Information Technology Reference
In-Depth Information
Network Analysis Tools
To o b t a i n a p p l i c a t i o n - l e v e l i n fo r m a t i o n , t h e I P p a c k e t n e e d s t o b e f u r t h e r i n s p e c t e d . C i s c o
devices or dedicated hardware or software analyzers capture packets or use Simple Net-
work Management Protocol (SNMP) to gather specific information. Network analysis
tools include the following:
Netformx DesignXpert Enterprise:
An integrated desktop tool for discovery,
design, configuration, quoting and proposing integrated communications network
solutions.
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CNS NetFlow Collector Engine:
Cisco hardware that gathers every flow in a net-
work segment.
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Cisco Embedded Resource Manager (ERM):
Allows for granular monitoring on a
task basis within the Cisco IOS software. It monitors the internal system resource uti-
lization for specific resources, such as the buffer, memory, and CPU.
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Third-party tools:
Such as Sniffer, AirMagnet Wifi Analyzer, BVS Yellowjacket
802.11, NetIQ Vivinet Assessor, Netcordia NetMRI, and SolarWinds Orion.
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Network Checklist
The following network checklist can be used to determine a network's health status:
New segments should use switched and not use dated hub/shared technology.
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No WAN links are saturated (no more than 70 percent sustained network utilization).
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The response time is generally less than 100ms (one-tenth of a second); more com-
monly, less than 2ms in a LAN.
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No segments have more than 20 percent broadcasts or multicast traffic. Broadcasts
are sent to all hosts in a network and should be limited. Multicast traffic is sent to a
group of hosts but should also be controlled and limited to only those hosts regis-
tered to receive it.
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No segments have more than one cyclic redundancy check (CRC) error per million
bytes of data.
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On the Ethernet segments, less than 0.1 percent of the packets result in collisions.
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A CPU utilization at or more than 75 percent for a 5-minute interval likely suggests net-
work problems. Normal CPU utilization should be much lower during normal periods.
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The number of output queue drops has not exceeded 100 in an hour on any Cisco
router.
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The number of input queue drops has not exceeded 50 in an hour on any Cisco router.
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The number of buffer misses has not exceeded 25 in an hour on any Cisco router.
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The number of ignored packets has not exceeded 10 in an hour on any interface on a
Cisco router.
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