Wireless Detection and Connection Delays

Hi

What are the factors that determine the signal detection and actually get a connetion to a wireless hot-spot. What is the "acceptable" time in which an application - say a wifi signal sniffer ... should be able to detect the signal and establish a connection when in vicinity of a wireless hotspot. If anyone has done any profiling about this or have any idea about this, please help.

Thanks Sandeep

Reply to
sandeepsinghal
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The minimum connection time is the interval between SSID broadcasts. You can't connect unless you can first identify. Typical broadcasts are 10 times per second so you should be able to identify an access point in less than 100msec. However, the actually connection requires considerable back and forth traffic. This includes associations requests (6 exchanges), key exchange (6 ??? requests), DHCP requests (4 exchanges), ARP requests (2 exchanges), and initial DNS lookup. If there's some security involved (802.11x) there's even more packets going back and forth. It's difficult to calculate unless one knows the setup.

Passive sniffer (Kismet) = 1 management packet. Active sniffer (Netstumbler) = 2 packet exchanges.

This is why sniffers are more sensitive and faster at finding access points than an actual connection and login. They only need one or two packets to produce a useable data point, while a full connection and login requires many more.

I suspect that this is your homework assignment. If so, please use the resources at the skool and do your own research. If not, you did not state what you are trying to accomplish and what you have to work with. It's difficult to answer such theoretical questions without context.

Reply to
Jeff Liebermann

Thanks a lot for your response. BTW, It is not my homework assignment. I am work on a product which provides wifi connectivity taking control over windows wireless zero config. My objective was to make a comparision between windows wireless management and ours. Being new to the field, i was looking for ideas. Yours were a good ideas giving me a starting point. Let me search for more. Thanks again. Sandeep

Reply to
sandeepsinghal

My appologies, but I wasn't sure and really didn't want to ruin some students learning experience.

I would welcome such a product. There are ocassional queries in this newsgroup for replacement wireless client managers that offer more control and more diagnostics than Windoze Wireless Zero Config. Specifically, the deficiencies (in order of importance) are:

  1. An inability to select a specific access point by MAC address when the SSID's are all identical.
  2. Diagnostics that will disclose WEP/WPA/authentication errors and generate a log file showing the negotiation progress. At this time, it is impossible to use WZC for troubleshooting connection failures.
  3. Site survey tools for searching for access points that clearly identify the access point to avoid spoofed and fake access points.
  4. More detailed status and signal reports (signal strength, signal to noise ratio, error rate, connection speed, and MAC address).
  5. Lack of a traffic monitor (bits/sec in both directions).
  6. Lack of ability to adjust how agressively the client will stay connected to an access point before giving up and searching for a better signal. This is needed for roaming until 802.11r is released. Intel recently added this feature to their Proset client.
  7. WPA support for Windoze 2000.

I can run some simple timing tests for you next week. However, these are easy to do and you can probably do them yourself. You'll find that simple initial discovery and connection is almost instantaneous with anyone's client. However, when you add encryption and RADIUS authentication to the puzzle, the times will increase. Add an automatic VPN connection (SecureNet), and the connect times increase even more. If there is a software firewall installed on the client computah, add some more time.

I'm not sure why connect time is an issue. Most users have become familiar with what has become an ordeal process for using wireless. From start, it might be as bad as:

  1. View available networks.
  2. Select SSID of network.
  3. Supply WPA phrase.
  4. View splash screen. Click OK on legal disclaimer.
  5. Supply login and password.
  6. Start VPN client.
  7. Select terminating system.
  8. Supply login and password.
  9. Display and select available servers.
  10. Start user application.

Sounds to me like an ideal candidate for some scripting or login automation.

Good luck.

Reply to
Jeff Liebermann

Thanks for you comments again! Would you say I use WMI and VBscript for writing the Automation Scripts as you suggested ? Also, if you have some sample scripts that can help me or point me towards the right direction, I would really appreciate this.

Thanks again Sandeep

Reply to
sandeepsinghal

If only MS would expose the objects above to work with. WMI ought to be where these objects exist, but ...

fundamentalism, fundamentally wrong.

Reply to
Rico

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