TD 92685EN
28 June 2012 / Ver. A
Troubleshooting Guide
Ascom i62 VoWiFi Handset
71
Appendix D: External
Appendix D: External Troubleshooting Tools
A support engineer of LAN and WLAN installations should be equipped with a software
toolbox containing additional troubleshooting tools commonly used in the trade. The
toolbox should preferably contain tools for both the Wired and Wireless LAN.
Tools are available from many sources like:
• WLAN and LAN infrastructure vendors.
If you work often with a specific WLAN vendor it can be beneficia
l to learn the tools that
are produced by that vendor. Some tools may be free while others are costly.
• Niche commercial software publishers.
Commercial software products are often highly pri
ced but a license will give you support,
and there are often training programs available to attend.
• Free or low cost tools that can be downloaded from
the Internet.
Note: The tools
that may be used are, in general, a matter of the support engineer’s
personal preference. However when the support of the Ascom TAC team has been requested
in resolving an issue, they may request information, in the form of a trace or dump, from a
specific tool.
The tools can be divided in groups as follows:
• VoIP tools
-Software IP-PBX and Software clients
- Performance measurem
ent tools
•WLAN tools
- RF tools such as spectrum analyzers, heat m
apper tools and site survey tools
•Protocol Tools
Wireless supported Protocol Analyzer (Sniffer)
•Report Tools.
D.1 Protocol Analyzer Tools
Capturing the traffic data with a wireless or wired protocol analyzer can be very useful when
troubleshooting a system. Specifically when using WLAN, capturing traffic in the spot where
the problems arise may provide valuable information about the traffic that is not
transferred over to the wired network, for example, retransmissions, rates, etcetera. Since
the wired side is almost always a switched network capturing traffic is not trivial since
access to the switches is needed to create a spanned port to get the data mirrored out to
the sniffer. On the other hand, capturing the WLAN which is a broadcasted medium is very
convenient. The only equipment needed is a laptop, for physical mobility, and a wireless
network card that the sniffer software supports.
General Practices
• Always try to capture as much data as possible. If filt
ering options exists try to filter the
result after the capture is saved. Applying a filter to the capture itself may exclude
interesting packets and ultimately render the capture useless.
• When capturing wireless bear in mind that the capture devi
ce has the same limitations
as other wireless devices, that is, it will miss packets, be subjected to disturbances and
can be out of range. To ensure the best possible wireless capture try to place the capture
device in between the monitored devices, that is, between the handset and the AP. Do
not place
the capture device too close to another wireless device and keep at least 0.5 m
between the capture device and monitored devices. If placed too close, traffic may be
overheard on the wrong channels, for example packets on channel 6 will appear on
channel 11, or not heard at all due to saturated receivers.
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