Chapter 16: Network Management Principles of Computer Networks and Communications M. Barry Dumas and...
-
Upload
alannah-whitehead -
Category
Documents
-
view
217 -
download
0
Transcript of Chapter 16: Network Management Principles of Computer Networks and Communications M. Barry Dumas and...
Chapter 16:Network Management
Principles of Computer Principles of Computer Networks and CommunicationsNetworks and Communications
M. Barry Dumas and Morris SchwartzM. Barry Dumas and Morris Schwartz
Principles of Computer Networks and Communications
2Chapter 16
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
3Chapter 16
Overview
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
“From a business perspective, whether we are dealing with simple or complex networks, their
management should be a centralized operation.”
Principles of Computer Networks and Communications
4Chapter 16
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
5Chapter 16
Overview
Routers See multiple internal LANs as simply connections Move transmissions among them via network layer
protocols (typically using the TCP/IP suite)
“An organization’s own internal networks routinely comprise multiple LANs
interconnected by internal routers.”
If TCP / IP is used, the collective internal networkis called an intranet.
Principles of Computer Networks and Communications
6Chapter 16
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
7Chapter 16
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
8Chapter 16
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)
“No matter how automated a company’s network management system is, the ultimate responsibility for network
management rests with people.”
Principles of Computer Networks and Communications
9Chapter 16
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
10Chapter 16
Network Management—Who are these people?Network administratorResponsibilities 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 administratorResponsibilities 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
Job responsibilities will overlap
Job responsibilities will be organization-dependent
Principles of Computer Networks and Communications
11Chapter 16
People and Systems
Four perspectives for network management planning and process Scope Heterogeneity Size and complexity Intermittent failures
Principles of Computer Networks and Communications
12Chapter 16
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
13Chapter 16
People and Systems
Planning and process scope—setting prioritiesFirst 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
14Chapter 16
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
15Chapter 16
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
16Chapter 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
17Chapter 16
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
18Chapter 16
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 much more popular than CMIPso the next slides will not be discussing CMIP
Principles of Computer Networks and Communications
19Chapter 16
Structuring Network Management
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
“The degree to which a network or intranet can be managed depends upon which of its
components are managed devices.”
SNMP provides a structure for information exchange between the managed devices
and the manager.
Principles of Computer Networks and Communications
20Chapter 16
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
21Chapter 16
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
1. When polled2. At intervals3. When a problem arises4. When a problem is impending
An NMS can perform most routine operations automatically
Principles of Computer Networks and Communications
22Chapter 16
Structuring Network Management
SNMP—network management communications
Manager-initiated communications follow a “fetch/store” (also “get/set”) object-oriented model
comprising two types of commands 1. Fetch (read data from devices)
Retrieves data collected by device agents
2. 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
Example:MIB object: failchkthat counts frames failing their frame check
Manager Sends fetch failchk command to read status
Sends store failchk command to reset device
Principles of Computer Networks and Communications
23Chapter 16
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
24Chapter 16
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
25Chapter 16
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
26Chapter 16
Structuring Network Management
Fig. 16.1Managed network structure
Everyone has SNMP MIBs
Agents send data to SNMP manager software when polled?
D
To extendednetworks
Principles of Computer Networks and Communications
27Chapter 16
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
Correction is usually simpler if a problem can be identified before that (failure) state is reached.
This points to the importance of monitoring network performance.
Principles of Computer Networks and Communications
28Chapter 16
Concerns of Network Management
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
With automatic network managing systems,
do we still need people?
Principles of Computer Networks and Communications
29Chapter 16
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)
FCAPS
“A commonly used model for network management is ISO’s FCAPS.”
Principles of Computer Networks and Communications
30Chapter 16
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
31Chapter 16
Business Considerations
Network management is an expensive proposition!
Costs can include Hardware and software (Highly salaried) support personnel Costs from downtime
“Business decisions regarding internal resources and systems usually are made on a cost/benefit basis.”
Principles of Computer Networks and Communications
32Chapter 16
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 case that incorporates a network management function only
if it directly addresses a business problem.
Principles of Computer Networks and Communications
33Chapter 16
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
Open Network Management System (OpenNMS)
Billed as “the world’s first enterprise grade network management platform developed under the open source model.”