mistakes
Network simulation (!)
Security management
Provision and configuration of security
services in the network
For example TACACS (+) for device access
Northwestern Polytechnic University
24
OSI Functional Areas
Accounting
Logging and export of data for billing
Supervision of service access
Most important in carrier networks
But will become a subject in corporate networks also
(for Qos issues)
A real challenge: it's not easy
Most companies have to throw quite a lot of moneyinto this to get it working
Example: 75% of EWSD software is accounting
-
8/10/2019 Network Management week#1
5/23
5
Northwestern Polytechnic University
25
History
until 1970
management by hand with local operators
use of local consoles and service switches
and LEDs
1970-1980
first centralized management systems
proprietary
Northwestern Polytechnic University
26
History
1981-1989
development of first international network
management standards
from 1987 first standard-conformant
products
example: SunNetManager (with many proprietary
additions)
coexistence with proprietary products
Northwestern Polytechnic University
27
History
1989-today
further development of standards
especially for interworking of management
products and distributed management
slow progress
development of management frameworks
that are based on existing standards
ITU TMN, OSF/DME (R.I.P.), OMNIPoint
(small) improvements of interoperability
between different manufacturersNorthwestern Polytechnic University
28
History
Roots in the mainframe and
minicomputer era with computer
manufacturers and third-party
software developers producing
proprietary products in 1960s.
Interoperability problem resulted in
the development of a series of
standards. (SNMP, RMON, MIB,)
Northwestern Polytechnic University
29
What is Network Management?
Access (within organizational policy
restrictions) to any of the network
resources at any time.
In other words, a user with thecorrect authorization should be able
to make use of any of the
organization (or Internets) network
resources at any time of the day or
night efficiently.
Northwestern Polytechnic University
30
Definition
Network management is the process of
using hardware and software by trained
personnel to monitorthe status of network
equipment and transmission facilities;
question end users, vendors andcommunication carrier personnel; and
implement or recommend actions to
alleviate outage and/or improve
communication performance, as well as
conduct administrative tasks associated
with the operation of a network.
-
8/10/2019 Network Management week#1
6/23
6
Northwestern Polytechnic University
31
Role of Network Management
Critical in the business world.
Indispensable.
A network that always works becomes
increasingly important for more and more
companies and institutions
downtime costs real money
new multimedia applications put higher demands
on the infrastructure
QoS: bandwidth, delay, recovery
Northwestern Polytechnic University
32
Future Development
Use of automated network management tools.
Tune the performance by itself.
Improve the security.
Web based management system.
Coexistence of different management standards and
frameworks
TMN will become more important
Combinations of different (distributed) management
systems in one network under a common GUI
Java-based
CORBA export functions (statistics, billing, event monitoring,
etc.)
Northwestern Polytechnic University
33
CS 565 Network Management
Dr. Qingsong Zhang
2. Overview of Network Management Standards
Northwestern Polytechnic University
34
Overview of Network
Management Standards
How todays standards were
developed?
Comparison: OSIMAN, SNMP, TMN
Other standards and developments
Basics - What are in common?
Northwestern Polytechnic University
35
Standard
Several trends in the areas of data
processing and communications are
becoming more pronounced.
This evolution has created seriousproblems for network managers, it has
also resulted in the realization of the
necessity for network management
standards.
Northwestern Polytechnic University
36
Standards develop history
Beginning stages: 1980s
SGMP - RFC1028 - to manage routers
HEMS - RFC1021, 1022, 1023 and 1024
CMIP
RFC1065, RFC1066, RFC1067, RFC1095
-
8/10/2019 Network Management week#1
7/23
7
Northwestern Polytechnic University
37
Standards develop history
Growth and Progress: Early 1990s
RMON
UDP, OSI, IETF
SNMP began its integration into various
networks.
Northwestern Polytechnic University
38
Standards develop history
Moving toward the future: Mid- to Late
1990s
SNMPv2c: community-based.
SNMPv2u: user-based security.
SNMPv3: concurrent security and scalability
standardization.
RMON2: introduce the Meter MIB for traffic-
flow measurement.
RSVP: Resource Reservation Protocol
Northwestern Polytechnic University
39
Standards develop history
Moving toward the future: Mid- to Late
1990s
AgentX: SNMP agent extensibility Protocol
Master agents and subagents.
IPv6 MIB for TCP, UDP and ICMP.
MIB modules for ATM, DS1, E1, DS2, E2
Northwestern Polytechnic University
40
Northwestern Polytechnic University
41
Northwestern Polytechnic University
42
Comparison: OSIMAN, SNMP, TMN
Parent and superset of SNMP
Huge and complex
High development overhead and resourceusage
Inconvenient for small, simple devices
Designed (and used) for medium and large
networks
Network elements talk with management
system
OSIMAN:
-
8/10/2019 Network Management week#1
8/23
8
Northwestern Polytechnic University
43
Comparison: OSIMAN, SNMP, TMN
Simple and easy to use
Very good for small devices
Subset of OSIMAN
Has serveral shortcomings that some-times
make life hard (esp. In larger networks)
Lack of proper security
Inconvenient notification mechanism, etc.
Based on device polling
SNMP:
Northwestern Polytechnic University
44
Comparison: OSIMAN, SNMP, TMN
Huge framework that is based on OSIMAN but
can also utilize SNMP
Designed for large carrier networks
Management information is separated from
user data
Use of own network or protocol overhead
Integrates higher levels of management
Service views, billing, etc.
The TMN:
Northwestern Polytechnic University
45
Typical Use of Standards
LANs and end systems
practically SNMP only
WANs
IP devices (routers, etc.) SNMP only
ATM and FrameRelay switches SNMP in smaller systems and networks
OSIMAN for larger systems
integration into TMN in progress
Northwestern Polytechnic University
46
Typical Use of Standards
WANs (continued)
carrier infrastructures (SDH, PDH, lineswitches, WDM, microwave systems,etc.)
some SNMP for smallest systems when notinstalled in a carrier network
examples: HDSL modems, Laserlink devices
bulk is OSIMAN-based TMN
and beware:
most TMN systems support SNMP
Northwestern Polytechnic University
47
Northwestern Polytechnic University
48
IEEE Management
IEEE developed the first
management standard in 1982/83
for LANs only
Layer 2 protocol
not useable across routers
primarily used for IBM LANs
large Token Rings with bridges
died in the middle of the 80s
-
8/10/2019 Network Management week#1
9/23
9
Northwestern Polytechnic University
49
Common Concepts
OSIMAN and SNMP basically share
the same terminology and
mechanisms
see history
management frameworks are divided
into two parts
information model
communication model
Northwestern Polytechnic University
50
Information Model Basics
What do we want to manage?
network resources
How do we want to manage them?
by a computer application
So we need a model of the network
resources that is suitable for a
computer application.
Northwestern Polytechnic University
51
Information Model Basics
What is interesting?
resource type (class)
e.g. network interface
things that are special about this resource
e.g. Ethernet or Token Ring
current parameters in use
current state
last state
performance data
Northwestern Polytechnic University
52
Information Level
router or printer is difficult to
represent
we have to go down to basic data types
Integer, Character String, etc.
network address, byte counter
a surrounding structure is needed
to which element does this information
belong? (lots of detail information)
relationship to other data
Northwestern Polytechnic University
53
Management Information Tree
as usual, we choose a tree structure
Management Information Tree (MIT)
MIT follows the hierarchies in the
network an in the network elements
example: network -> subnet ->
computer -> interfaces -> ethernet
interface 1 -> bytesOut (an Integer)
Northwestern Polytechnic University
54
MIT: Small Example
Network
Subnet 1
BytesIn BytesOut
Ethernet 1
Status
Ethernet 2
Computer 2 Computer 3
Subnet 2Subnet 3
Computer 1
-
8/10/2019 Network Management week#1
10/23
10
Northwestern Polytechnic University
55
Management Information Tree
MIT models a whole network MIT data represents network state at the moment of
the MITs creation
MIT subtree in each network element is
called Management Information Base
(MIB) MIBs can be divided into functional parts that are
called MIBs also
full MIT is created by the management application
Northwestern Polytechnic University
56
Communication Model Basics
management application needs access toMIB data
we need a way to address data in the MIB
path through the tree structure
we need a service and a protocol to transport
management data
so we also need a transport encoding
and we need two instances that
communicate
Manager and Agent
Northwestern Polytechnic University
57
Communication Model Basics
Management
ApplicationsManager Agent
Resources
MIT/MIB
Manager
on the side of the
management application
Agent
on the side of the MIB (in
the network element)
Northwestern Polytechnic University
58
Properties of a Manager
Interface between the management
applications and the network elements
coordinates management applications
accesses agents to receive management
information
is informed by the agents if something has
happened (good or bad)
usually one manager per network
Northwestern Polytechnic University
59
Properties of an Agent
Answers requests of managers
Informs managers (notifications, alarms)
Access to resources Translation of a resource state into the
information model (transfer encoding)
Change of resource state and configuration by
request of a manager
Usually a piece of software that runs on
each network element
Northwestern Polytechnic University
60
Transfer Encoding
Managers and agents (should) not need to
run on the same platform So we have to use a platform-independent
encoding
Choice: ASN.1 Abstract syntax notation one (X.680 ff.)
Data is transferred together with syntax information
Allows usual data types and simple data structures
(but can get quite complex)
-
8/10/2019 Network Management week#1
11/23
11
Northwestern Polytechnic University
61
Transfer Encoding
So we can transfer syntax and values
But we still cannot transfer semantics
The information in a MIB cannot change its
semantics during run-time
A formal mechanism to describe the
semantics of management information is
still missing
The are some suggestions
Research subject
Northwestern Polytechnic University
62
Transfer Encoding
Semantics are described informally
by texts in the ASN.1 MIB definitions
Interpreted and implemented by
humans
Can be interpreted differently or simply
be misunderstood
Descriptions can get quite long
Northwestern Polytechnic University
63
CS 565 Network Management
Dr. Qingsong Zhang
3. OSI Management
Northwestern Polytechnic University
64
The OSI Standard Framework
Basic standard is ISO 7498-4 / ITU-T X.700
OSI basic reference model part 4: management
framework
Describes whole framework
OSI functional areas (see chapter 1)
ISO 10040 / ITU-t x.701 management
overview
Gives some additional information and clarifications
Northwestern Polytechnic University
65
OSI Information Model
ISO/ITU-Standard Structure of
Management Information (SMI)
ISO 10165 / ITU-T X.720 and X.721
Object-oriented model
Managed Objects (MOs)
each MO is an instance of a MO class
all usual OO mechanisms supported
(multiple) inheritance, polymorphism, etc.
Northwestern Polytechnic University
66
OSI Management Objects
each class consists of the following:
attributes (the management information)
at least one
accessed by the manager and monitored by the
agent
simple data types (Integer, Real, Boolean, and
Octet String; only constructor is SET OF)
access rights can be defined
a list of search functions that are allowed can be
given (see below)
semantics description by simple text
-
8/10/2019 Network Management week#1
12/23
12
Northwestern Polytechnic University
67
OSI Managed Objects
class contents (continued)
functions
parameters (attributes and simple types)
called by the manager
notifications
sent out to the manager(s) by the agent
have attributes as parameters
can be coupled with filter functions
set by the manager
for example to mask out certain alarms
Northwestern Polytechnic University
68
OSI Management Objects
class definition (in ASN.1)
use of class templates
inheritance from super classes
(only) addition of attributes, functionsand notifications
grouping of attributes, functions andnotifications into packages
only a whole package can be marked asoptional
Northwestern Polytechnic University
69
OSI Management Objects
Class definition and additional rules
and suggestions are described in
another standard
Guidelines for the Definition of
Managed Objects (GDMO)
usually this term is used instead of SMI
ISO 10165-4 / ITU-T X.722
integral part of the SMI
Northwestern Polytechnic University
70
OSI Management Objects
Class registration
Two hierarchies
Hierarchy one: the inheritance tree
Represents inheritance structure
Hierarchy two: the ISO registration tree
Defined in ASN.1
Each class has an object ID (OID) in theISO/ITU management classes subtree
Northwestern Polytechnic University
71
Class Hierarchies
Top
Class 1 Class 2
Subclass 1 Subclass 2
Subclass 2.1 Subclass 2.2
Root
ISO ITU ISO/ITU
Mgmt
Classes
Top Class 2 Subcl. 2.1
Registration as OIDInheritance Hierarchy
Northwestern Polytechnic University
72
The OSI Containment Tree
Mos are instances of MO classes
Multiple instances can exist anywhere in the MIT
MIT is called "Containment Tree" in this case
So we need an additional mechanism to address aMO
Path through the tree of MOs
Each MO has to have a name that is unique on the samelevel of a subtree
One attribute is selected for naming
The "Relative Distinguished Name" (RDN)
-
8/10/2019 Network Management week#1
13/23
13
Northwestern Polytechnic University
73
The OSI Containment Tree
The "distinguished Name" (DN) is the path
through the Containment Tree of a
network element
Consists of a concatenation of all RDNs along
the path beginning from the root
Similar to a absolute path name in UNIX
Used to address an object
This is quite similar to X.500
The ITU distributed directory service
Northwestern Polytechnic University
74
OSI Containment Tree Example
DN:
Name="npu1"
Type="Ethernet"
ID="0"
Name="ByteOut"
SystemName="npu1"
InterfaceType="Loopback"
InterfaceType="Ethernet"
EthernetID="0"
EthernetID="1"
CounterName="ByteIn"
CounterName="ByteOut"
Northwestern Polytechnic University
75
OSI communication Model
Common Management Information Service
(CMIS)
ISO 9595 / ITU-T X.710
Uses the Common Management Information
Protocol (CMIP)
ISO 9596 / ITU-T X.711 and X.712
Based on ACSE and ROSE
ACSE for access control
Every management operation is basically a remote
procedure call using ROSE
Northwestern Polytechnic University
76
OSI CMIS
Defines 8 basic operations:
M-GET
Manager requests attribute values
Agent answers with a M-RESPONSE
M-CANCEL-GET
Manager cancels a GET-request
M-SET
Manager changes attribute values
M-ACTION
Manager calls a function of a MO
Northwestern Polytechnic University
77
The OSI CMIS
Basic operations (continued)
M-CREATE
Manager dynamically creates a MO
i.e. the MIB changes during run-time
M-DELETE
Manager deletes a MO
M-EVENT-REPORT
Agents sends a notification of a MO
Notification must have passed the filter function
Northwestern Polytechnic University
78
CMIS Filter Functions
Manager can use a "search function"
No need to specify the DN of a certain MO
Each request can be sent out with a filter
function
Evaluated by the agent
Filters out attribute values
Every attribute for which the search function is
allowed and the filter matches is sent back
Manager can cancel a running request
M-CANCEL-GET
-
8/10/2019 Network Management week#1
14/23
14
Northwestern Polytechnic University
79
CMIS Filter Functions
Filter can be focused on a subtree
Scoping
Filters can be concatenated with logical
operations
Agent can reject a filter that is too
complicated for him to handle
Everything very similar to X.500
But no support for distributed MIBs
Northwestern Polytechnic University
80
Systems Management Functions
High-level functions for managementoperation
Based on the basic functions
Usually management applications usethe SMFs and do not directly access theCMIS
Defined in ISO 10164 (part 1-14) andITU-T X.730-X.742
Some additional function by ISO only
Northwestern Polytechnic University
81
Systems Management Functions
Management
Application
Management
Application
Management
Application
Accounting
Meter
Workload
Monitoring
Test
ManagementSummarization
Log
Control
Security
Alarm Report
Security
Audit Trail
Access
Control
Object
Management
State
Management
Relationship
Management
Alarm
Reporting
Event Report
Management
Event Report Get Set Action
Create Delete Cancel-Get
CMIS
SystemManagementFunctions
Northwestern Polytechnic University
82
OSIMAN Operation
Agents talk to manager
Only some availability polling
During normal operation
Network elements report events immediately
Very convenient for large networks
No careful selection of MOs
How many MOs can I poll how often before I
completely flood my network with management
information?
But we need quite powerful NEs
Northwestern Polytechnic University
83
OSI Management Functional Areas
Fault/Problem Management Detection, localisation, and repair of the fault
Configuration/Name Management
configuration and monitoring of resources fornormal operation
Performance/Growth Management performance measurements and comparison with
expected values
detect approaching problems and configuration
mistakes
network simulation (!) Northwestern Polytechnic University84
OSI Management Functional Areas
Accounting/Cost Management logging and export of data for bill ing
supervision of service access
most important in carrier networks
but will become a subject in corporate networksalso (for QoS issues)
a real challenge: its not easy
most companies have to throw quite a lot of moneyinto this to get it working
example: 75% of EWSD software is accounting
-
8/10/2019 Network Management week#1
15/23
-
8/10/2019 Network Management week#1
16/23
16
Northwestern Polytechnic University
91
Other Network Management Functions
Planning/Support Management
Enable network managers and
administrators to provide support for
current users, as well as plans for the
future.
Trend Analysis: Provides information
necessary for determining utilization
trends on both local and wide area
networks
Planning management processNorthwestern Polytechnic University
92
Summary
Network status
monitoring
Network Routing
Parameter
database
Configuration
control
Facility control
Configuration/
Change
Management
Event notification
Logging
Ticketing
Tracking
Isolation
Resolution
Fault/
Problem
Management
Monitoring
Statistical
analysis
Database
generation
and analysis
Reporting
Tuning
Performance/
Growth
Management
Authentication
of users
Maintaining
security
Encryption
Key Distribution
Audits
Traces
Security/
Access
Management
Issue orders
Recording
Reconciliation
of cost
algorithms
Assignment
of costs
Accounting
Cost
Management
Equipment
records
Facility
records
Personnel
records
Training
Asset
Management
Data collection
Requirements
analysis
Trend analysis
Modeling
Design
Optimization
Implementation
Planning
Support
Management
Network Management Functional Areas and Tasks
Northwestern Polytechnic University
93
Network Management Systems
Collection of tools for network
monitoring and control.
Designed to view the entire network
as a unified architecture, with
address and labels assigned to each
point and the specific attributes of
each element and link known to the
system.
Northwestern Polytechnic University
94
Network Management Configuration
Network control
host (manager)
NMA
NME Appl
Comm
OS
NME Appl
NME Appl
Comm
Comm
OS
OS
NME
Comm
OS
Workstation
(agent)
Server
(agent)
Router
(agent)
NMA = Network Management Applicat ion
NME = Network Management Ent ity
APPl = Applica tion
Comm = communicat ion sof twareOS = operating system
Elements of
a network management system
Northwestern Polytechnic University
95
Network Management Software Architecture
Presentationof network management
informationto users
Network
management
application
Network
management
application
application
element
Network management data transport service
MIB
access
module
Communications
protocol
stack
application
element
application
element
Managed networksManagement
information
base
Unified
user
interface
User Presentation
Network Management
Communication
Database
Northwestern Polytechnic University
96
Network Management Software Architecture
Presentationof network management
informationto users
Network
management
application
Network
management
application
application
element
Network management data transport service
MIB
access
module
Communications
protocol
stack
application
element
application
element
Managed networksManagement
information
base
Unified
user
interface
User Presentation
Network Management
Communication
Database
-
8/10/2019 Network Management week#1
17/23
17
Northwestern Polytechnic University
97
Distributed Network Management
Management server
Management
application MIB
Management server
Management
application MIB
Element
manager
Element
manager
Network
Network
Management
clients
Network resources
with management agents
Management
clients
Management
clients
Management
clients
Management
clients
Northwestern Polytechnic University
98
Proxies
Management
applicationProxy manager
Server
stub
Client proxy
stub
Protocol
stack
Server proxy
stub
Proprietary management
interface
Client
stub
Protocol
stack
Protocol
stack
Protocol
stack
Standard operations
and event reports
Proprietary operations
and event reports
Northwestern Polytechnic University
99
Network Management
Network Monitoring
Architecture
Performance
Fault
Accounting
Network Control
Configuration
SecurityNorthwestern Polytechnic University
100
Network Monitoring
Consists of three major design areas: Access to monit ored inform atio n: how to define
monitoring information, and how to get that
information from a resource to a manager.
Design of monitoring mechanisms: how best to
obtain information from resources.
App lic ation o f moni tor ed i nfo rmatio n: how the
monitored information is used in various
management functional areas.
Northwestern Polytechnic University
101
Architecture
Information Static
Dynamic
Statistical
Configuration Application
Manager
Agent
Object
Polling and event reporting
Northwestern Polytechnic University
102
Architecture
Organization of MIBStatistical
database
Dynamic
database
Static
database
Call_blocked Packet_Loss
Time_Delay Throughput
State_Variable
Event_Variable
Switch_Server
Buffer Source
Station_Info Server
Switch_Buffer
Switch_Source
Status_Sensor
Derived_Status_Sensor
Event_Sensor
Configuration Database
Sensor Database
-
8/10/2019 Network Management week#1
18/23
18
Northwestern Polytechnic University
103
Network-Monitoring Configurations
Monitoring
application
Manager
function
Agent
function
Managed
objects
Monitoring agent
Agent
function
Agent
function
Managed
objects
Managed
objects
Monitoring
application
Manager
function
. . .
(a) Manager-agent model
(b) A model for summarization
Northwestern Polytechnic University
104
Polling and Event Reporting
Polling: Manager queries any
authorized agents and requests the
values of various information
elements.
Reporting: Manager, as a listener,
waits for incoming information.
A network-monitoring system will
typically employ both methods.
Northwestern Polytechnic University
105
Polling and Event Reporting
Telecommunications Management
Systems (TMN) have traditionally
placed a very high reliance on event
reporting.
SNMP approach puts very little
reliance on event reporting.
OSI system management (OSIMAN)
tends to fall somewhere between
these extremes.Northwestern Polytechnic University
106
Performance Monitoring
Indicators One of the difficulties facing the network
manager is in the selection and use of the
appropriate indicators that measure the
networks performance.
Service-oriented measures
Specified service levels are maintained to the
satisfaction of the users.
Efficient-oriented measures
Meeting these requirements at minimum cost.
Northwestern Polytechnic University
107
Performance indicators
Service-oriented
Availability The percentage of time that a network system, a component,or an application is available for a user.
Response
time
How long it takes for a response to appear at a users
terminal after a user action calls for it.
Accuracy The percentage of time that no errors occur in thetransmission and delivery of information
Efficiency-oriented
Throughput The rate at which application-oriented events (e.g.transaction messages, file transfers) occur.
Utilization The percentage of the theoretical capacity of a resource (e.g.multiplexer, transmission line, sw itch) that is b eing used.
Northwestern Polytechnic University
108
Indicators
Availability The percentage of time that a network
system, component, or application is
available.
MTBF
MTBF + MTTRA =
A the availability
MTBF the mean time between failures
MTTR the mean time to repair
-
8/10/2019 Network Management week#1
19/23
19
Northwestern Polytechnic University
109
Configuration effects on the availability
A A
A
A(a) Serial
(b) Parallel
(A2)
(2A-A2)
The availability of a system depends on the availability of its
individual components plus the system organization.
Northwestern Polytechnic University
110
Response Time
Is the time it takes a system to a given
input.
Ideally, one would like the response time
to be short, which possibly imposes
greater cost.
Computer processing power
Competing requirements
The value of a given level of response time
must be assessed versus the cost of
achieving that response time.
Northwestern Polytechnic University
111
Element of Response Time
Workstation Network interface
(e.g. bridge)
ServerTO
TIWI
SI
SO
WOCPU
RT = response time
TI = inbound terminal delay
WI = inbound queuing time
SI = inbound service time
CPU = CPU processor delay
WO = outbound queuing time
SO = outbound service time
TO = outbound terminal delay
RT = TI + WI + SI + CPU + WO + SO + TO
Northwestern Polytechnic University
112
Accuracy, Throughput and Utilization
Accuracy: Indication of faulty line,
noise and interference.
Throughput: Projected demand and
likely performance trouble spots.
Utilization: the percentage of time
that a resource is in use over a given
period of time.
Northwestern Polytechnic University
113
Performance-Monitoring Function
Three components
Performance measurement
Performance analysis
Synthetic traffic generation
Typical Performance Measurement Reports
(detailed on P. 39 of text book)
Host communication matrix
Group communication matrix
Packet type histogram
Data packet size histogram
Throughput-utilization distribution
Packet interarrival time histogram
Channel acquisition delay histogram
Communication delay histogram
Collision count histogram
Transmission count histogram
Northwestern Polytechnic University
114
Statistical Versus Exhaustive Measurement
When an agent in a node or an
external monitor is monitoring a
heavy load, it may not be pratical to
collect exhaustive data. The alternative is to treat each
parameter as a random variable and
sample the traffic stream in order to
estimate the value of the random
variable.
-
8/10/2019 Network Management week#1
20/23
20
Northwestern Polytechnic University
115
Fault Monitoring
The objective is to identify faults as
quickly as possible after they occur
and to identify the cause of the fault
so that remedial action may be taken.
Problems of Fault Monitoring:
Unobservalbe faults
Partially observable faults
Uncertainty in observation
Multiple potential causes
Too many related observtions
Interference between diagnosis and local
recovery procedures
Absence of automated testing tools
Northwestern Polytechnic University
116
Fault-Monitoring Functions
To detect and report faults.
To report errors independently to
one or more managers.
To anticipate faults.
To isolate and diagnose the fault.
Northwestern Polytechnic University
117
Accounting Monitor
To track users usage of network
resources.
To gather and maintain following
accounting data:
User identification
Receiver
Number of packets
Security level
Time stamps
Network status codes
Resources used:
Northwestern Polytechnic University
118
Summary
The purpose of network monitoring is
to gather information about the status
and behavior of network elements.
Information to be gathered:
Static - configuration
Dynamic - events in the network
Statistical - summarization from dynamic
info.
Northwestern Polytechnic University
119
Summary
Information may be collected actively, by
means of polling by the management
station, or passively, by means of event
reporting by the agents. The most important categories of
management information are
Availability
Response time
Accuracy
Throughput
Utilization
Northwestern Polytechnic University
120
Network Control
To modify parameters, or configurations.
Mainly cover the last two major function
areas of network management:
Configuration management
Security management
-
8/10/2019 Network Management week#1
21/23
21
Northwestern Polytechnic University
121
Configuration Control
Covers initialization, maintenance and
shutdown of individual components and
logical subsystems within the total
configuration of computer and
communications resources of an installation.
Responsible for monitoring the configuration
and making changes in response to user
commands or other network management
functions.
Northwestern Polytechnic University
122
Functions of Configuration Management
Define configuration information
Set and modify attribute values
Define and modify relationships
Initialize and terminate network operations
Distribute software
Examine values and relationships
Report on configuration status
Configuration-Control Configuration-Monitor
Northwestern Polytechnic University
123
Define Configuration Information
Describes the nature and status of
resources of managed network.
Includes
Resources
Physical (end systems, routers, bridges and
communications media and service)
Logical (timers, counters and virtual circuits)
Attributes
Name, address, ID, states, operational
characteristics, software version number, etc.)
Northwestern Polytechnic University
124
Set and Modify Attribute Vaules
Must be authorized.
Some attributes can not by modified
remotely.
Categories
Database update only
Database update + resource
modification
Database update + action
Northwestern Polytechnic University
125
Define and Modify relationships
Describes an association,
connection or condition that exists
between network resources or
network components. Should allow on-line modification of
resources without taking all or part
of the network down.
Northwestern Polytechnic University
126
Initialize and Terminate Network
Operations
Should include mechanisms to
enable users to initialize and close
down network or subnetwork
operation. Verification resources
Notification users
Validation
Retrieval of status information before
the termination.
-
8/10/2019 Network Management week#1
22/23
22
Northwestern Polytechnic University
127
Distribute Software
Synchronize the software on bothend systems and intermediatesystems.
Encompass tables and other datathat drive the behavior of a node.
Provide mechanisms to examine,update and manage different versionof software and routing information.
Northwestern Polytechnic University
128
Security Control
Computer Security
Network Security
The security management deals with
the provision of both computer and
network security for the managed
resources, including management
itself.
Northwestern Polytechnic University
129
Security Threats
Security requirements:
Secrecy
Integrity
Availability
Types of threats
Interruption
Interception
Modification
FabricationNorthwestern Polytechnic University
130
Computer System
Assets
Security Threats and Assets
Hardware Software
DataCommunication
Lines
modification
interception
(capture, analysis)
masquerade
interruption
(loss)
interruption
(theft, denial of service) interruption(deletion)interception
modification
modification
interception
(capture, analysis)
masquerade
interruption
(loss)
Northwestern Polytechnic University
131
Threats to Networks
Passive threats
Interception (secrecy)
Release of
message contentsTraffic analysis
Active threats
Interruption
(availability)
Modification
(integrity)
Fabrication
(integrity)
Northwestern Polytechnic University
132
Threats to the Network
Management System
User masquerade
Network manager masquerade
Interference with manager-agent
interchange
-
8/10/2019 Network Management week#1
23/23
Northwestern Polytechnic University
133
Security Management Functions
Maintain Security InformationSecure the information change between managersand agents.
Control Resource-Access Service
Access control involves authentication andauthorization services and decision to grant orrefuse access to the resources.
Control the Encryption Process
encrypt any exchanges between managers andagents, also design encryption algorithms andprovide key distribution.
Northwestern Polytechnic University
134
Summary
Network control is concerned with altering
parameters of various components of the
configuration and causing predefined
actions to be preformed by these
components.
The responsibility of the network
management system is to coordinate and
control the security mechanisms built into
the configuration of networks and
systems under its management control.