Transcript Net Mgmt ch7.2

Network Management Mechanisms
Network Management Mechanisms
•Two major network management protocols:
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Simple Network Management Protocol (SNMP)
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Common Management Information Protocol (CMIP).
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CMIP includes CMIP over TCPIP (CMOT).
•Management protocols provide mechanism for
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retrieving, changing, and transport of network management
data across the network.
•SNMP: forms the basis for many network management systems.
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Provides facilities for collecting and configuring parameters
from network devices:
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get (to collect the value of a parameter)
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get-next (to collect the value of the next parameter in
the list)
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set (to change the value of a parameter).
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Provides events notification:
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trap is a user-configurable threshold for a parameter
Network Management Mechanisms
Network Management Mechanisms
•SNMP parameters:
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Management Information Bases (MIBs)
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Based on a type of network device, technology, or protocol|
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SNMPv3 provides
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more secure authentication
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ability to retrieve blocks of parameters
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and trap generation for most parameters
•Common Management Information Protocol CMIP/CMOT:
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Allows for more types of operations.
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CMIP/CMOT features:
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globally unique object naming
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object classification
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alarm reporting
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audit trails
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test management
•SNMP is simpler to configure and use than CMIP/CMOT
Monitoring Mechanisms
Monitoring Mechanisms
•Obtaining values for end-to-end, per-link, and per-element characteristics.
•The monitoring process involves:
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collecting data about the desired characteristics
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processing data
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displaying processed data
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archiving a subset of this data.
•Data collection and processing, through polling:
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ensure that the data are current and valid
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data may or may not reflect the characteristics we wish to monitor
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values may be derived from the gathered data
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other values may be modified (e.g., added, subtracted, time-averaged)
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This is processing of the data.
Monitoring Mechanisms
Monitoring Mechanisms
•Sets of raw processed and unprocessed data will need to be displayed:
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standard monitor displays,
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field-of-view
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wide-screen displays
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and special-purpose displays. Along with
•Techniques to display data:
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logs and textual displays
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graphs and charts (both static and moving)
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alarms
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by symbols (e.g. showing parts of the network as a cloud)
Monitoring Mechanisms
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Saving data:
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saved permanent or temporary
primary storage
 network management server (short period of time)
 secondary storage (archives)
 aggregation of data from multiple primary storage sites
 storage server for the network
 tertiary storage (archives), (the most permanent, slowest)
 all devices may combined on a single device.
Monitoring Mechanisms
Monitoring Mechanisms
Monitoring Mechanisms
Monitoring for Event Notification
•An event is something that occurs in the network that is noteworthy. Could be:
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Problem
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Failure
•Events may be noted in:
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Log file
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Display
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Alarming
•Events are short-lived changes in the behavior of the network
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Real-time analysis : setting thresholds or boundaries for short-term or
immediate notification of events
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Example: Ping is used to gather roundtrip delay information, which is
presented as a chart on the monitoring system.
Monitoring Mechanisms
Monitoring for Event Notification
•
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A threshold of 100 ms
Reaches 100ms alarming to notify the network manager that a
problem may exist in the network.
•Real-time analysis:
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Requires short polling intervals
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There is a trade-off between the number of characteristics and
network devices polled for real-time analysis versus the amount
of resources (capacity, CPU, memory, storage) needed to support
such analysis.
Monitoring Mechanisms
Monitoring for Event Notification
•Amount of network data generated by the periodic polling of multiple
characteristics can impact the overall performance of the network.
•For example:
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a network with 100 network devices/elements (NE)
each element has 4 interfaces
each interface is monitored for 8 characteristics
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(100 NE)∗(4 Interfaces)∗(8 char.) = 3200 char.
Monitoring Mechanisms
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If each of the 3200 characteristics generates 8 bytes of data and an estimated 60
bytes of overhead
 amount of data generated per polling:
 (3200 char)∗(suppose polling interval = 5 seconds
 1.74 Mb of traffic would be spread out over the 5 seconds, or 384
Kb/second.
For a period of one day
 amount of traffic (1.75 Mb)∗(720 polling intervals/hour)∗(24 hours/day) =
30.2 GB
 amount of data stored (3200 characteristics/polling interval)∗(8 bytes)∗(720
polling intervals/day)∗(24 hours/day) = 442 MB data stored per day
Over one year = 161 GB of data 8 +60 Bytes) = 2176 KB of traffic, or 1.74 Mb of
traffic
Monitoring Mechanisms
Monitoring for Trend Analysis and Planning
•Trend analysis utilizes network management data to determine longterm network behaviors or trends.
•This is helpful in planning for future network growth.
•In doing continuous, uninterrupted data collection, usually with long
polling intervals (minutes or hours instead of seconds),
•Polls for each characteristic are saved to network management on a
regular basis, and over a long period of time
Monitoring Mechanisms
Monitoring Mechanisms
Instrumentation Mechanisms
•Instrumentation: the set of tools and utilities needed to monitor and
probe the network for management data.
•Mechanisms: include access to network management data via SNMP,
monitoring tools, and direct access.
•Instrumentation can be coupled with monitoring, display, processing.
and storage to form a complete management system.
Monitoring Mechanisms
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SNMP (currently in version 3) provides:
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access to management information base (MIB) variables, including those in MIBII, other standard MIBs (e.g., DS1 MIB), enterprise-specific MIBs, and other
monitoring MIBs (remote monitoring (RMON), and switch monitoring (SMON).
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Monitoring tools include utilities such as:
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ping, Traceroute, and TCPdump,
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while direct-access mechanisms include:
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telnet, FTP, TFTP, and connections via a console port.
Monitoring Mechanisms
Configuration Mechanisms
•Configuration is setting parameters in a network device for operation and control.
•Configuration mechanisms include:
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direct and remote access to devices and downloading configuration files
(Figure 7.7):
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SNMP set commands
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Telnet and command line interface (CLI) access
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Access via HTTP
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Access via common object request broker architecture (CORBA)
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Use of FTP/TFTP to download configuration files
Monitoring Mechanisms