FACULTY OF INFORMATICS Masaryk University PA160: Net-Centric Computing II. Network Management Luděk Matýska Slides by: TomasRebok Spring 2022 Luděk Matýska • Network Management • Spring 2022 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 Luděk Matýska • Network Management • Spring 2022 2/65 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) Luděk Matýska • Network Management • Spring 2022 Motivation FACULTY OF INFORMATICS Masaryk University 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 Luděk Matýska • Network Management • Spring 2022 4/65 Motivation FACULTY OF INFORMATICS Masaryk University 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 2022 ^ 'I ---'BÖH >hü—ESI WWW Sen Corp Network Motivation FACULTY OF INFORMATICS I Masaryk University 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 "pings" 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) Luděk Matýska • Network Management • Spring 2022 6/65 Motivation FACULTY OF INFORMATICS I Masaryk University 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. Luděk Matýska • Network Management • Spring 2022 7/65 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) Luděk Matýska • Network Management • Spring 2022 8/65 Network Management FACULTY OF INFORMATICS I Masaryk University 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. Luděk Matýska • Network Management • Spring 2022 9/65 Network Management Network Management by ISO FACULTY OF INFORMATICS 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 ■ Reconfiguration ■Documentation — Reactive — Proactive Performance management —Throughput Luděk Matýska • Network Management • Spring 4p_2^esponsetjme — Capacity — Traffic Security management Accounting management 10/65 Network Management Network Management by ISO FACULTY OF INFORMATICS Masaryk University 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.) Luděk Matýska • Network Management • Spring 2022 11/65 Network Management Network Management by ISO FACULTY OF INFORMATICS I Masaryk University 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) Luděk Matýska • Network Management • Spring 2022 12/65 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) Luděk Matýska • Network Management • Spring 2022 13/65 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 Ludék Matyska • Network Management • Spring 2022 14/65 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 Luděk Matýska • Network Management • Spring 2022 15/65 Basic Network Management Components FACULTY OF INFORMATICS 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) Luděk Matýska • Network Management • Spring 2022 16/65 Basic Network Management Components FACULTY OF INFORMATICS Masaryk University 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 Luděk Matýska • Network Management • Spring 2022 17/65 Basic Network Management Components Network Elements FACULTY OF INFORMATICS Masaryk University 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 Requests Responses+ Events Managed Agent System $ ("server) Luděk Matýska • Network Management • Spring 2022 18/65 Basic Network Management Components Network Elements FACULTY OF INFORMATICS Masaryk University 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. Ludek Matyska • Network Management • Spring 2022 19 / 65 Basic Network Management Components Network Elements FACULTY OF INFORMATICS I Masaryk University 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 Luděk Matýska • Network Management • Spring 2022 20/65 Basic Network Management Components Network Elements FACULTY OF INFORMATICS Masaryk University Network Elements (NEs) II. Management Agents Managing System "Manager" Managed System "Agent" 1 manages Management Interface Embedded J Management i Intelligence Core Agent Logic Management Agent MIB interacts with represents Real Resource (device, operating system...) Figure: Anatomy of a Management Agent. Luděk Matýska • Network Management • Spring 2022 21/65 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 Friedrich "Hund" Managed System Real Resource Luděk Matýska • Network Management • Spring 2022 22/65 Basic Network Management Components Management Systems FACULTY OF INFORMATICS I 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. hierarchical vs. 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 Ludek Matyska • Network Management • Spring 2022 23 / 65 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 2022 24/65 Basic Network Management Components Management Systems FACULTY OF INFORMATICS Masaryk University (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) 25/65 Basic Network Management Components Management Systems FACULTY OF INFORMATICS Masaryk University (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 Luděk Matýska • Network Management • Spring 2022 26/65 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 2022 27/65 Basic Network Management Components Management Network FACULTY OF INFORMATICS I Masaryk University 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 Luděk Matýska • Network Management • Spring 2022 28/65 Basic Network Management Components Management Network FACULTY OF INFORMATICS Masaryk University Management Network Dedicated vs. Shared management and production networks I Production Traffic Management Traffic Production v-Network (a) Shared Network for Management and Production Traffic X Dedicated Management Network / / II 1 / 1 gh, Uta, m * í \ §m. Um, / Production Network ^—^ 1' f (b) Dedicated Management Network Luděk Matýska • Network Management • Spring 2022 29/65 Basic Network Management Components Management Network FACULTY OF INFORMATICS Masaryk University 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 Luděk Matýska • Network Management • Spring 2022 30/65 Basic Network Management Components Management Network FACULTY OF INFORMATICS I Masaryk University 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" Luděk Matýska • Network Management • Spring 2022 31/65 Basic Network Management Components Management Support Organization FACULTY OF INFORMATICS Masaryk University 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: ■ well-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 Luděk Matýska • Network Management • Spring 2022 32/65 Basic Network Management Components Management Support Organization FACULTY OF INFORMATICS I Masaryk University 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. Luděk Matýska • Network Management • Spring 2022 33/65 Basic Network Management Components Basic Components Refined FACULTY OF INFORMATICS Masaryk University Basic Components of Network Management Refined Management Support „Ji ií M tli/Li Organization WIM Management Technology Management Systems (User Proxies) Management Protocols "Rules of Conversation" Management Agents (Real-World Proxies) —r Real World Production Network Management Network User Concern Network Devices Figure: Basic Parts of the Network Management - Refined. Ludek Matyska • Network Management • Spring 2022 34/65 Simple Network Management Protocol (SNMP) FACULTY 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) Luděk Matýska • Network Management • Spring 2022 35/65 Simple Network Management Protocol (SNMP) FACULTY OF INFORMATICS I Masaryk University 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 Luděk Matýska • Network Management • Spring 2022 36/65 Simple Network Management Protocol (SNMP) FACULTY OF INFORMATICS Masaryk University 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 ■ a pp Li cation-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 Luděk Matýska • Network Management • Spring 2022 37/65 Simple Network Management Protocol (SNMP) FACULTY OF INFORMATICS Masaryk University 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 Ludék Matyska • Network Management • Spring 2022 38 / 65 Simple Network Management Protocol (SNMP) FACULTY OF INFORMATICS Masaryk University Simple Network Management Protocol (SNMP) III. ■ uses the Manager-Agent approach ■ 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 Luděk Matýska • Network Management • Spring 2022 39/65 Simple Network Management Protocol (SNMP) FACULTY OF INFORMATICS I Masaryk University Simple Network Management Protocol (SNMP) Components Management SNMP 1 SMI MIß J ■ 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 Luděk Matýska • Network Management • Spring 2022 40/65 Simple Network Management Protocol (SNMP) FACULTY OF INFORMATICS Masaryk University 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 Luděk Matýska • Network Management • Spring 2022 41/65 Simple Network Management Protocol (SNMP) FACULTY OF INFORMATICS Masaryk University 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? ,h--------------1 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.......... Encapsulate the request in a GetRequest message Luděk Matýska • Network Management • Spring 202í| 42/65 Simple Network Management Protocol (SNMP) Structure of Management Information FACULTY OF INFORMATICS I Masaryk University 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 Luděk Matýska • Network Management • Spring 2022 43/65 Simple Network Management Protocol (SNMP) Structure of Management Information FACULTY OF INFORMATICS I Masaryk University 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 44/65 Simple Network Management Protocol (SNMP) Structure of Management Information FACULTY OF INFORMATICS Masaryk University 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., 13.6.1.2.1 ■ this representation is used by SNMP ■ or using a sequence of textual names separated by dots ■ e.g., iso.org.dod.internetmgmtmib-2 this representation is used by people Luděk Matýska • Network Management • Spring 2022 Simple Network Management Protocol (SNMP) Structure of Management Information FACULTY OF INFORMATICS Masaryk University 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 of operators ■ 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 Luděk Matýska • Network Management • Spring 2022 46/65 Simple Network Management Protocol (SNMP) Structure of Management Information FACULTY OF INFORMATICS Masaryk University Structure of Management Information (SMIv2) Object type - Simple data types Type Size Description INTEGER 4 bytes T l n i 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 2 - 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 Luděk Matýska • Network Management • Spring 2022 47/65 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 (simple variables) d. Sequence of (sequences) Luděk Matýska • Network Management • Spring 2022 48/65 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 Format Number 2 bits 1 bit 5 bits Luděk Matýska • Network Management • Spring 2022 49/65 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 Luděk Matýska • Network Management • Spring 2022 50/65 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 2022 51/65 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). Luděk Matýska • Network Management • Spring 2022 52/65 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 Length Value (14) (integer) (4 bytes) ■ OCTET STRING with a value "HI" 04 02 48 49 00000100 00000010 01001000 01001001 Tag Length Value Value (String) (2 bytes) (H) (1) Luděk Matýska • Network Management • Spring 2022 53/65 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) p-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 - Luděk Matýska • Network Management • Spring 2022 54/65 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 } Luděk Matýska • Network Management • Spring 2022 55/65 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 Luděk Matýska • Network Management • Spring 2022 56/65 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 1 2345678 11 12 udpLocal udpLocal Address Port Luděk Matýska • Network Management • Spring 2022 57/65 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 Luděk Matýska • Network Management • Spring 2022 58/65 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-" a oj P cr oj ■i-1 oj W ai en oj Pi +J X! OJ !s ■M oj O co QJ Pi OJ 00 oj w fl o a. w oj Pi OJ a 03 n Eh 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 SNMP manager Client UDP connections GetRequest GetNextRequest GetBulkFtequest SetRequest Response Trap Inform Request Report To another manager To another manager Luděk Matýska • Network Management • Spring 2022 60/65 Simple Network Management Protocol (SNMP) Simple Network Management Protocol (SNMP) FACULTY OF INFORMATICS Masaryk University Simple Network Management Protocol (SNMP) Protocol Data Units'(PDUs') Format PDU VarBind list PDU type Request ID Error status Error index 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 Luděk Matýska • Network Management • Spring 2022 61/65 Simple Network Management Protocol (SNMP) Simple Network Management Protocol (SNMP) FACULTY OF INFORMATICS Masaryk University Simple Network Management Protocol (SNMP) Protocol Data Units' (PDUs') 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 Luděk Matýska • Network Management • Spring 2022 62/65 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 Luděk Matýska • Network Management • Spring 2022 63/65 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 2022 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. Luděk Matýska • Network Management • Spring 2022 65/65