Network Instruments GigaStor User Manual page 25

Ultimately, where to deploy probes depends on the design of your particular network and where you require
visibility. A probe only shows your analyzer the data that is visible to that probe. An Ethernet Probe's visibility,
for example, is limited to what a particular switch's SPAN/mirror port can deliver. A specialized hardware probe
connected through a TAP sees only the traffic traversing that link. If 100% coverage is important to you, install
TAPs on all the high-speed critical links in or near the core of your network, and probes plugged into the SPAN/
mirror ports of switches on the edge.
For example, placing TAPs on the full-duplex links that connect servers or server farms to core switches will give
you complete visibility into all traffic between servers and their clients. Connecting additional half-duplex probe
appliances to SPAN/mirror ports at the edge of the network will let you focus in on any segment or station on
the network for detailed problem resolution.
Failure to deploy the right probes in the right place can result in "blind spots" on your network, and an
incomplete picture can lead to inefficient troubleshooting and expensive mistakes.
Some of the main things a probe can be used for include:
monitor server, link, and application performance
tweak or troubleshoot trunk performance
troubleshoot workstation connections
Figure 6 (page 25) shows your options and what you gain or lose by placing probes at certain locations.
to open a this diagram as its own PDF.
Figure 6: Probe placement options
Deciding where to place probes in your network | 25
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