Losing Wireless Connectivity
Last Post: October 17, 2005:
Iam part of the IT team in an educational setup, where each user is given access to certain files on the file servers.My main problem is that we are experiencing issues of lost connectivity.This generally happens a few minutes after the students have logged on, resulting in lost teaching time.We as an institute provide the students with a bank of 30 Dell Latitude 505 and Dell Inspiron 510 series laptops with 1.4 GHz ,Intel Pro 2200 B/G wireless cards,although the students are welcome to bring their own notebooks.On analysing we have found out that this issue is not hardware specific but location specific as in ,wireless connectivity lost on the first floor of the building. I need you guys to guide me as to how to solve this problem. We are using Cisco AP 1200s . I need to know how to check the performances of the APs on the first floor and guidelines to any utilities that can monitor the performance of the network. Additionally I would like to know how to best alter the existing network with minimal change to best suit our needs.In case any other clarification is needed pls ask , I could explain it in greater detail.It should be noted that the APs are connected in the corridor with classrooms on either side.i have also checked the sessions on the WLSE but without much feedback to get to any conclusion.Please try and help me as this issue is just blowing out of proportion with the management.
I'm sure you have thought of this, but what is the user to AP ratio? In high density/traffic environments, a loss of connectivity can happen even with good equipment like Cisco. That's the first thing that came to mind anyway. Let us know!
Thanx GT Hill for your reply.Well we have thought of the same but please let me know if we can find out the performance of the APs via a software or utility.Currently the APs have benn configured to not allow more than 25 sessions each.Also a thing to emntion is that we have just recently upgraded the cards to B/G instead of only B. But whats confusing is that this problem is faced on only one corridor of the institute mostly.Please try and provide a solution for this query.Thanks again
This is the time for another site survey to analyze your condition. It may have not been properly done or there are additional obstacles added that are degrading your signal. I would hope the later part.
What type of construction are the APs blasting the signal through into the class rooms? What are the APs output power? Sounds like a bunch of multipath taking place and perhaps some noise being generated. File cabinets in the area?
You must take into account the losses through the construction especially concrete walls,. The construction and output power of the APs are really things you what to consider.
Also see what type of RF cabling is used in the system and any splitters as they induce losses. Make sure they are matched to rate your Wireless 2.4 GHz range.
Use a Cisco 350 AP card and test the RF connectivity.
if you don't have Cisco Card:
Use Netstumbler to test for RSSI levels make sure they are above no less than -75 dBm to the back side of the roomswhere the users are located.
Also the density of APs as mentioned is a factor that warrants your results of the test.
Cisco APs supports logging to a syslog server.
Configure a Unix server to log the messages from the APs, and configure the APs to send logs to that server. Those messages can give you some info.