Network Instruments Observer - Manual (Page 23)

Switched Observer
© 2002 Network Instruments, LLC 17
Switched Observer
Switches provide both performance advantages and debugging headaches for
network administrators.
The advantages are obvious: since a switch enables the network to handle
traffic effectively, in a way transparent to devices on the network and the
people using them, it provides efficiency and functionality from a centralized
location. Substituting virtual port connections for hard-wired port
connections enables multiple simultaneous connections between stations. It
also permits more efficient use of bandwidth by managing heavily trafficked
connections without the necessity of any intervention (or awareness, for that
matter) on the part of the user on either end.
The disadvantages should also be obvious: since the entire purpose of a
switch is to handle traffic in a way transparent to the rest of the network, it's
difficult to monitor the performance of a switch. This is not a problem when
the network is consistently performing optimally—if it is not broken, or
breaking, there’s no need to fix it—but when a problem does arise, the very
nature and function of a switch makes it difficult to detect, diagnose, and treat
the problem, as a switch is intended to hide what it is doing from the rest of
the network. Because of these complexities, it’s necessary to reconfigure
Observer’s Probe to monitor a switch.
When monitoring a switch, many of Observer’s modes/tools remain
available, but some act differently in order to help the network administrator
monitor the functionality of a switch.
Those modes that become unavailable will be grayed out.