Troubleshooting and FAQs
- Some access points or wireless routers may rate-limit the handling of ICMP packets as a matter of policy or process them at a lower priority. If your hardware falls in this category then it may be necessary to temporarily disable that feature while using NetSurveyor-Pro.
- We've chosen 23.8 Mbps as the default value for the real-world maximum throughput. This affects how percentages are reported in the Statistical Grid and Adapter Heatmap / Waterfall chart. The default value of 23.8 Mbps was chosen since that represents 44% of the theoretical maximum of an 802.11 g wireless network (i.e. 54 Mbps) -- the most common protocol currently deployed. If you would like to change the default value to better accommodate slower (i.e. 802.11 b) or faster (i.e. 802.11 n) wireless networks then this default value can be changed by selecting Options / Adjust Optimal Rate... from the main menu. A dialog box will appear and you can then select a real-world maximum throughput that better reflects the wireless networks currently being tested or monitored. The value 44% was extrapolated from the following references:http://repository.cs.aueb.gr/getdoc.php?papercode=CPWR-18-2006 and http://www.atheros.com/pt/whitepapers/Methodology_Testing_WLAN_Chariot.pdf
- When testing multiple adapters with different access points and wireless routers and using static IP addresses for the adapters then care must be taken to ensure that not only are the adapter and Gateway IP addresses on the same subnet but, also, the Gateway IP address assigned to the adapter truly matches that of the access point or wireless router it associates with. If this is not the case, then ICMP messaging will fail and you will see the number of connection breaks continue to increment in the Adapter Connection Breaks chart. In other words, for ICMP messaging to work then two conditions must hold: (a) the adapter and Gateway IP addresses must exist on the same subnet; and (b) the Gateway IP address assigned to the adapter must truly match the IP address of the access point or wireless router the adapter is associated with. If you find it necessary to temporarily change the Gateway IP address that NetSurveyor-Pro uses to send ICMP messages then select Options / Gateway IP Addresses... from the main menu. A dialog box will appear that allows you to edit the Gateway IP address for a particular adapter. Please note that this does not change the Gateway IP address in Windows -- this only affects the destination IP address that NetSurveyor-Pro uses to send ICMP messages.
- If you are testing multiple adapters concurrently then this note may be of interest. Because most access points or wireless routers come pre-configured with 192.168.1.1 as their IP address, then it would not be uncommon to have multiple adapters sending ICMP messages to the same Gateway IP address. So, a problem arises when an application wishes to send a message to a Gateway IP address that is shared by multiple NICS -- which adapter is used to send the message? Because NetSurveyor-Pro needs to test each adapter separately then it is essential that it have control over which adapter is used to send messages. To achieve this, as NetSurveyor-Pro repeatedly measures the throughput of each adapter then Windows' routing table is temporarily modified to ensure that messages are sent to the Gateway IP address via the correct adapter. Turns out that on Windows Vista SP1 there is a more elegant way of controlling which adapter is used to send ICMP messages than manipulating routing tables -- and when NetSurveyor-Pro is running on Vista SP1 then it does use this alternate method. So -- the point of this note is that if you are running Vista then we suggest you take the time to upgrade to Vista SP1 (if you haven't already done so).
Copyright © 2009, Nuts About Nets, LLC