Chapter 16: Network Management

1. Chapter 16:Network Management Principles of Computer Networks and Communications M. Barry Dumas and Morris Schwartz

2. Objectives • Describe the purpose and function of network management in corporate networks • Distinguish between the roles of people and technology in managing corporate network and identify various responsibilities and functions for each • Identify essential elements in network management planning • Describe considerations on what to manage and what not to manage including impact on dimensions of time, equipment, people, and money • Explain the basic structure of network management systems and specifically illustrate how SNMP operates • Demonstrate the significance of network performance monitoring and indicate the types of information that might assist in network management • Describe the ISO FCAPS network management model • Provide business considerations that should be incorporated into a network management plan • Provide an example of an open systems network management solution Principles of Computer Networks and Communications

3. Overview “From a business perspective, whether we are dealing with simple or complex networks, their management should be a centralized operation.” • For network management, corporations are concerned with managing • Main corporate networks • Isolated corporate LANs and VLANs • Connections to public data networks (PDNs) • Public data networks (PDNs) • Privately owned and operated WANs • Provide public access and charge fees for connection services • Commonly used by corporations to extend the reach of their own networks Principles of Computer Networks and Communications

4. Overview • WAN/LAN management—Who’s responsible? • Often, corporations do not own their own WANs • WANs are typically managed by WAN owners who are responsible for • Link maintenance • Upgrades • Problem fixes Problems within the corporate LAN are the province of corporate network management. Principles of Computer Networks and Communications

5. “An organization’s own internal networks routinely comprise multiple LANs interconnected by internal routers.” Overview • Routers • See multiple internal LANs as simply connections • Move transmissions among them via network layer protocols (typically using the TCP/IP suite) If TCP / IP is used, the collective internal networkis called an intranet. Principles of Computer Networks and Communications

6. Overview • Intranets • Are accessible only to authorized employees • With external connections reside behind corporate firewalls vs. • Extranets • Are accessible to people outside the company • Provide limited access to specific parts of an intranet Internal corporate network External “special clients” network access Principles of Computer Networks and Communications

7. Overview • Network management system (NMS) • Developed in the 1990s • Systems for automated network management • Offered simple method for monitoring and managing entire corporate networks NMS problems • Simplification was a myth • Not necessarily compatible with corporate devices • NMS (proprietary) monitoring devices were complicated NMS consoles in the late 1990swere more versatile and compatible Principles of Computer Networks and Communications

8. “No matter how automated a company’s network management system is, the ultimate responsibility for network management rests with people.” People and Systems • Technology tasks in network management • Databases track access rights, usage, and passwords • Sniffers monitor traffic • Hardware and software modules installed in network devices provide activity data and respond to commands • NMS consoles integrate and coordinate (all of the above) Principles of Computer Networks and Communications

9. People and Systems Who manages the networks? • Large company (complex networks) • Administrators are • Accounts managers (passwords/access rights) • Technicians (resolve faults/perform upgrades) • Upper-lever managers (oversee department-level operations) • Small company (few networks) • One (or two) network administrators (for tasks above) Principles of Computer Networks and Communications

10. Network administrator Responsibilities Network installation, management, and control (access) Network set-up, maintenance, security Software licensing and acquisition, application installation, distribution, and upgrading Performance and activity monitoring, performance testing Network design, reconfiguration Storage management, back-up, restore Systems administrator Responsibilities Firewall configuration, password assignment, management of user accounts Acquisition, installation, and maintenance of network hardware, software, and operating systems Back-up and recovery E-mail address assignment Network Management—Who are these people? Job responsibilities will be organization-dependent Job responsibilities will overlap Principles of Computer Networks and Communications

11. People and Systems • Four perspectives for network management planning and process • Scope • Heterogeneity • Size and complexity • Intermittent failures Principles of Computer Networks and Communications

12. People and Systems • Planning and process—scope issues are associated with establishing priorities; that is deciding • What network devices to manage • How closely devices should be managed • What network devices not to manage The more closely a device is managed,the more it costs! (time, people, equipment, money) Principles of Computer Networks and Communications

13. People and Systems • Planning and process scope—setting priorities First priority • Critical systems—those that are most important to the functioning of the business Next priority • Systems whose malfunctioning is disruptive but not disabling to the business Last priority • Systems where faults cause little to no disruption e.g., bank transaction processing e.g., online ordering e.g., employee desktop login Principles of Computer Networks and Communications

14. People and Systems • Planning and process—heterogeneity • Network hardware and software are most likely heterogeneous—products of different manufacturers even for the same type of device • Hardware and software might • Be based on different standards • Have the same standard but different versions • Have proprietary standards • Be installed by employees apart from what is “authorized” Principles of Computer Networks and Communications

15. People and Systems • Network manager responsibilities in a heterogeneous network (with examples) • Helping determine network design • Presenting the case for reducing variety to an acceptable minimum as systems are replaced and upgraded • Managing existing systems • What to manage? How closely? • Discovery and enforcement • Removing unauthorized products and preventing their installation Managing a heterogeneous network compounds as the network grows! Principles of Computer Networks and Communications

16. People and Systems • Planning and process—size and complexity • The larger and more interconnected the networks, the more difficult they are to manage • Network managers need to keep networks trim and fit • Avoid unneeded connections • Block unused ports (to reduce intrusion risk) • Consider segmenting LANs as traffic patterns emerge • Balance connectivity needs with options for providing for those needs (e.g., more cable or go wireless) Principles of Computer Networks and Communications

17. People and Systems • Planning and process—intermittent failures • Discovering sources and causes of intermittent failures is one of the more frustrating and time-consuming situations for network managers and affected parties • Intermittent failures might appear as • Random packet loss • Odd instances of dropped connections • Arbitrary login rejections • NMSs might help to isolate problems (e.g., logging alarms and notifications) Intermittent failures are often orders of magnitude more difficult than even catastrophic failures Principles of Computer Networks and Communications

18. Structuring Network Management • There are two major incompatible protocol sets for structuring and managing networks • Simple network management protocol (SNMP) • Developed by the Internet Engineering Task Force (IETF) • TCP/IP layer 5 protocol • Latest version is SNMPv3 • Common management information protocol (CMIP) • OSI layer 7 protocol SNMP is a simpler protocol than CMIP SNMP is muchmore popular than CMIPso the next slides will not be discussing CMIP Principles of Computer Networks and Communications

19. Structuring Network Management “The degree to which a network or intranet can be managed depends upon which of its components are managed devices.” • Network managed device characteristics • Has network management modules (NMMs) installed • NMMs provide software agents that monitor their devices, collecting information about their device states and packets they process • Network managed devices (examples) • Computers (workstations) • Hubs • Switches • Routers SNMP provides a structure for information exchange between the managed devices and the manager. Principles of Computer Networks and Communications

20. Structuring Network Management • SNMP collects information (“objects”) • Collections of objects—management information base (MIB) • Objects (aka MIB objects or managed objects) • Individual items of information within each type (generic or device-specific) are called objects • Objects are contained in MIB modules • Device manufacturers provide MIB modules for their devices • Objects are defined by manufacturers according to the needs/capabilities of their devices • Types of information collected • Generic data—commonly defined for any device following the TCP/IP protocol (e.g., device IP address) • Device-specific data—particular to the device itself (e.g., a configuration setting) The MIB modules incorporated in a managed device determine what it can report and how it can be controlled. Principles of Computer Networks and Communications

21. Structuring Network Management • SNMP network management in operation • A network management module (NMM) agent sends data to SNMP manager software for any of the following • When polled • At intervals • When a problem arises • When a problem is impending • An NMS can perform most routine operations automatically Principles of Computer Networks and Communications

22. Structuring Network Management Example:MIB object: failchkthat counts frames failing their frame check • SNMP—network management communications • Manager-initiated communications follow a “fetch/store” (also “get/set”) object-oriented model comprising two types of commands • Fetch (read data from devices) • Retrieves data collected by device agents • Store (write data to devices) • Acts to control the device by resetting counters or re-initializing the device • Each MIB object has a unique name that the manager uses when sending a fetch or store command Manager Sends fetch failchkcommand to read status Sends store failchkcommand to reset device Principles of Computer Networks and Communications

23. Structuring Network Management • SNMP—network management communications • Device problem • When some fault (failure) occurs or is about to occur, the device sends an alarm (fault alert message) to the manager • Alarm types are predefined in the MIB Principles of Computer Networks and Communications

24. Structuring Network Management • SNMP—network management setup • Basic • Manager can request agent information only from devices that are on the same network as the manager • Remote • For devices on other attached networks • Requires remote monitoring (RMON) protocol Principles of Computer Networks and Communications

25. Structuring Network Management • SNMP—network management setup • Remote • For devices on other attached networks • Requires remote monitoring (RMON) protocol • Extension of SNMP • Defines statistics that can be passed between managers and remote devices • Defines functions that can be activated for control purposes RMON uses probes to collect/analyze data—For traffic monitoring—To send alarms about impending or actual faults Principles of Computer Networks and Communications

26. Structuring Network Management Everyone has SNMPMIBs Agents send data to SNMP manager software when polled ? To extendednetworks D Fig. 16.1Managed network structure Principles of Computer Networks and Communications

27. Concerns of Network Management • Network management—concerns • More than discovering, locating, and resolving faults • Faults can be • Actual failures • Symptoms of unusual activity that can • Eventually become a failure • Cause failures in other parts of an intranet This points to the importance of monitoring network performance. Correction is usually simpler if a problem can be identified before that (failure) state is reached. Principles of Computer Networks and Communications

28. Concerns of Network Management With automatic network managing systems, do we still need people? • Yes! • Reacting to alarms and taking action for those that cannot be handled automatically • Reviewing NMS tracking statistics to spot potential problem areas • Taking proactive steps to ward off impending failure Principles of Computer Networks and Communications

29. “A commonly used model for network management is ISO’s FCAPS.” FCAPS FCAPS • Fault management • Discovering, locating, correcting, and logging failures and conditions likely to lead to failures • Configuration management • Device software and software components • Network physical and logical topologies and protocols • Accounting management • Efficient allocation of resources (e.g., user accounts, password management) • Performance management • Track performance measures and keep networks running efficiently • Security management • Controlling access to network resources (i.e., network itself and data contained) Principles of Computer Networks and Communications

30. Network Performance Measures • Throughput • Number of bits per second (bps) at the destination node • Resource utilization • Percentage of a resource’s capacity used by packets it is processing • Error rate (also bit error rate) • Number of erroneous bits received as a proportion of the total number of bits sent • Latency • Time between packet transmission and receipt (measure of network responsiveness) • Mean time before failure (MTBF) • Average length of time before a network component fails • Mean time to repair (MTTR) • Length of time between when a failure occurs (or is reported) and when the device is put back into service Principles of Computer Networks and Communications

31. Business Considerations “Business decisions regarding internal resources and systems usually are made on a cost/benefit basis.” • Network management is an expensive proposition! • Costs can include • Hardware and software • (Highly salaried) support personnel • Costs from downtime Principles of Computer Networks and Communications

32. Business Considerations • Businesses tend to go in one of two directions (views) • Network management as a cost center • Budget as little as possible to get by • Leads to large unexpected expenses from problems • Network management as the most important information system component • Leads to overinvestment in complex NMSs, large inventories of spare equipment, and very large staffs The solution is to apply a business casethat incorporates a network management function onlyif it directly addresses a business problem. Principles of Computer Networks and Communications

33. Open Network Management • Freeware • Available without charge (or with non-mandatory requests for donations) • Owned and distributed by its creator • Not subject to modification by others vs. • Open source • Available without charge • Not owned by anyone (i.e., in the public domain) • Available for viewing and modification by others • OpenNetwork Management System (OpenNMS) Billed as “the world’s first enterprise grade network management platform developed under the open source model.” Principles of Computer Networks and Communications