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.
CNS NetFlow Collector Engine: Cisco hardware that gathers every flow in a net-
work segment.
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.
Third-party tools: Such as Sniffer, AirMagnet Wifi Analyzer, BVS Yellowjacket
802.11, NetIQ Vivinet Assessor, Netcordia NetMRI, and SolarWinds Orion.
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.
No WAN links are saturated (no more than 70 percent sustained network utilization).
The response time is generally less than 100ms (one-tenth of a second); more com-
monly, less than 2ms in a LAN.
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.
No segments have more than one cyclic redundancy check (CRC) error per million
bytes of data.
On the Ethernet segments, less than 0.1 percent of the packets result in collisions.
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.
The number of output queue drops has not exceeded 100 in an hour on any Cisco
router.
The number of input queue drops has not exceeded 50 in an hour on any Cisco router.
The number of buffer misses has not exceeded 25 in an hour on any Cisco router.
The number of ignored packets has not exceeded 10 in an hour on any interface on a
Cisco router.
 
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