Network Instrument’s Observer
(Version 8.3) is a $995 software-based network monitoring and protocol
analysis tool capable of evaluating 802.11 wireless LANs.
A definite advantage of using Observer is its wide
breath of analysis features for wireless LANs. As with other tools on the market,
Observer captures packets on the radio side of the network and displays the
packets for either manual or automatic analysis. Observer does a great job of
doing this, however, with the capability to identify thousands and decode over
500 packets types.
After receiving packets, Observer can filter the
packets and activate message windows, captures, logs, and external programs.
For example, you can interface Observer to send an e-mail or dial a pager with
a specific status code whenever the traffic through an access point reaches
75% capacity. This is an important feature when managing performance demanding
Observer provides extensive statistics information. As an example, you can
easily baseline the network using Observer, and then use ongoing statistics
information to trigger applicable event notices. This helps you determine when
to upgrade, which is becoming more and more important as companies begin to
push wireless LANs to the limit.
With the Observer trending functions, you can set sampling of the network to
occur as often as necessary to obtain the results you need with minimal overhead
impact on the wireless network. The results of the trend analysis help you analyze
critical historical information that can aid in supporting the system during
high stress periods.
After installing and running the software on a Windows XP laptop, my operating
system locked up. Network Instruments quickly explained that the problem was
that I needed to update the firmware in my radio card NIC, which I promptly
After completing the firmware upgrade, I didn’t have any problems with lockups.
Lesson learned: Be sure to upgrade your own firmware before trying it.
To use Observer, you’ll need any wireless network adapter that has an NDIS 3.0/3.1 (or
greater) driver that supports promiscuous mode. As examples, the cards from
the following enterprise class vendors will work: Cisco,
Nortel and Proxim.
When not in use by Observer, you can continue using the radio card for other
Observer works with both 802.11a
and 802.11b and even 802.11g wireless LANs . With the growing number of 802.11a networks in addition to the
solid base of 802.11b, the capability of supporting both types of network in
an analyzer such as Observer is a necessity. In addition to wireless protocols,
however, Observer also supports Ethernet, Token
Ring, and FDDI,
which increases the utility and value of Observer over the competition.
For 802.11a and 802.11b operation, Observer runs on Microsoft Windows 2000
and XP. There is no support for Windows CE, PalmOS, or Linux, however. As a
result, you can’t run Observer on a handheld device, which limits the utility
of the tool. Even the smaller laptops can be a bit cumbersome to carry around
for extended periods of time when performing a widespread assessment of a larger
When using Observer for the first time, expect some up-front time to learn
how to navigate through the screens and operate the various functions. The screens
could be a bit more intuitive.
All-in-all, Observer is a good 802.11 monitoring and protocol analysis tool,
assuming you’re comfortable with using it from a laptop when moving about the
facility. With Observer’s comprehensive features, though, you can tackle just
about any protocol and performance issue while supporting a wireless LAN.
Jim Geier provides independent consulting services to companies
developing and deploying wireless network solutions. He is the author of the
book, Wireless LANs and
on deploying wireless LANs.
Join Jim for discussions as he answers questions in the 802.11 Planet Forums.