Business data communications 5e by stallings chapter 19

Chapter 19: Network Management Business Data Communications, 5e Fault Management • A fault is an abnormal condition that requires management attention (or action) to repair • Fault is usually indicated by failure to operate correctly or by excessive errors • Users expect quick and reliable resolution Business Data Commun ications, 5e Responding to Faults • When faults occur, it is critical to quickly: – Determine exactly where the fault is – Isolate the rest of the network from the failure so that it can continue to function without interference – Reconfigure or modify the network to minimize the effect of removing the failed component(s) – Repair or replace the failed components to restore the network to its initial state Business Data Commun ications, 5e User Requirements for Fault Management • Tolerant of occasional outages, but expect speedy resolution • Requires rapid and reliable fault detection and diagnostic management functions • Impact and duration of faults can be minimized with redundancy • Good communication with users about outages and faults is critical Business Data Commun ications, 5e Accounting Management • Reasons for accounting management: – Internal chargebacks on network use – User(s) may be abusing access privileges and burdening the network at the expense of other users – Users may be making inefficient use of the network – Network manager can plan better for network growth if user activity is known in sufficient detail • Accounting reports should be generated under network manager control • Facility must provide verification of users' authorization to access and manipulate accounting information Business Data Commun ications, 5e Configuration Management • Concerned with: – initializing a network and 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 • Operations on certain components should be able to be performed unattended • Network manager needs the capability to change the connectivity of network components • Users should be notified of configuration changes Business Data Commun ications, 5e Performance Management • Issues of concern to the network manager include: – – – – – 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? • Network managers need performance statistics to help them plan, manage, and maintain large networks Business Data Commun ications, 5e Security Management • Concerned with – – – – generating, distributing, and storing encryption keys monitoring and controlling access to networks access to all or part of the network management information collection, storage, and examination of audit records and security logs • Provides facilities for protection of network resources and user information • Network security facilities should be available for authorized users only Business Data Commun ications, 5e Network Management Systems • Collection of tools for network monitoring and control, integrated in these ways: – A single user-friendly operator interface for performing most or all network management tasks – A minimal amount of separate equipment • Consists of incremental hardware and software additions implemented among existing network components • Designed to view the entire network as a unified architecture, and provide regular feedback of status information to the network control center Business Data Commun ications, 5e Network Management System Architecture Business Data Commun ications, 5e 10 Components of the NMS • All nodes run the Network Management Entity (NME) software • Network control host or manager runs the Network Management Application (NMA) • Other nodes are considered agents Business Data Commun ications, 5e 11 Network Management Entity • Collection of software contained in each network node, devoted to the network management task • Performs the following tasks: – Collect statistics on communications and network-related activities – Store statistics locally – Respond to commands from the network control center – Send messages to NCC when local conditions undergo a significant change Business Data Commun ications, 5e 12 Simple Network Management Protocol (SNMP) • Originally developed for use as a network management tool for networks and internetworks operating TCP/IP • A collection of specifications that include the protocol itself, the definition of a database, and associated concepts • Network Management Model – – – – Management station Agent Management information base Network management protocolP Business Data Commun ications, 5e 13 SNMPv1 Configuration Business Data Commun ications, 5e 14 Role of SNMPv1 Business Data Commun ications, 5e 15 SNMPv2 • Released in 1992, revised in 1996 • Addressed functional deficiencies in SNMP • Accommodates decentralized network management • Improves efficiency of data transfer Business Data Commun ications, 5e 16 Elements of SNMPv2 • Each "player" in the network management system maintains local database of network management information (MIB) • Standard defines information structure and allowable data types (SMI) • At least one system must be responsible for network management; others act as agents • Information exchanged using simple request/respond protocol, usually running over UDP Business Data Commun ications, 5e 17 Structure of Management Information (SMI) • Defines framework within which a MIB can be defined and constructed – data types that can be stored – formal technique for defining objects and tables of objects – scheme for associating a unique identifier with each actual object in a system • Emphasis on simplicity and extensibility Business Data Commun ications, 5e 18 SNMPv2 Protocol Operation • Basic unit of exchange is the message – Outer message wrapper – Inner protocol data unit (PDU) • Common fields in PDUs – Request-id field is an integer assigned such that each outstanding request can be uniquely identified – Variable-bindings field contains a list of object identifiers; depending on the PDU, the list may also include a value for each object Business Data Commun ications, 5e 19 SNMPv2 PDU Format QuickTime™ and a TIFF (LZW) decompressor are needed to see this picture Business Data Commun ications, 5e 20 SNMPv3 • Released in 1998, addressed security deficiencies in SNMP and SNMPv2 • Does not provide a complete SNMP capability; defines an overall SNMP architecture and a set of security capabilities for use with SNMPv2 Business Data Commun ications, 5e 21 SNMPv3 Services • User-Based Security (USM) model – Authentication – Privacy • View-Based Access Control Model (VACM) – Access Control Business Data Commun ications, 5e 22 ... ications, 5e 13 SNMPv1 Configuration Business Data Commun ications, 5e 14 Role of SNMPv1 Business Data Commun ications, 5e 15 SNMPv2 • Released in 199 2, revised in 199 6 • Addressed functional deficiencies... object Business Data Commun ications, 5e 19 SNMPv2 PDU Format QuickTime™ and a TIFF (LZW) decompressor are needed to see this picture Business Data Commun ications, 5e 20 SNMPv3 • Released in 199 8,... status information to the network control center Business Data Commun ications, 5e Network Management System Architecture Business Data Commun ications, 5e 10 Components of the NMS • All nodes run