FACULTY
OF INFORMATICS
Masaryk University
PA160: Net-Centric Computing II. Network Management
Luděk Matýska Slides by: TomasRebok
Spring 2023
Luděk Matýska • Network Management • Spring 2023
Lecture overview
FACULTY
OF INFORMATICS
I   Masaryk University
Lecture overview
Motivation
Network Management
Network Management by ISO
Basic Network Management Components Network Elements Management Systems Management Network Management Support Organization Basic Components Refined
Simple Network Management Protocol (SNMP) Structure of Management Information Management Information Base (MIB) Simple Network Management Protocol (SNMP)
Conclusion
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Motivation
FACULTY
OF INFORMATICS
Masaryk University
Lecture overview
Motivation
Network Management by ISO
Network Elements Management Systems Management Network Management Support Organization Basic Components Refined
Structure of Management Information
Management Information Base (MIB)
Simple Network Management Protocol (SNMP)
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Motivation
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The Case for Management I.
typical problem
■ remote user arrives at regional office and experiences slow or no response from corporate web server
Where should we begin?
■ Where is the problem?
■ What is the problem?
■ What is the solution?
without proper network management, these questions are difficult to answer
Regional Offices
VP
1	
	7Ü5
T~ \_WWW Servers
Corp Network
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Motivation
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The Case for Management II.
■ with proper management procedures and tools, one may "easily" get the answer
■ consider some possibilities:
■ What configuration changes were made overnight?
■ Have you received a device fault notification indicating the issue?
■ Have you detected a security breach?
■ Has your performance baseline predicted this behavior on an increasingly congested network link?
Ludek Matyska • Network Management • Spring 2023
^ 'I ---'BÖH
>hü—ESI
WWW Sen
Corp Network
Motivation
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The Case for Management III.
A bit of history
■ during the old days, a network could be managed using human efforts only
■ in a smaLL system, running few "p/ngs"may help Locating the problem
■ 27.10.1980: first real (ARPANET) network crash
■ described in RFC 789
■ including the steps performed for the recovery
■ further experiences obtained on similar cases
■ e.g., a "worm" in 1988
■ as the Internet becomes a large global infrastructure, automated
network management and monitoring tools are essential
■ standardized tools that can be used across a broad spectrum of product types are also needed (heterogenous equipment)
■ =^ Network Management =^ Network Management System (NMS)
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Motivation
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The Case for Management IV.
What should be monitored?
What should be monitored?
■ basic network elements
■ network interfaces - e.g., an increase in checksum errors in frames sent out by the interface
■ network components - servers, routers, end-hosts, etc.
■ physical links
■ traffic monitoring - by Link utilization monitoring, system bottlenecks may be determined (and solved)
■ routing information - e.g., rapid changes in routing tables
■ a compliance with SLAs (Service Level Agreements)
■ suspicious behavior - security attacks, patterns indicating suspicious traffic, etc.
■ etc.
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Network Management
FACULTY
OF INFORMATICS
I   Masaryk University
Lecture overview
Network Management
Network Management by ISO
Network Elements Management Systems Management Network Management Support Organization Basic Components Refined
Structure of Management Information
Management Information Base (MIB)
Simple Network Management Protocol (SNMP)
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Network Management
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Network Management
■ the process of controlling a complex data network
■ controlling = monitoring, testing, configuring, and troubleshooting
■ the overall goal is to help with the complexity of the network and to ensure that data can go across it with maximum efficiency and transparency to the users
Network Management
Network management includes the deployment, integration and coordination of the hardware, software, and human elements to monitor, test, poll, configure, analyze, evaluate, and control the network and element resources to meet the real-time, operational performance, and Quality of Service requirements at a reasonable cost.
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Network Management
Network Management by ISO
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Masaryk University
Network Management by ISO
■ ISO (International Organization for Standardization) has created a network
management model (often referred as FCAPS model):
■ Fault management
■ Configuration management
■ Accounting management
■ Performance management
■ Security management
this classification has gained broad acceptance by vendors of both
standardized and proprietary NMSs
■ the model does not define the actual implementation of a NMS
Functions of a network management system
Configuration management
Fault
management
■ Reconfiguration ■Documentation
Performance management
— Reactive —Capacity
1— Proactive — Traffic
—Throughput
Ludek Matyska • Network Management • Spring 202§esPonsetime
Security management
Accounting management
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Network Management     Network Management by ISO
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Network Management by ISO
■ a fault = an abnormal condition that requires management attention (or action) to repair
Fault management:
■ the facilities that enable the detection, isolation, and correction of abnormal
operation of the network
■ deals with both HW & SW failures
■ includes logging the detected information
■ two variants:
■ Reactive Fault Management - reacts to incurred errors; involves the
following steps:
■ discovering the problem
■ isolating the problem
■ fixing the problem (if possible)
■ and documenting the problem
■ Proactive Fault Management - tries to prevent faults from occurring
■ provides alarms - unsolicited messages indicating that some unexpected event has occurred in the network (link down, intrusion detected, etc.)
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Network Management     Network Management by ISO
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Network Management by ISO
Configuration management:
■ includes functionality to perform operations that will deliver and modify
configuration settings to equipment in the network
■ includes the initial configuration of a device to bring it up as well as ongoing configuration changes
■ includes both HW & SW configurations
■ includes (HW & SW) documentation as well
■ functions:
■ configuring Managed Resources
■ auditing the network and discovery what's in it
■ synchronization management information in the network
■ backing up network configuration and restoring
■ managing software images running on network equipment
■ steps:
1. gather information about current network, maintain an up-to-date inventory of all network components
2. (if necessary) use that data to modify the configuration of the network devices (= reconfiguration)
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Network Management
Network Management by ISO
FACULTY
OF INFORMATICS
I   Masaryk University
Network Management by ISO
Accounting management:
■ concerned with tracking network utilization information, such that individual users, departments, or business units can be appropriately billed or charged for accounting purposes
■ but does not serve for charging purposes only - tracking network utilization information can be also used for:
■ detecting users that are abusing their access privileges and burdening the network at the expense of other users
■ detecting users making inefficient use of the network (network managers can assist in changing procedures to improve performance)
■ network managers to plan the network growth (easier when end user activity is known in sufficient detail)
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Network Management
Network Management by ISO
FACULTY
OF INFORMATICS
I   Masaryk University
Network Management by ISO
Performance management:
■ involves measuring the performance of the network hardware, software, and media
■ e.g., overall throughput, percentage utilization, error rates, response time, etc.
■ measures both individual and complex components (e.g., an end-to-end path)
■ tries to monitor and control the network to ensure that it is running as
efficiently as possible
■ closely related to fault management (but considers long-term behavior)
■ functional categories:
■ Monitoring - ability to monitor and track activities on the network
■ Controlling - ability to make adjustments to improve network performance
■ performance statistics can help managers to:
■ plan, manage and maintain large networks
■ recognize potential bottlenecks in advance
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Network Management
Network Management by ISO
FACULTY
OF INFORMATICS
Masaryk University
Network Management by ISO
Security management:
■ responsible for controlling access to the network based on a predefined policy
■ requires identifying the sensitive information (e.g., network management information), which should be protected
■ provides audit trails and sounds alarms for security breaches
■ not only concerned with ensuring that a network environment is secure, but also that gathered security-related information is analyzed regularly
■ includes network authentication, authorization, and auditing
■ together with firewalls and IDSs
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Basic Network Management Components
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Masaryk University
Lecture overview
Network Management by ISO
Basic Network Management Components Network Elements Management Systems Management Network Management Support Organization Basic Components Refined
Structure of Management Information
Management Information Base (MIB)
Simple Network Management Protocol (SNMP)
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Basic Network Management Components
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Basic Components of Network Management Systems
Management Support Organization	1 I1 f	an*?
A T		
Management Systems
t
-^  i —
Management Network
A v
Network Devices
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Basic Network Management Components
Network Elements
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Network Elements (NEs) I.
Network Devices —>► Network Elements (NEs)
■ to be managed, every NE must offer a management interface through which a managing system can communicate with it
■ receives requests and responses to them
■ sends unsolicited information, when an unexpected event has occurred (e.g., failure of a fan or a buffer overflow)
■ a managing application = manager, the network element = agent
Manager
("client")
Requests
Responses+ Events
Managed System
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Basic Network Management Components
Network Elements
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Network Elements (NEs) II.
Management Agents I.
NEs have to provide a piece of software that implements the management interface
■ = Management Agent
■ "agent" becomes overloaded
■ agent = the role that a network element plays in network management
■ agent = software component that allows the network element to play that role (provides the management interface)
■ management agent's functionality:
■ collects statistics (stores them locally)
■ responds to manager's commands, e.g.:
■ sends the collected statistics
■ provides/changes the node's parameters
■ provides status information
■ sends unsolicited messages for significant changes in local conditions
■ etc.
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Basic Network Management Components
Network Elements
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OF INFORMATICS
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Network Elements (NEs) II.
Management Agents II.
■ the (Management) Agent consists of three main parts:
■ management interface - handles management communication
■ supports a management protocol that defines the "rules of conversation"
■ Management Information Base (MIB) - a conceptual data store that contains a management view of the device being managed
■ a way to view the device itself, not a database in which information about the device is stored
■ constitutes the management information (provides an abstraction of real-world aspects (= managed objects) for management purposes)
■ core agent logic - translates between the operation of the management interface, the MIB, and the actual device
e.g., translates the request "retrieve a counter" (referred to in the MIB) into an internal operation that reads out a device hardware register containing the desired information
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Basic Network Management Components
Network Elements
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Network Elements (NEs) II.
Management Agents III.
Managing System "Manager"			
i		manages	
Managed System "Agent"	Management Interface		Management Agent
	Embedded Core J Management j Agent Intelligence Logic		MIB A
	-i	c--1 interacts with represents r 1	
	Real Resource (device, operating system...)		
Figure: Anatomy of a Management Agent.
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Basic Network Management Components
Network Elements
FACULTY
OF INFORMATICS
Masaryk University
Network Elements (NEs) II.
Management Agents IV.
Management Agents cont'd.
■ a single network element can contain several management agents
managing the same objects
■ each of which with its own management interface
■ reasons: e.g., to give management applications a choice of management interfaces or different management agents might each serve different functions
Agent Dale
"Dog"
Agent Jacques
Chien"
Agent		"Hund"
Friedrich		
Managed System
Real
Resource
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Basic Network Management Components     Management Systems
FACULTY
OF INFORMATICS
Masaryk University
(Network) Management System (NMS) I.
Network Management System (NMS)
■ a collection of tools for network monitoring and control
■ designed to view the entire network as a unified architecture
■ providing an interface with a powerful but user-friendly set of commands
■ the network active elements provide regular feedback of status information
to the network control center(s)
■ one or more network control centers can be used
■ centralized vs. hierarchicalvs. distributed layout
Paradoxical situation:
■ to work properly, a NMS needs a network that works properly so that
management applications and managed network can talk to each other
■ without this, it would be impossible to exchange management commands and management information
■ of course, for the network to work properly, a proper NMS needs to be employed
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Basic Network Management Components     Management Systems
FACULTY
OF INFORMATICS
Masaryk University
(Network) Management System (NMS) II.
Centralized Layout
■ the NMS resides on a single computer system
■ may be backed up by another system for High Availability purposes
■ but may reside on multiple computer systems as well
e.g., to distribute the load - one center is idle or collecting statistics, while the other is used for control
managing entity
managing entity
network management protocol
managed device
managed device Luděk Matýska • Network Management • Spring 2023
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Basic Network Management Components     Management Systems
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(Network) Management System (NMS) II.
Hierarchical Layout I.
■ the NMS resides on multiple management servers
■ one system acts as the central server
■ other systems working as clients = intermediate managers (management proxies)
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Basic Network Management Components     Management Systems
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OF INFORMATICS
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(Network) Management System (NMS) II.
Hierarchical Layout II. - Management Proxies
■ the systems that play both agent and manager roles simultaneously
■ the system plays the agent role in interacting with the NMS, but it plays the manager role in interacting with the other network element(s)
■ multiple levels of hierarchy are possible
Manager
A
Y
Agent
Manager A.
y
Agent
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Basic Network Management Components     Management Systems
FACULTY
OF INFORMATICS
Masaryk University
(Network) Management System (NMS) II.
Distributed Layout
■ combines the centralized and hierarchical architectures
■ the NMS uses multiple peer network management systems
■ each peer controls/monitors a part of the network
Management clients ( PCs, workstations )
Management server		
	Management	
	application	
Management server		
i	Management application	
Network resources ( servers, routers, hosts ) with management agents Ludek Matyska • Network Management • Spring 2023
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Basic Network Management Components
Management Network
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Management Network
■ managing systems and managed systems need to be interconnected
■ Management Network
■ a management network and a production network can:
■ be physically separate (dedicated) networks
■ serial interface (direct or through terminal servers)
■ network interface (Ethernet or any other dedicated network)
■ share the same physical network
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Basic Network Management Components
Management Network
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Management Network
Dedicated vs. Shared management and production networks I
Production Traffic Management Traffic
Production Network
(a) Shared Network for Management and Production Traffic
Ded icated
Management s-
^-^Network |
Production Network
(b) Dedicated Management Network
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Basic Network Management Components
Management Network
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Management Network
Advantages of dedicated management network:
■ Reliability - since the management traffic is carried independently of the production traffic, the management becomes significantly more reliable
■ e.g., network congestion/failure will not make a certain segment out of reach
■ Interference avoidance - the management traffic does not compete with other networking (production) traffic
■ important when high OoS requirements have to be satisfied in the production network
■ although management traffic is not very high in volume, it may be bursty and still of non-negligible volume
■ (it might involve downloading large files with new configurations or software images to network elements, etc.)
■ interference between management and production network traffic can also make certain problems harder to diagnose
■ Security - a dedicated mgmt network is harder to attack and easier to secure
■ less prone to hackers and less vulnerable to, e.g., DoS attacks on the production network
■ Ease of network planning - (production) network planning becomes easier if there is no need to consider management traffic
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Basic Network Management Components
Management Network
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Management Network
Disadvantages of dedicated management network:
■ Cost and overhead - a dedicated management network requires a separate network to be built
■ the dedicated network requires additional devices, additional space, and additional cabling
■ significant additional cost
■ No reasonable alternative - sometimes, a shared network might realistically be the only option
■ e.g., the equipment deployed at the customer side might be reachable only through one network (DSL lines, etc.)
Question: What about a management of the dedicated management network?
■ i.e., to have a "management management network"
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Basic Network Management Components
Management Support Organization
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Management Support Organization I.
Organizational (non-technical) aspects of network management, e.g.:
■ Establishment of process and operational policies, documentation of operational procedures
■ helps to make the management consistent and efficient
■ especially in cases of emergencies
■ may include:
■ weU-defined workflows to make sure that things that are supposed to happen do not fall through cracks
■ well-defined escalation procedures to ensure responsiveness
■ etc.
■ Collection of audit trails
■ automatic logging the activities of management support staff
■ who initiated what action, and at what time
■ makes it easier to reproduce what happened and how to recover from situations in which human error or omission led to operational failures
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Basic Network Management Components
Management Support Organization
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Management Support Organization II.
Organizational (n on-technical) aspects of network management cont'd.:
■ Network documentation
■ the network itself should be documented (and up-to-date\)
■ important for network planning
■ e.g., planning the SW updates
■ also enables to identify discrepancies between what is supposed to be in the network and what actually has been deployed
■ Reliable backup and restore procedures
■ allows to bring the network back up in case of disasters or emergencies
■ e.g., restoring the last configuration that was known to work properly
■ Security emphasis
■ the most significant threats to the network might be lead from disgruntled employees on the inside
■ employees have physical access to the network equipment
■ etc.
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Basic Network Management Components     Basic Components Refined
FACULTY
OF INFORMATICS
Masaryk University
Basic Components of Network Management Refined
Management Technology
Management	«9 f* »	Mé
Support	U U Í U	um
Organization	;/T;    \ / a iJ U it U	i   ; i   i / 12i U M C y li
Management Systems (User Proxies)
Management Protocols "Rules of Conversation"
Management Network
Management Agents (Real-World Proxies)
Real World
Production Network
User Concern
Network Devices
Figure: Basic Parts of the Network Management - Refined.
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Simple Network Management Protocol (SNMP)
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OF INFORMATICS
Masaryk University
Lecture overview
Network Management by ISO
Network Elements Management Systems Management Network Management Support Organization Basic Components Refined
Simple Network Management Protocol (SNMP)
Structure of Management Information
Management Information Base (MIB)
Simple Network Management Protocol (SNMP)
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Simple Network Management Protocol (SNMP)
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Network Management Protocol
Two competing standards:
■ OSI CMISE/CMIP (Common Management Service Element/Common Management Information Protocol)
m de jure standards derived from the OSI framework
■ implementation issues have limited its use
■ SNMP (Simple Network Management Protocol)
m de facto standards based on TCP/IP
■ both standards define, how multiple devices in a network can exchange messages for the purpose of network management
■ including what information can be passed between the devices for this purpose
■ at the present time, the SNMP is winning the battle
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Simple Network Management Protocol (SNMP)
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Simple Network Management Protocol (SNMP) I.
■ a tool (protocol) that allows for remote and Local management of items on the network including servers, workstations, routers, switches, and other managed devices ■ application-level "protocol"
■ more than a protocol    it's a framework consisting of a number of architectural components that define how management information is structured, stored, and how it is exchanged using the SNMP protocol itself
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Simple Network Management Protocol (SNMP)
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Simple Network Management Protocol (SNMP) II.
History
■ SNMP derived from its predecessor SGMP (Simple Gateway Monitoring Protocol) (RFC 1028)
■ SNMPvl (1988) - poor security (authentication only by a
"community string", transmitted in cLeartext)
■ SNMPv2 (1993) - improvements in the areas of performance, security, confidentiality, and manager-to-manager communications
■ several variants - SNMPv2c (community-based security), SNMPv2u (user-based security), and SNMPv2 (party-based security)
■ currently - SNMPv3 (1999)
■ makes no changes to the protocol aside from the addition of cryptographic security - encryption, message integrity, and authentication
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Simple Network Management Protocol (SNMP)
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Simple Network Management Protocol (SNMP) III.
■ uses the Manager-Agentapproach
■ proxy managers are also supported (from SNMPv2)
Agent variables
■ main SNMP advantages:
■ standardized
■ universally supported
■ extendible
■ portable
■ allows distributed management access
■ lightweight
■ both simple framework architecture & simple agent implementations on NEs
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Simple Network Management Protocol (SNMP)
FACULTY
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Masaryk University
Simple Network Management Protocol (SNMP)
Components
Management
role of SNMP:
■ defines the format of messages (packets) exchanged by management systems and agents
role of SMI (Structure of Management Information):
■ rules specifying the format used to define objects managed on the network that the SNMP protocol accesses
■ defines general rules for naming objects, defining object types (including range and length), and showing how to encode objects and values
role of MIBs (Management Information Bases):
■ collections of named objects, their types, and their relationships to each other in an entity to be managed
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Simple Network Management Protocol (SNMP)
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Simple Network Management Protocol (SNMP)
Components - A Computer Program Analogy
The task of network management may be compared to the task of writing a computer program:
■ before one writes a program, the syntax of the Language (such as C or Java) must be predefined
■ including the structure of variables (simple, structured, pointer, etc.) and how the variables must be named
■ in network management, these rules are defined by SMI
■ most computer Languages require variables to be declared in a program
■ the declaration names each variable and defines the predefined type
■ in network management, this is defined by MIB
■ MIB names each object and defines the type of the objects
■ the type is a type defined by SMI
■ once variabLes are decLared, the program needs to write statements to store values in the variabLes and change them if needed
■ in network management, this task is done by SNMP
■ it stores, changes, and interprets the values of objects already declared by MIB according to the rules defined by SMI
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Simple Network Management Protocol (SNMP)
FACULTY
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Simple Network Management Protocol (SNMP)
Overview
■ when a manager wants to send a message to an agent station to find the
number of UDP user datagrams received:
■ MIB is responsible for finding the object that holds the number of the UDP user datagrams received
■ SMI, with the help of another embedded protocol, is responsible for encoding the name of the object
■ SNMP is responsible for creating a message, called GetRequest, and encapsulating the encoded message
Number of UDP user datagrams?
MIB
The object has an integer value and is called udplnDatagram with id 1.3.6.1.2.1.7.1.0
Retrieve the value of an object with code 06 09..........
-| SNMP I
Encapsulate the request in a GetRequest message
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Simple Network Management Protocol (SNMP)
Structure of Management Information
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OF INFORMATICS
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Structure of Management Information (SMI)
Structure of Management Information (SMI)
■ currently version 2 (SMIv2)
■ functions:
■ to name objects
■ to define the type of data that can be stored in an object
■ to show how to encode data for transmissions over the network
	Object attributes		
			
			
Name	Type		Encoding method
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Simple Network Management Protocol (SNMP)
Structure of Management Information
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Structure of Management Information (SMIv2)
Naming objects I. - Object name
■ to name objects gLobaLLy, SMI uses an object identifier, which is a hierarchical identifier based on a tree structure
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Simple Network Management Protocol (SNMP)
Structure of Management Information
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Structure of Management Information (SMIv2)
Naming objects II.
■ = OlDs (Object IDentifiers)
■ each object can be defined using a sequence of integers separated by dots
■ e.g., 1.3.6.1.2.1
■ this representation is used by SNMP
■ or using a sequence of textual names separated by dots
■ e.g., iso.org.dod.internelmgmtmib-2 this representation is used by people
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Simple Network Management Protocol (SNMP)
Structure of Management Information
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Structure of Management Information (SMIv2)
Object type
■ the type of data stored in the object
■ to define the data type, SMI makes use of Abstract Syntax Notation 1 (ASN.l) definitions
■ and adds some new definitions
■ ASN.l - a standard and flexible notation that describes data structures for representing, encoding, transmitting, and decoding data
■ two categories of object types: simple and structured
■ structured data types created by: sequence and sequence ofoperators
■ sequence - a list of (arbitrary) data fields     a record/structure in computer programming)
■ sequence of - an array of data fields or records (sequences)
■ by a combination of simple and structured data types, new structured data types can be created
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Simple Network Management Protocol (SNMP)
Structure of Management Information
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Structure of Management Information (SMIv2)
Object type - Simple data types
Type	Size	Description
INTEGER	4 bytes	t l                n 1 An integer with a value between -2   and 2-1
Integers 2	4 bytes	Same as INTEGER
Unsigned32	4 bytes	Unsigned with a value between 0 and 232 - 1
OCTET STRING	Variable	Byte string up to 65,535 bytes long
OBJECT IDENTIFIER	Variable	An object identifier
IPAddress	4 bytes	An IP address made of four integers
Counter32	4 bytes	An integer whose value can be incremented from 0 to 2  ; when it reaches its maximum value, it wraps back to 0.
Counter64	8 bytes	644?it counter
Gauge32	4 bytes	Same as Counter32, but when it reaches its maximum value, it does not wrap; it remains there until it is reset
TimeTicks	4 bytes	A counting value that records time in ^ s
BITS		A string of bits
Opaque	Variable	Uninterpreted string
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Simple Network Management Protocol (SNMP)
Structure of Management Information
FACULTY
OF INFORMATICS
Masaryk University
Structure of Management Information (SMIv2)
Object type - Structured data types
a. Simple variable
		• • •	i
c. Sequence			
		• • #	
		• • •	
• • •			
		• • •	
b. Sequence of d. Sequence of
(simple variables) (sequences)
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Simple Network Management Protocol (SNMP)
Structure of Management Information
FACULTY
OF INFORMATICS
Masaryk University
Structure of Management Information (SMIv2)
Encoding method
Encoding method
■ the Basic Encoding Rules (BER) standard is used to encode data to be transmitted over the network
■ in order to be understood by both communicating parties uniformly
■ BER specifies that each piece of data can be encoded in triplet format: tag, length, and value
Tag
Length Value
Class 2 bits
Format 1 bit
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Simple Network Management Protocol (SNMP)
Structure of Management Information
FACULTY
OF INFORMATICS
I   Masaryk University
Structure of Management Information (SMIv2)
Encoding method - Tag I.
Encoding method - Tag
■ 1-byte field that defines the type of data
■ composed of three subfieLds:
■ class - universal (00), applicationwide (01), context-specific (10), or private (11)
■ universal - data types taken from ASN.l
■ applicationwide - data types added by SMI
■ context-specific - data types having the meanings that may change from one protocol to another
■ private - data types that are vendor-specific
■ format - simple (0) or structured (1)
■ number - further divides simple or structured data into subgroups
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Simple Network Management Protocol (SNMP)
Structure of Management Information
FACULTY
OF INFORMATICS
Masaryk University
Structure of Management Information (SMIv2)
Encoding method - Tag II.
Data Type	Class	Format	Number	Tag (Binary)	Tag (Hex)
INTEGER	00	0	00010	00000010	02
OCTET STRING	00	0	00100	00000100	04
OBJECT IDENTIFIER	00	0	00110	00000110	06
NULL	00	0	00101	00000101	05
Sequence,sequence of	00	1	10000	00110000	30
IPAddress	01	0	00000	01000000	40
Counter	01	0	00001	01000001	41
Gauge	01	0	00010	01000010	42
TimeTicks	01	0	00011	01000011	43
Opaque	01	0	00100	01000100	44
Luděk Matýska • Network Management • Spring 2023
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Simple Network Management Protocol (SNMP)
Structure of Management Information
FACULTY
OF INFORMATICS
Masaryk University
Structure of Management Information (SMIv2)
Encoding method - Length
Encoding method - Length
■ 1 or more bytes field
■ 1-byte    the most significant bit must be 0
■ the other 7 bits define the Length of the data
■ more-bytes    the most significant bit of the first byte must be 1
■ the other 7 bits of the first byte define the number of bytes needed to define the Length
0	0	0	0	0	0	1	0
a.The colored part defines the length (2).
1	0	0	0	0	0	1	0
0	0	0	0	0	0	0	1
0	0	0	0	0	1	0	0
b.The shaded part defines the length of the length (2 bytes); the colored bytes define the length (260 bytes).
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Simple Network Management Protocol (SNMP)
Structure of Management Information
FACULTY
OF INFORMATICS
I   Masaryk University
Structure of Management Information (SMIv2)
Encoding method - Examples I.
■ INTEGER with a value 14
02	04	00	00	00	0E
00000010	00000100	00000000	00000000	00000000	00001110
Tag (integer)	Length (4 bytes)		Value (14)		
■ OCTET STRING with a value "HI"
04	02	48	49
00000100	00000010	01001000	01001001
Tag	Length	Value	Value
(String)	(2 bytes)	(H)	(1)
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Simple Network Management Protocol (SNMP)
Structure of Management Information
FACULTY
OF INFORMATICS
I   Masaryk University
Structure of Management Information (SMIv2)
Encoding method - Examples II.
■ Objectldentifier with a value 1.3.6.1
06	04	01	03	06	01
00000110	00000100	00000001	00000011	00000110	00000001
Tag	Length	Value	Value	Value	Value
(Objectld)	(4 bytes)	(1)	(3)	(6)	(1)
1.3.6.1 (lso.org.dod.internet)-»*|
■ IPAddress with a value 131.21.14.8
40	04	83	15	OE	08
01000000	00000100	10000011	00010101	00001110	00001000
Tag Length Value Value Value Value
(IPAddress) (4 bytes) (131) (21) (14) (8)
U-131.21.14.8 -
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Simple Network Management Protocol (SNMP)
Structure of Management Information
FACULTY
OF INFORMATICS
Masaryk University
Structure of Management Information (SMIv2)
Object example:
ipInDelivers OBDECT-TYPE SYNTAX Counters ACCESS read-only STATUS current DESCRIPTION
, ,The total number of input datagrams successfully delivered to IP user-protocols (including ICMP)'' ::= { ip 9 }
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Simple Network Management Protocol (SNMP)      Management Information Base (MIB)
FACULTY
OF INFORMATICS
Masaryk University
Management Information Base (MIB)
a virtual database used for managing the entities in a communications network
■ organized in a global MIB tree
■ each MIB (module) represents a sub tree of this global MIB tree
defines the properties of managed objects within a device to be managed (a router, switch, etc.)
■ each managed device keeps a database of values for each of the definitions written in the MIB it supports
every device that supports SNMP must also support a generic MIB-2 module
■ device manufacturers are allowed to define their own device-specific MIBs
remember: the standard describing how to create a MIB SMI(v2)
temet
MIB II (RFC 1213)
device-specific MIB vendorl
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Simple Network Management Protocol (SNMP)
Management Information Base (MIB)
FACULTY
OF INFORMATICS
I   Masaryk University
Management Information Base (MIB)
MIB-2 Module and UDP group example
1.3.6.1.2.1
udpLocal udpLocal Address Port
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Simple Network Management Protocol (SNMP)
Simple Network Management Protocol (SNMP)
FACULTY
OF INFORMATICS
I   Masaryk University
Simple Network Management Protocol (SNMP)
Simple Network Management Protocol (SNMP)
■ uses both SMI and MIB to allow the network management
■ it allows:
■ a manager to retrieve the value of an object defined in an agent
■ the agent responses with the value
■ a manager to store a value in an object defined in an agent
■ the agent informs about the success/failure or responses with the newly set value
■ an agent to send an alarm message about an abnormal situation to the manager
■ SNMPv3 defines eight types of packets (PDUs):
■ GetRequest, GetNextRequest, GetButkRequest, SetRequest, Response, Trap, InformRequest, and Report
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Simple Network Management Protocol (SNMP)     Simple Network Management Protocol (SNMP)
FACULTY
OF INFORMATICS
Masaryk University
Simple Network Management Protocol (SNMP)
Communication Architecture Scheme
SNMP management station
SNMP agent
Management application
4->
w
o1 m pí
DO 0) => u< 01
Pí +J M
S3 +J
0)
P CO oj
CT1 Cl) PÍ
tu
OJ w c o
CO
a> Pí P oj O
crj S-l
SNMP manager
UDP
IP
Network-dependent protocols
Application manages objects
SNMP messages
Luděk Matýska • Network Management • Spring 202
Managed resources
SNMP managed objects
P
10. 01
o<
OJ
Pí
4-1 OJ
O
J					
i i					
p					
es	p	íse			
	ta				
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pí	o"	:Resf			
p	ID				
M tu	Pí P			E-i	
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et					
					
		_5			
SNMP agent
UDP
IP
Network-dependent protocols
59/65
Simple Network Management Protocol (SNMP)
Simple Network Management Protocol (SNMP)
FACULTY
OF INFORMATICS
Masaryk University
Simple Network Management Protocol (SNMP)
Protocol Data Units (PDUs)    Types of Packets
UDP connections
SNMP manager
Client
Luděk Matýska • Network Management • Spring 2023
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Simple Network Management Protocol (SNMP)
Simple Network Management Protocol (SNMP)
FACULTY
OF INFORMATICS
I   Masaryk University
Simple Network Management Protocol (SNMP)
Protocol Data Units'(PDUs') Format
			PDU	
				VarBind list
				-
PDU	Request	Error	Error	
type	ID	status	index	
	Variable		Value	■ ■ •	Variable		Value	
								
■ Request ID - a sequence number used by the manager in a request
and repeated by the agent in a response
■ allows to match a request and a corresponding response
■ Error Status - an integer used only in response PDUs to indicate an error reported by an agent
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Simple Network Management Protocol (SNMP)
Simple Network Management Protocol (SNMP)
FACULTY
OF INFORMATICS
Masaryk University
Simple Network Management Protocol (SNMP)
Protocol Data Units' (PDUs') Format - Codes for PDU Type field
Data	Class	Format	Number	Whole Tag (Binary)	Whole Tag (Hex)
GetRequest	10	i	00000	10100000	AO
GetNextRequest	10	i	00001	10100001	Al
Response	10	i	00010	10100010	A2
SetRequest	10	i	00011	10100011	A3
GetBulkRequest	10	i	00101	10100101	A5
InformRequest	10	i	00110	10100110	A6
Trap (SNMPv2)	10	i	00111	10100111	A7
Report	10	i	01000	10101000	A8
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Conclusion
FACULTY
OF INFORMATICS
Masaryk University
Lecture overview
Network Management by ISO
Network Elements Management Systems Management Network Management Support Organization Basic Components Refined
Structure of Management Information
Management Information Base (MIB)
Simple Network Management Protocol (SNMP)
Conclusion
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Conclusion
FACULTY
OF INFORMATICS
Masaryk University
Network Management - Recapitulation
■ Network Management by ISO - FCAPS model
■ Fault management, Configuration management, Accounting management, Performance management, Security management
■ basic network management components
■ Network Elements - contain management interfaces (provided by agents)
■ Management Network - dedicated vs. shared network
■ Network Management System - centralized, distributed, or hierarchical layout
■ Management Support Organization - non-technical aspects of network management
■ Simple Network Management Protocol (SNMP)
■ manager-agent approach
■ « a framework - involves SMI, MIB, and other components
■ objects identified by identifiers (01 Ds), each object has a type (defined by SMI)
Ludek Matyska • Network Management • Spring 2023 64/65
Conclusion
FACULTY
OF INFORMATICS
I   Masaryk University
Network Management - Literature
■ A. FarreL: Network Management: Know It ALL Morgan Kaufmann, 2009.
■ A. CLemm: Network Management Fundamentals. Cisco Press, 2006.
■ B. Forouzan: Data Communications and Networking, 4th edition. McGraw-Hill, 2007.
■ M. Subramanian: Network management: principles and practice. Addison-Wesley, 2000.
■ J. R. Burke: Network Management: Concepts And Practice, A Hands-On Approach. Pearson Education, 2008.
■ etc.
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