Introduction to Network Management

Transcription

1 Introduction to Network Management Chu-Sing Yang Department of Electrical Engineering National Cheng Kung University

2 Outline Introduction Network Management Requirement SNMP family OSI management function areas Network management system Network management software architecture Distributed network management Proxies

3 Outline Introduction Network Management Requirement SNMP family OSI management function areas Network management system Network management software architecture Distributed network management Proxies

4 The Case for Management Typical problem Remote user arrives at regional office and experiences slow or no response from corporate web server Where do you 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 Corp Network Remote User WWW Servers

5 The Case for Management Remote User With proper management tools and procedures in place, you may already have the answer Consider some possibilities 1. What configuration changes were made overnight? 2. Have you received a device fault notification indicating the issue? 3. Have you detected a security breach? 4. Has your performance baseline predicted this behavior on an increasingly congested network link? Regional Offices Corp Network WWW Servers

6 Solving Problem Procedure An accurate database of your network s topology, configuration, and performance A solid understanding of the protocols and models used in communication between your management server and the managed devices Methods and tools that allow you to interpret and act upon gathered information Predictability Response Times High Availability Security

7 Introduction Network Management System (NMS) Automatic versus human effort Increased network size Increased complexity Heterogeneous equipment Equipment from multiple vendors

8 Outline Introduction Network Management Requirement SNMP family OSI management function areas Network management system Network management software architecture Distributed network management Proxies

9 Network Management Requirements Ease of use Security features Restoral capability Ability to delete/add Ability to monitor network availability Traffic rerouting Improved automation User registration Improved reporting Ability to monitor response time

10 Network Management Requirements Control corporate strategic assets Control complexity Improve service Balance various needs Reduce downtime Control cost

11 Outline Introduction Network Management Requirement SNMP family OSI management function areas Network management system Network management software architecture Distributed network management Proxies

12 Introduction to SNMP Simple Network Management Protocol Provides a tool for multi-vender, interoperable network management used across a broad spectrum of product types include end systems, bridges, switches, routers and telecommunications equipment TCP/IP based

13 Simple Network Management Protocol A set of standards for network management a protocol a data base structure specification a set of data objects

14 SNMP Family SNMPv1 Proposed in 1989 SNMPv2 Proposed in 1993 Revised in 1995 An upgrade to SNMPv1 Add functional enhancements to SNMP and codify the use of SNMP on OSI-based networks

15 SNMP Family (cont.) SNMPv3 Issued in 1998 Define a security capability for SNMP and an architecture for future enhancements Used with the functionality provided by SNMPv2 or SNMPv1

16 RMON Remote network MONitoring a supplement to SNMP extend the capabilities of SNMP to include management of LANs as well as the devices attached to those networks RMON 1 issued in 1991 RMON 2 issued in 1995

17 Outline Introduction Network Management Requirement SNMP family OSI management function areas Network management system Network management software architecture Distributed network management Proxies

18 OSI Management Functional Areas Fault management Configuration management Accounting management Performance management Security management

19 Fault Management The facilities that enable the detection, isolation, and correction of abnormal operation of the OSI environment What is a fault? an abnormal condition that requires management attention (or action) to repair indicated by failure to operate correctly or by excessive errors Communication line is cut A crimp in the cable Certain errors may occur occasionally and are not normally considered to be faults

20 Fault Management When a fault occurs Determine exactly where the fault is Isolate the rest of the network from the failure Reconfigure or modify the network to minimize the impact of operation Repair or replace the failed components

21 User requirements for Fault Management Fast and reliable problem resolution Receive notification and correct the problem immediately Requires rapid and reliable fault detection and diagnostic management Provides fault tolerance Redundant components and alternate communication routes Fault management capability itself should be redundant Keep informed of the network status Reassurance of correct network operation through mechanisms that use tests or analyze dumps, logs, alerts, or statistics Problem tracking and control Ensure the problem is truly resolved and no new problems are introduced Fault management should have minimal effect on network performance

22 Configuration Management Configuration management is concerned with Initializing a network Gracefully shutting down part or all of the network Maintaining, adding, and updating the relationships among components and the status of components themselves during network operation

23 Requirements for Configuration Management The network manager needs the capability to Identify initially the components that comprise the network Define and change the connectivity of components Define and modify default attributes, and load the predefined sets of attributes into the specified network components Reconfigure a network for performance evaluation, network upgrade, fault recovery or security checks End users want to inquire about the upcoming status of resources and their attributes before reconfiguration Generate configuration reports Periodic basis Response for a request Only authorized end users can manage and control network operation (software distribution and updating)

24 Accounting Management The facilities that enable charges to be established for the use of managed objects costs to be identified for the use of those managed objects

25 Accounting Management Network managers track the use of network resources by end user or end-user class An end user or group of end users may be abusing its access privileges and burdening the network at the expense of other users End users may be making inefficient use of the network, and network manager can assist in changing procedures to improve performance The network manager is easier to plan for network growth if end user activity is known in sufficient detail

26 Requirements for Accounting Management The network manager can specify the kinds of accounting information to be recorded at various nodes the desired interval between sending the recorded information to higher-level management nodes the algorithms to be used in calculating the charging Generate accounting reports Provide the capability to verify end users authorization to access and manipulate the information

27 Performance Management The facilities needed to evaluate the behavior of managed objects the effectiveness of communication activities Functions of performance management Monitoring Tracks activities on the network Controlling Enables performance management to make adjustments to improve network performance

28 Issues of Performance Management What is the level of capacity utilization? Is there excessive traffic? Has throughput been reduced to unacceptable levels? Are there bottlenecks? Is response time increasing?

29 To deal the issues of PM The network manager focus on some initial set of resources to be monitored in order to assess performance levels Appropriate metrics and values with relevant network resources as indicators of different levels of performance The count of retransmission on a transport connection Monitor many resources to provide information in determining network operating level Collect and analyze information, and then using the resultant analysis as feedback to the prescribed set of values

30 User Requirements for Performance Management End users want to know the average and worst case response times the reliability of network services Performance statistics can help managers Plan, manage and maintain large networks Recognize potential bottlenecks in advance balance or redistribute traffic load by changing routing tables

31 Security Management The facilities that address those aspects of OSI security essential to Operate OSI network management correctly Protect managed objects network resources end user information End users want to know the proper security policies are in force and effective the management of security facilities is itself secure

32 Issues of Security Management Managing information protection, and access control facilities Generating, distributing and storing encryption keys Passwords, authorization or access control information must be maintained and distributed Monitoring and controlling access to computer networks and to all or part of the network management information SM involves with the collection, storage, and examination of audit records and security logs the enabling and disabling of these logging facilities

33 Outline Introduction Network Management Requirement SNMP family OSI management function areas Network management system Network management software architecture Distributed network management Proxies

34 Network Management Systems (NMS) NMS is a collection of tools for network monitoring and control Designed to view the entire network as a unified architecture addresses and labels assigned to each point specific attributes of each element and link known to the system Single operator interface with a powerful but user-friendly set of commands a minimal amount of separate equipment (hardware/software) is necessary NMS software resides in the host computers and communications processors (bridges, routers)

35 Network Management Systems The active elements of the network provide regular feedback of status information to the network control center NMS for single vendor equipment versus for multiple-vendor network Two or more network control centers are used for high availability (backup) one center is idle or collecting statistics the other center is used for control

36 Network Management System Network control Host (manager) NMA NME Appi Comm OS Server (agent) NME Appi Comm OS Workstation (agent) NME Appi Comm OS Router (agent) NME Comm OS NMA = network management application NME = network management entity Appl = application Comm = communications software OS = Operating system

37 Network Management Configuration Network Management Element (NME) Contains a collection of software devoted to the NM task in each network node collects statistics Stores statistics locally Responds to commands from network control center (manager) Transmit collect statistics to manager Change a parameters (a timer in a transport protocol) Provide status information Generate artificial traffic for testing Send messages to network control center for significant changes in local conditions be referred to as an agent Agents are implemented in end systems and nodes

38 Network Management Configuration Network Management Application (NMA) include an operator interface to allow an authorized user to manage the network Respond to user commands display information issue commands to NMEs through the network Communicate with and control NME in other nodes Application-level network management protocol

39 Outline Introduction Network Management Requirement SNMP family OSI management function areas Network management system Network management software architecture Distributed network management Proxies

40 Network Management Software Architecture Three categories User presentation software Network management software Communications and database support software

41 Architectural model of NMS Unified user Interface Presentation of network management Information to users Network Management application... Network Management application Application element Application element... Application element Network management data transport service MIB access module Communications protocol stack Management information base Managed networks

42 User Presentation Software An interface in manager systems monitor and control the network An interface in agent systems network testing and debugging view or set parameters locally Presentation tools to organize, summarize, and simplify the information as much as possible to avoid information overload graphical presentations user interface should be the same at any node, regardless of vender

43 Network Management Software Three-layer architecture Network management application layer Application element layer Network management data transport service layer

44 Network Management Software (Cont ) Network management application Provides services of interest to users FCAPS Each application covers a broad area of network management and should exhibit consistency over various types of configurations (LAN, WAN,..) Application elements Implement primitive and general-purpose network management functions generating alarms or summarizing data Implement basic tools used by one or more network management applications Developed based on software reuse

45 Network Management Data Transport Service The module consists of a NM protocol used to exchange management information among managers and agents a service interface to the application elements Provides very primitive functions (get, set and trap)

46 Communication & Database Support Software Network management software needs access to a local MIB, and to remote agents and managers Local MIB at an agent contains Information reflecting the configuration and behavior of this node Parameters used to control the operation of this node Local MIB at a manager contains node-specific information summary information about agents under control

47 Communication & Database Support Software MIB access module Include basic file management software that enables access to the MIB Convert local MIB format to a standardized form across the NMS Communications protocol stack OSI or TCP/IP stack Support the network management protocol Support communications among agents and managers

48 Outline Introduction Network Management Requirement SNMP family OSI management function areas Network management system Network management software architecture Distributed network management Proxies

49 Distributed Network Management A centralized NMS enables the manager to maintain control over the entire configuration, balancing resource against needs and optimizing the overall utilization of resources Why distributed network management? the proliferation of low-cost, high power PCs & workstations the proliferation of departmental LANs local control and optimization of distributed applications distributed computing Architecture of distributed network management hierarchical architecture department-level managers manage downsized applications and PC LANs

50 Benefits Distributed Network Management network management traffic overhead is minimized Offers greater scalability eliminates single-point failure Elements for hierarchical architecture distributed management workstations be given limited access for monitoring and control manage the departmental resources one central workstation (with a backup) global access rights to manage all network resources interact with less-enabled management stations

51 Distributed Network Management Distributed management system architecture management clients Provide the user access to management services and information Provide a graphical user interface may access one or more management servers management servers are the heart of the system support a set of management applications and a MIB store common management data models route management information to applications and clients managed network devices Are managed directly by one or more management servers through a vendor-specific element manager or proxy

52 Typical distributed management system architecture Management clients ( PCs, workstations ) Network Management server Management application MIB Management server Management application MIB Network Element manager Element manager Network resources ( servers, routers, hosts ) with management agents

53 Outline Introduction Network Management Requirement SNMP family OSI management function areas Network management system Network management software architecture Distributed network management Proxies

54 Proxies Why proxies? older systems may not support network management standards small systems are not suitable to be implemented fullblown NME some components do not support agent software Modems and multiplexers Operations of proxies translate requests and responses among managers and the target system act on behalf of one or more other nodes

55 Proxy manager architecture Management application Proxy manager Management application Client Server Client proxy Client stub stub stub stub Protocol Protocol Protocol Protocol stack stack stack stack Standard operations and event reports Proprietary operations and event reports